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JFS
02-02-2004, 02:20 PM
I have searched his and other forums and have come up with this list:

- Long idling
- Driving too lightly/slowly
- City driving (stop & go)
- Lugging the engine (driving between 1K-2K RPMs)
- Excessively rich combustion mix (too much fuel being sprayed prior to ignition)

Any other potential causes?

TIA.

Kaz
02-02-2004, 03:02 PM
I think the last one is partly what occurs during the first four conditions. Also, 'lazy' engine use doesn't allow it to get as hot, and thus doesn't get a chance to burn up any buildup (see the RX8 spark plug thread from last week). This is why 'Italian Tune-Ups' exist.

Here's something ironic: Lazy driving often will let you get away with running a lower octane gas, because the internals don't get hot enough to create hotspots that could cause pre-ignition. But long periods of this could cause enough buildup on the piston tops to increase compression ratio that then requires higher octane fuel to prevent knocking.

Chris90
02-02-2004, 03:06 PM
What is the symptom of carbon buildup?
My mother's Integra LS 5 speed seems really unhappy to be redlined, I wonder if it's cause she never revs it past 4000 rpms? Her Hondas also develop knocking on recommended octane after 5-6 years too.

HW
02-02-2004, 04:45 PM
gotta floor the b!tch once in a while! :D

Will_325i
02-02-2004, 04:47 PM
...

- Driving too lightly/slowly

...
Ha, I'll never have this problem. :)

doeboy
02-02-2004, 05:48 PM
What is the symptom of carbon buildup?
My mother's Integra LS 5 speed seems really unhappy to be redlined, I wonder if it's cause she never revs it past 4000 rpms? Her Hondas also develop knocking on recommended octane after 5-6 years too.

Describe "unhappy". Does it knock? Does it sound all crazy or something? :dunno:
What kind of gas does she use? Could have something to do with both gas and driving habits... :dunno:

F1Crazy
02-02-2004, 06:36 PM
Carbon build up on intake valves and intake plenums is very often due to fuel composition and poor detergents used in gasoline. It is a known fact that most of commercially available gasoline doesn't have enough detergents to keep the intake valves clean. Some states are better than the others. Folks in CA that complain so often how they get screwed with lower octane gas I'm sure will be happy to know that their gas keeps their engines cleaner.

BMW did some extensive studies on the subject and their IVD test is used as one of the industry standard tests in evaluating fuel's ability to control intake valve deposits.

Pinecone
02-03-2004, 12:22 AM
I think the last one is partly what occurs during the first four conditions. Also, 'lazy' engine use doesn't allow it to get as hot, and thus doesn't get a chance to burn up any buildup (see the RX8 spark plug thread from last week). This is why 'Italian Tune-Ups' exist.

Here's something ironic: Lazy driving often will let you get away with running a lower octane gas, because the internals don't get hot enough to create hotspots that could cause pre-ignition. But long periods of this could cause enough buildup on the piston tops to increase compression ratio that then requires higher octane fuel to prevent knocking.

Octane has NOTHING to do with pre-ignition problems. Pre-ignition is caused by hot spots, like you say. But higher octane doesn't prevent pre-ignition, only the prevention of hot spots. In fact, a low use driver, who allows carbon build up is MORE likely to have hot spots (carbon bits that continue to glow past the exhaust cycle into the compression cycle).

A lower performance driver CAN use lower octane fuel because of the lower demands on power, leading to lower cylinder pressures, which is the driving force on octane requirements.

Octane is the ability of a fuel to resist detonation, which is NOT the same thing as pre-ignition. Detonation is AFTER ignition by the spark plug.

Actually what we used to think of as carbon build up inside the combustion chamber is mor likely to have been caused by lead in the old days. Lead requires a certain heat level to be fully scavenged from the combustion chamber, and especially from the spark plug electrodes. When the lead built up on teh spark plugs, misfiring occured. A hard run elevated cylinder temps to the point where the lead was scaveneged off the spark plugs and removed through the exhaust.

The current problme tends to be intake valve deposits. Due to teh way fuel injection work, at times the fuel is being sprayed onto the back of the closed intake valves. Since they are hot (other side is the combustion process) the fuel boils on the valve leaving deposits.

Modern fuels have detergents to remove these deposits as they form. Unformtunately these detergents also leave some deposits. So the best thing is to either use add in detergents every so often, or switch gasoline suppliers every so often.

According to one petroleum engineer, it takes about 1500 miles of driving with a single fuel to remove all the deposits left by the prior fuel. At that point, the new deposits begin to slowly form. He switches brands every 5000 miles. This allows minimal deposits to form, which are removed at the fuel switch. Using 5K miles helps him easily remember to switch.

SteveMD
02-03-2004, 08:57 AM
I also own a Volvo 850. On the volvospeed forum, the moderator, a volvo dealer mechanic, recounts how sometimes cars come in that wont run or barely run. After checking the obvious, he then takes the swedish brick out on the highway and holds a gear sufficient for 5 to 6 k rpm for 5 minutes max. End of problem. I seem to recall some mention this action gets the valves to rotate. I guess that would give the intake full exposure to incoming fuel, removing deposits at that rpm and heat range.

Artslinger
02-06-2004, 07:48 AM
According to one petroleum engineer, it takes about 1500 miles of driving with a single fuel to remove all the deposits left by the prior fuel. At that point, the new deposits begin to slowly form. He switches brands every 5000 miles. This allows minimal deposits to form, which are removed at the fuel switch. Using 5K miles helps him easily remember to switch.

Good tip, thanks.

Motown328
02-07-2004, 02:07 PM
But what if you use different gas at almost every fill-up? I don't stick to one particular brand. Wouldn't that be better than every 5k miles? :dunno:

I asked the BMW tech and he said that Bimmers don't need exhaust flushes such as STP, etc. that you add to the fuel tank to blow out deposits, the premium fuel does that by itself. What do you guys think?

Sloppynwet1
02-08-2004, 12:54 AM
Guys, lets be honest. All gasolines contain effective detergent additives. While the EPA has required all gasolines marketed in the United States to contain detergents since 1995, gasolines contain more than the minimum dosages required to provide additional protection against fuel system deposits. Premium grade gasoline contains even more detergent additive as increased insurance against fuel injector and intake valve deposit formations. But this will not eliminate the carbon build up. Remember gas is made from oil. Essential oil molecules are made up primarily of carbon, hydrogen, and oxygen. The less oxygen present, the more likely the chance of deposits. I.E-Reason for oxygenated fuels! Carbon collects. With age and driving habits, caron will collect. The flow rate and temperature has alot to do with how carbon deposits. As for leaded gas, LEAD, or rather the lack of lead in gasoline is the cause for larger amounts of Carbon Build up. Lead in our fuel helped eliminate the majority of the problems. Among other things, lead is a lubricant; a lubricant that would lubricate upper engine parts. Each time a cylinder fires - a high temperature explosion takes place burning all of the petroleum lubricants from the cylinder walls and exhaust valves. Without lead, friction and wear are increased. Lead also retards the combustion of gasoline, allowing higher engine compression and greater fuel efficiency. The lead helps control spark knock pinging and engine run on. Our new unleaded fuels have been unable to address these problems. In addition, the new unleaded fuels and current engine designs contribute to excessive carbon build up in today's engines. Carbon build up in an engine causes numerous and many times serious and costly problems. As carbon builds up on the top of pistons, it becomes red hot and pre-ignites the fuel. This preignition causes spark knock and pinging. The hot carbon on cylinder tops can also cause the engine to continue to run after the engine is turned off. Carbon build up in the intake manifold and on valves can cause a lean running condition of the engine causing poor engine operation. Left unchecked, this carbon build up can restrict fuel injectors and reduce engine performance and fuel efficiency. In older engines that require leaded gasoline, there is yet another problem. The lead in fuels also protected the valve and valve seat surfaces from transferring metal. This burning of the metal surfaces causes valve seating or sealing problems. It sounds like lead in gasoline is the miracle cure for most fuel related problems. Frankly, it is nearly that; but it also causes unacceptable exhaust emissions, emissions that are unacceptable to the environment. The best way to clean carbon build-up out of your engine is NOT to take the car out and run it as hard as you can. This only results in meetings with local law enforcement personnel, and doesn't do much for cleaning out carbon.
If you really want to clean the carbon out of your engine follow these simple steps. Fill an empty soda bottle with water. Remove your air cleaner. Start your engine. While using one hand to control the throttle, trickle the water into the carb or throttle body with the other while holding your thumb over the bottle opening. Keep the engine rpm's up so that the engine doesn't die. Make sure that you don't pour the water in too fast! Water doesn't compress and if you pour too much water in, severe engine damage can result! White smoke from the exhaust is normal. If you have a fuel injected car, you obviously won't be able to use this method, but I have had success with connecting a vacuum hose to the base of the throttle body and sticking the other end of the hose into the bottle of water. The vacuum of the engine will suck the water in, creating the same effect. This will clean out even the most stubborn carbon, by 'steam cleaning' your cylinders. Just use a small size hose. Moderation is the key!

Pinecone
02-08-2004, 06:05 AM
Wow, how many things can be wrong in a single post?

Yes, detergents are required in gasloine, but that doesn't mean that even more than the minium required is enough. Some gasolines have more detergents than others. Mobil Super Premium for one. Also different brands of gasoline s use different detergents, some of which are more effective than others, ie Chevron Techron. ANd the advice I was quoting came from a petroluem engineer working for one of the big oil companies, about applying his knowledge to his personal car, a Corvette. HE says that each additive package actually makes its own form of deposits, rather than cleaning ALL deposits.

BTW the reson for running ofr a while then switching versus switching every tank, is that with every tank, you are now running a mixture of additive packages, that are both cleaning and adding deposits. And you are now in the realm of a petroleum test driver. :)

BMW DOES recoomend occasional use of gasoline additives over an above what is in teh gas. The even sel a BMW Fuel System additive/cleaner. In the Z3 world a LOT of people have had fule tank level snsors whack out with using premium gasoline by time itself over time. Occasionaly use of either BMW or Chevron fuel system addtive removes the deposit is from the fuel level sensor that causes the trouble.

Oxygenated fuels are NOT for reducing carbon. Oxygenated fuels came into being as an interim method to fool carbuerated cars into running leaning. The carb delivers the same amount of fuel, but since part of the fuel is oxygenate, you actually end up with a lean burn. With most of the cars now being fuel injection, oxygenates are not required, but the oil companies like them, since they reduce gas mileage (less burnable fuel) and increase the sale of gasoline. It is true that leaner burning reduces carbon by having more complete combustion.

Lead is only a lubricant for the valves, and saying lubricant is a misnomer. The lead actually acted as a cushion to the closing valves. This prevented damage to the soft valve seats used at the time. All later cars (built after about 1975) have hardened valve seats that do not rely on the lead to cushion the valves. The lead was not in there for the purose of cushioning, but since it was inthere to prevent detonation, it made the manufacturers able to use a lower cost valve seat.

Lead did NOT lubricate the cylinder wall. Also cureent gasline additives along with better metallurgy have reduced the wear problems, that lead didn't even address. Think about it, it is not uncommon for a car to go 1500,000 - 200,000 miles today without havinghte engine rebuilt. in the old dddays of leaed gasoline, an engine that made it to 100,000 miles was considered a miracle. And the level of degradation that caused an engine to be rebuilt was lack of compression due to worn rings and cylinders, along with erodded valve seats (using soft materials and relying on the lead to handle shock loads).

Lead does NOT retard the combustion of gasoline. It reduces the tendancy to detonation, which is the saame as saying it increases the octane rating. Detonation is caused by a physical change to certain fuel molecules due tothe heat and pressure of combustion. They actually get reformed into compression ignitable compounds. Higher octane means teh fuel is more resistant to this occuring. Lead reduces this tendancy in gasoline molecules. Octane had NOTHING to do with burn rate.

Lead doesn't stop spark knock pinging directly. Lead increse octane, which allows more spark advance before detonation. The same thing with any form of incease in octane.

Unleaded fuels do not cause excessive carbon buildup. Excessive carbon buildup is vcaused by excessive fuel, aka a rich mixture. It can also be casued by excessively lean mixtures which are so lean they don't fully combust. This was the problem with late 70s - early 80s carbureted engines. Trying to make a carb run very lean, meant lots of the time it was running too lean. In the past, with carburetors and no concern of fuel economy, rich mixtures were used for more power, and rich mixtures allw high compression ratio for a given octane of fuel.

Carbon build up DOES cause preignition, which is NOT the same as detonation.

Fuel injected engiens don't run on. They can't. Run on is caused by carbon buildup bombined with a carb. Carbs deliver a fuel air mixture as long as air is being drawn through them. And with an engine driven fuel pump, as long as the engine was turning, fuel was delivered. The hot spots of carbon buildup allowed marginal ignition, so the engine kept turning and fuel and air ws delivered, so run on. This became a big problem in teh late 70s - early 80s due to the attempts to make carbs run lean for emissions. A fuel injection system shuts off the fuel when you shut off the ignition. No fuel, no run on. Also since the electric fuel pump also shuts off, there is no possiblity of fuel being delivered allowing run on.

The reason for the removal of lead from gasoline was th ecomng of the catalytic convertor. Cats are poisoned by lead adn stop working. The lead in gasoline was removed to allow cats to be used. That was why the cars of the 70s came in two versions, leaded gas cars, adn unleaded only gas cars. Yes, lead was finally removed from ALL road going fuels due to the problems with lead emissions, but that came almsot 10 years after the adoption of unleaded fuels due to cats. BTW aviation gasoline still uses lead.

NOdbody said to run the car well in excess of legal speeds, just do full throttle runs to redline in thoe gers that allow you remain reasonably legal. That DOES clean out deposits.

The one fully correct thing is using a VERY small stream of water to clean out carbon. The only thing is, modern engines running fuel injection and unleaded fuels don't have much carbon buildup. Heads I have pulled off of modern engines are pretty much free of carbon buildup, unlike the carbureted cars of the late 60s and 70s that I pulled heads on. So even this is not necessary.

ANd BTW, there are things called PARAGRAPHS that make your longer posts easier to read.

xspeedy
02-08-2004, 07:28 AM
Just one thing. I heard that the notion of premium fuel offering better detergent packages was wrong. In fact, the range of gasolines have the exact same package with octane as the only variable.

Perhaps some specific brand offers better or higher quantities of detergent in the premium fuel, but I'm not sure that it is the case with every product. It seems to be a marketing gimmick to get people that don't otherwise require high octane fuel to pay the extra money and line the coffers of the oil industry.

Sloppynwet1
02-08-2004, 10:34 AM
Boy, talk about wrong info in a post! You had better go back to read chemical compositions! Lead does all that and more. Yes, I must admit, metalurgy has come a long way, in which engine life has been extended. But the reason engines are running longer is due to emission requirements. In order to achieve these emission requirements, manufacturers had only one option, to improve design and structure of the engine. EX-Most of the enigines running 100-200,000 miles are the same basic design they were back in the 70's. Say Dodge 318 which was just retired. But what was employed was the use of better materilas to prolong engine life. Why did they do this, they were forced to. Either by competition, Japanese, or by regulations and emissions. During the 70's, Japanese engines were out performing american cars using leaded gas. They could exceed 100,000 where american engines would be a rare occasion. Lead cannot single out one compnent in the vehicle. IE-Vavle seats. Lead effects the whole chemical nature of the gasoline itself. It effects everything it touches. As well, many more enigines in the 70's had carbon build up due to the lack of computer engine regulation on fuel mixtures. Todays automobiles employ sensors that in fact reduce carbon build up buy reguylating the right air to fuel mixture. So, to try to make a comparrison between vehicles of today, and back then is impossible. Lead does have a function. It does act as a lubricant. It wasnt a great lubricant, but it helped. As for unleaded fuels causing excessive carbon build up, I never said that. It can build up, if your car is not tuned correctly (mixture) and driving patterns also cause build up! As well, I was placing a point at not jumping on the highway and gunning it to remove the deposit. Yes, reving the engine can help remove carbon, but it does not remove it totally. The best option is water injection.

Sloppynwet1
02-08-2004, 10:37 AM
As for premium fuels, yes some manufacturres do employ better and cleaner fuels when running premium. I must appologize at the generalization that all manufacturers do this. So have a minimum requirement to adhere to, and that is all they do.

Sloppynwet1
02-08-2004, 10:38 AM
Sorry about the paragraphs, I get running sometimes and I dont stop! LOL :yikes:

Pinecone
02-08-2004, 02:15 PM
Just one thing. I heard that the notion of premium fuel offering better detergent packages was wrong. In fact, the range of gasolines have the exact same package with octane as the only variable.

Perhaps some specific brand offers better or higher quantities of detergent in the premium fuel, but I'm not sure that it is the case with every product. It seems to be a marketing gimmick to get people that don't otherwise require high octane fuel to pay the extra money and line the coffers of the oil industry.

Several people I know i teh petroleum industry say that premium fuels have better additive packages.

I can only assuem that they know what they are talking about. :)

Pinecone
02-08-2004, 02:40 PM
Boy, talk about wrong info in a post! You had better go back to read chemical compositions! Lead does all that and more. Yes, I must admit, metalurgy has come a long way, in which engine life has been extended. But the reason engines are running longer is due to emission requirements. In order to achieve these emission requirements, manufacturers had only one option, to improve design and structure of the engine. EX-Most of the enigines running 100-200,000 miles are the same basic design they were back in the 70's. Say Dodge 318 which was just retired. But what was employed was the use of better materilas to prolong engine life. Why did they do this, they were forced to. Either by competition, Japanese, or by regulations and emissions. During the 70's, Japanese engines were out performing american cars using leaded gas. They could exceed 100,000 where american engines would be a rare occasion. Lead cannot single out one compnent in the vehicle. IE-Vavle seats. Lead effects the whole chemical nature of the gasoline itself. It effects everything it touches. As well, many more enigines in the 70's had carbon build up due to the lack of computer engine regulation on fuel mixtures. Todays automobiles employ sensors that in fact reduce carbon build up buy reguylating the right air to fuel mixture. So, to try to make a comparrison between vehicles of today, and back then is impossible. Lead does have a function. It does act as a lubricant. It wasnt a great lubricant, but it helped. As for unleaded fuels causing excessive carbon build up, I never said that. It can build up, if your car is not tuned correctly (mixture) and driving patterns also cause build up! As well, I was placing a point at not jumping on the highway and gunning it to remove the deposit. Yes, reving the engine can help remove carbon, but it does not remove it totally. The best option is water injection.

Lead is NOT used as a lubricant in fuels. Lead CAUSES more problems than it helped. Lead fouls plugs, lead causes sticking valves. The lead in the cylinder during combustion (where you say it lubricates thecylinder walls) is in a gaseous state distrubuted throughout the combustion volume, not enough to lubricate anything. Lead parcipitated out on the valve seats because they ware cool relative to the combution, AND they are protected from diret exposure to combustion flame front which would vaporize teh lead.

Lead IS used in bearing materials to allow them to embed wear particles.

Lead does not change the whole chmeical makeup of gasoline. It works in a specifc manner during combustion (a chemical reaction). Before and after combustion, it does nothing to the gasoline.

My background includes both autos for many years and aviation, as well as chemistry and engineering. Most low horesepower aircraft engines were designed for 80/87 octane aviation fuel. But it is not readily available, so you have to run them on 100LL (Low Lead), but 100LL has 4 time sthe lead of 80/87, and you get all kinds of problems from this, including fouled plugs, sticking valves.

Valve seats were changed indirectly due to emissions. Due to the removal of lead, the manufacturers had to change the valve seats or run the risk of valves failing in very short order. As a side benefits the hardened valve seats last a LOT longer without the lead, than the soft ones did with the help of lead. There have been some other changes in materials, but not great strides in materials. Rings are more typically chromed or moly filled, but they existed in the early 70s. I know, I installed them in some of my cars.

What has really helped is a better understanding of how to prep an engine. In the old days, you just bored and honed the block, hoping for some sort of pattern. Now the cross hatch patterns are carefully controlled, the block is stressed so the bores are more cylindrical while assembled. Some new block materials present a harder surface to the ring wear. That all helps.

And you state that you cannot compare the engines of today with the engines of yesterday, but you also clai that all the problems are caused by the lack of lead. But if the engines are so different, how can YOU single out the lack of led as the only reason for these problems.

And no, Japanese engines of the 70s did not regularly last over 100K miles. German engines did. And my 76 Corolla SR-5 running a 1600 cc hemi engine burned up the valves at about 100K, and it was designed to run on leaded gas. But no carbon build up when I tore it down, and it was running carburetors.

Yes, the carbon build up of the late 70s and early 80s was caused by the lack of computer controlld fuel injection. I already said that, YOU said it was due to the lack of lead in teh fuel. Manufacturers trying to make carburetors run lean burn through out the range of RPM and load caused a lot of too rich and too lean mixtures, which lead to incomplete combustion. And this is why there is not a lot of problem with carbon buildup with todays cars, with computerized fuel injection, fine tuning the mixture by use of O2 sensors.

Also overall gasoline makeup has changed. The gasoline you buy today is a far cry from the gasoline of the 70s, 80s or even the 90s. The mix of molecules has changed. They have reduced the aromatic (ring) componds, tightened the control over the mixture, added other molecules to do certain things. Removing lead is only one of the changes.

While water injection works (however it works a lot better under load than while running without a load) there is little reason to do it with a modern engine, since there is little carbon buildup with modern fuel injection systems.

And paragraphs still would help.

Akakubi
02-08-2004, 08:51 PM
: popcorn: Great discussion. Really enjoyed it and learned quite a bit. :thumbup:

F1Crazy
02-08-2004, 10:20 PM
The main reason for oxygenated fuel is to reduce carbon monoxide pollution, not carbon buildup. The government mandates that during cold weather oxygenated fuel is to be used in certain parts of the country that face high carbon monoxide pollution.

Sloppynwet1
02-09-2004, 12:59 AM
First off, I never said that lead engines were better. They were an additive that was used to cheapen gasoline. But lead also gave benefits. As well, engines today have additives. These additives aid in the prevention of build up. IT DOESNT PREVENT IT! My whole point was how Lead aided in this prevention. But the formulation of gasoline back then didnt have detergents to keep the engine clean. Even though cleaners are present in todays gasoline, they do not form a protective barrier against carbon build up. With age and driving habits, carbon can still build up. The only reason you do not see it as much is because of engine management systems and the addition of Detergents in gasoline. This defiantely does not allow you to compare an apple to an orange! I.E.-Engine to engine wear comparison. As well, the engines of the past , especially American made, had issues quality issues.

The name "octane" comes from the following fact:
When you take crude oil and "crack" it in a refinery, you end up getting hydrocarbon chains of different lengths. These different chain lengths can then be separated from each other and blended to form different fuels. For example, you may have heard of methane, propane and butane. All three of them are hydrocarbons. Methane has just a single carbon atom. Propane has three carbon atoms chained together. Butane has four carbon atoms chained together. Pentane has five, hexane has six, heptane has seven and octane has eight carbons chained together.

It turns out that heptane handles compression very poorly. Compress it just a little and it ignites spontaneously. Octane handles compression very well -- you can compress it a lot and nothing happens. Eighty-seven-octane gasoline is gasoline that contains 87-percent octane and 13-percent heptane (or some other combination of fuels that has the same performance of the 87/13 combination of octane/heptane). It spontaneously ignites at a given compression level, and can only be used in engines that do not exceed that compression ratio.

During WWI, it was discovered that you can add a chemical called tetraethyl lead to gasoline and significantly improve its octane rating. Cheaper grades of gasoline could be made usable by adding this chemical. This led to the widespread use of "ethyl" or "leaded" gasoline. Unfortunately, the side effects of adding lead to gasoline are:

Lead clogs a catalytic converter and renders it inoperable within minutes.
The Earth became covered in a thin layer of lead, and lead is toxic to many living things (including humans).
When lead was banned, gasoline got more expensive because refineries could not boost the octane ratings of cheaper grades any more. Airplanes are still allowed to use leaded gasoline, and octane ratings of 115 are commonly used in super-high-performance piston airplane engines (jet engines burn kerosene, by the way).

Now if you do not believe me, go to your public Library. I found this Article from the United States Department of Energy.

"Gasoline was once prepared and sold with a small amount of tetraethyl lead
blended in. Tetraethyl lead effectively prevented valve seat recession because the lead oxide that formed during the compression process served as a high temperature lubricant, preventing the potential destructive metal-to-metal contact between the valve and its seat as well as other essential engine parts. With the advances in metallurgy in the last forty years, this compound is no longer necessary for modern engines. Hence, leaded fuel was phased out about ten of fifteen years ago. The older engines can still be protected somewhat by aftermarket fuel additives that do not release heavy metals into the environment. Few measures have had the potential to protect the environment as much as the elimination of leaded fuels. Since it really isn't needed any more, why compromise health by formulating it into fuels that will be burned with minimal emission control? (The gasoline part is still the same, so unleaded fuel still burns to release the same amount of water and oxides of carbon and nitrogen per gallon, it just doesn't release lead compounds.)"

This proves my point about the comparison of older engines, the lubrication properties and technological advances.

So now onto your assumption that new engines do not get Carbon Build up!

As well, an excerpt from technical bulletin I found:

"When an engine is new it is usually very efficient. This means that when gasoline is injected into the piston chamber more of it is consumed during combustion than in an older engine. However, internal combustion engines are not very efficient, which means the fuel that is not consumed is transformed into carbon monoxide (CO) and hydrocarbons (HC) emissions. In the new engine the key word is "carbon," because the carbon also begins to build up inside the combustion chamber (cylinder walls, the top of the piston, head, and exposed parts of the valves). This process is called "agglomeration," which means forming a mass from particles that retains its individuality. The more carbon that builds up over time the less efficient the engine becomes. As the engine becomes less and less efficient it produces more and more unburned fuel or CO and HC, which speeds up the agglomeration.

The catalytic converter is responsible for burning CO and HC before they leave the exhaust and enter the atmosphere. In addition, in many new model vehicles part of the exhaust is recirculated to give the engine a second chance at burning these harmful deposits. Unfortunately, over time the catalytic converter and other systems in many vehicles loose efficiency and the engine exhausts more and more pollution"

As for the oxygenated fuel, I have ranted too much on here. Maybe next time I will cover that topic! :thumbup:

Sloppynwet1
02-09-2004, 01:07 AM
Oh, BTW, I do not remeber where I read the fact about carbon build up and detergents and lead. I will keep looking for it. My original post was based upon that fact. So, give me time, I will find it. As well, I was talking about Lead because of that fact. New engines are not carbon Free. Anyway, this has been informative!

Pinecone
02-09-2004, 03:24 AM
First off, I never said that lead engines were better. They were an additive that was used to cheapen gasoline. But lead also gave benefits. As well, engines today have additives. These additives aid in the prevention of build up. IT DOESNT PREVENT IT! My whole point was how Lead aided in this prevention. But the formulation of gasoline back then didnt have detergents to keep the engine clean. Even though cleaners are present in todays gasoline, they do not form a protective barrier against carbon build up. With age and driving habits, carbon can still build up. The only reason you do not see it as much is because of engine management systems and the addition of Detergents in gasoline. This defiantely does not allow you to compare an apple to an orange! I.E.-Engine to engine wear comparison. As well, the engines of the past , especially American made, had issues quality issues.

The name "octane" comes from the following fact:
When you take crude oil and "crack" it in a refinery, you end up getting hydrocarbon chains of different lengths. These different chain lengths can then be separated from each other and blended to form different fuels. For example, you may have heard of methane, propane and butane. All three of them are hydrocarbons. Methane has just a single carbon atom. Propane has three carbon atoms chained together. Butane has four carbon atoms chained together. Pentane has five, hexane has six, heptane has seven and octane has eight carbons chained together.

It turns out that heptane handles compression very poorly. Compress it just a little and it ignites spontaneously. Octane handles compression very well -- you can compress it a lot and nothing happens. Eighty-seven-octane gasoline is gasoline that contains 87-percent octane and 13-percent heptane (or some other combination of fuels that has the same performance of the 87/13 combination of octane/heptane). It spontaneously ignites at a given compression level, and can only be used in engines that do not exceed that compression ratio.

During WWI, it was discovered that you can add a chemical called tetraethyl lead to gasoline and significantly improve its octane rating. Cheaper grades of gasoline could be made usable by adding this chemical. This led to the widespread use of "ethyl" or "leaded" gasoline. Unfortunately, the side effects of adding lead to gasoline are:

Lead clogs a catalytic converter and renders it inoperable within minutes.
The Earth became covered in a thin layer of lead, and lead is toxic to many living things (including humans).
When lead was banned, gasoline got more expensive because refineries could not boost the octane ratings of cheaper grades any more. Airplanes are still allowed to use leaded gasoline, and octane ratings of 115 are commonly used in super-high-performance piston airplane engines (jet engines burn kerosene, by the way).

Now if you do not believe me, go to your public Library. I found this Article from the United States Department of Energy.

"Gasoline was once prepared and sold with a small amount of tetraethyl lead
blended in. Tetraethyl lead effectively prevented valve seat recession because the lead oxide that formed during the compression process served as a high temperature lubricant, preventing the potential destructive metal-to-metal contact between the valve and its seat as well as other essential engine parts. With the advances in metallurgy in the last forty years, this compound is no longer necessary for modern engines. Hence, leaded fuel was phased out about ten of fifteen years ago. The older engines can still be protected somewhat by aftermarket fuel additives that do not release heavy metals into the environment. Few measures have had the potential to protect the environment as much as the elimination of leaded fuels. Since it really isn't needed any more, why compromise health by formulating it into fuels that will be burned with minimal emission control? (The gasoline part is still the same, so unleaded fuel still burns to release the same amount of water and oxides of carbon and nitrogen per gallon, it just doesn't release lead compounds.)"

This proves my point about the comparison of older engines, the lubrication properties and technological advances.

So now onto your assumption that new engines do not get Carbon Build up!

As well, an excerpt from technical bulletin I found:

"When an engine is new it is usually very efficient. This means that when gasoline is injected into the piston chamber more of it is consumed during combustion than in an older engine. However, internal combustion engines are not very efficient, which means the fuel that is not consumed is transformed into carbon monoxide (CO) and hydrocarbons (HC) emissions. In the new engine the key word is "carbon," because the carbon also begins to build up inside the combustion chamber (cylinder walls, the top of the piston, head, and exposed parts of the valves). This process is called "agglomeration," which means forming a mass from particles that retains its individuality. The more carbon that builds up over time the less efficient the engine becomes. As the engine becomes less and less efficient it produces more and more unburned fuel or CO and HC, which speeds up the agglomeration.

The catalytic converter is responsible for burning CO and HC before they leave the exhaust and enter the atmosphere. In addition, in many new model vehicles part of the exhaust is recirculated to give the engine a second chance at burning these harmful deposits. Unfortunately, over time the catalytic converter and other systems in many vehicles loose efficiency and the engine exhausts more and more pollution"

As for the oxygenated fuel, I have ranted too much on here. Maybe next time I will cover that topic! :thumbup:

"As for leaded gas, LEAD, or rather the lack of lead in gasoline is the cause for larger amounts of Carbon Build up. Lead in our fuel helped eliminate the majority of the problems."

From your first post.

Gasoline always has had additives, they just change in speicifc additives and amounts over time.

As for your last aprt:

1) Gasoline is not injected into the cylinder on mass market cars. The gas is injected into the intake runner at the back of the intake valve. Single point injection systems inject teh fuel upstream of the manifold branching.

2) Fuel that is not consumed are HC, or unburnt hydrocarbons. CO is a a combustion product, made by combining one atom of carbon with one atom of oxygen. It is a gas, and it is flammable, since the stable form is CO2 or one atom of carbon with two atoms of oxygen. Also a gas at room tmepratute.

For carbon to build up, you have to have it in a form that can deposit. And CO an HCs (also gases at combustion temps) are not in this form.

3) Actually as carbon builds up in a cylinder head, it increases compression ratio, actually leading to more efficient combustion, unless you have pre-ignition, where a hot spot ignites the charge prior to full compression.

4) A lot of carbon build up comes from oil getting past the rings in very old engines. How old? It depends on the engine, but we ran a Jeep Cherokee 4.0 I6 for 300,000 miles, without any steps to remove carbon build up. The only reason the engine was pulled, was that the rear main seal was leaking (more like pouring out) oil. The engine had proper compression, good gas mileage, started and ran well. Older engines did have more ring leakage from the start, and typically the rings were not sealing well at all by 100K miles.

This is also why 2 stoke engines have more of a problem with carbon build up, they add oil to the gas either by pre-mixing or oil injection.

5) A catalytic converter doesn't "burn" the CO and HCs (an NOx in a three way cat), it causes oxidaton at a relatively low temperature. That's what catalysts do. They accelerate chemical reactions are lower temperatures. Yes cats run hot, but a LOT cooler than burning HC and CO. And if you don't think CO burns hot, you don't realize that most of natural gas is CO. Lead doesn't "clog" the cat, it poisons the catalyst so it no longer works. In other words, it enters into an irreversible chemcial reacion with the catalyst material (normally platinum) and changes the chemical structure such that it no longer catlyses reactions.

6) DOE is wrong, but they are a govenment agency, so it can be expected. TEL was added for octane enhancement, since it was a cheap and esy way to get more octane. The valve seat protection (not actually lubrication, but shock cushioning) was a by product of the lead in the gas. Since the lead was there, manufacturers took advanatage of it by using fairly soft steel valve seats. Lead was removed from all motor fuel because the of the EPA, and concerns over lead emissions. LOTS of press about how much lead was along the sides of this nations highways. By that time, MOST cars being built ran on unleaded only due to the having cats, so only the older cars would be effected. At the time, you could buy a lead substitue for older engines to protect the valve seats. And if you rebuilt an engine, the first change was adding hardened valve seats to cope with unleaded gas.

Once unleaded was the law of the land, the oil companies worked on increasing the octane of the fuel itself, rather than relying on TEL to do so.

Pinecone
02-09-2004, 03:28 AM
Oh, BTW, I do not remeber where I read the fact about carbon build up and detergents and lead. I will keep looking for it. My original post was based upon that fact. So, give me time, I will find it. As well, I was talking about Lead because of that fact. New engines are not carbon Free. Anyway, this has been informative!

Of course they aren't carbon free, and wouldn
t be unless you switch them to run on hydrogen.

But due to advances in all areas of engines, it is no longer a problem that had to be dealt with on a regular basis.

We no longer have as much of prolbme. In the old days, we used to pull the head a couple of times a yer to remove the carbon (hot cams, lots of carb, rich mixtures for power). Now you can run your car for 100s of thousands of miles and not have enough carbon to ever have to worry about.

Also the almost constant lean burn of modern engines contributes to the lack of carbon build up. Having a hot environment, with excess oxygen, actually consumes excees carbon as you drive.

And as I stated a LONG time ago, a lot of what people called carbon buildup was more often plug fouling. Either by lead in the old days (which responds extremely well to an Italian tune up) or oil wetting, which may or may not respond to an Italian tune up.

F1Crazy
02-09-2004, 07:25 AM
Interesting article about research done by BMW on fuels and intake valve deposits that led to introduction of BMW IVD test:http://www.swri.edu/3pubs/brochure/d08/qualify/qual.htm
It also has a lot of information explaining what causes deposit formation.

Pinecone
02-10-2004, 04:25 AM
Great article.

Intake valve desposits are a big problem. ANd are more liely in multi port fuel injection systems, since hte fuel is sprayed ont eh back of the hot intake vavle. At higher power outputs, the injector may be spraying almost 100% of the time. This leads to fuel puddling on the back of the intake valve.

This type of deposit may be due to changes in fuels, or may be due to the increase use of multiport fuel injection.

It is separate from carbon buildup inside the combsution chamber. This type of buildup does not respond to Italian tune ups, and it is not removed by using the water in the intake method. The only way to remove these deposits is to increase the amount of detergents.

Over the years, through personal trial, I have found that Mobil Super Premium tends to have a benficial effect on my cars. A tank or two of it (even in a car that burns regular) increases the gas mileage for a period of time. And makes the car run better. This may no longer be true, as gas formulations change on a periodic basis.

Chevron Techron is an excellent fuel system additive from removing both intake valve deposits and fuel injector deposits. I have heard, but am not sure, that BMW fuel system cleaner is Chevron Techron. I use BMW Fuel System Cleaner every 2K miles in the M3.

Redline is supposed to be good also. I am not sure, but I run it in the Roadster. We runa small amount (about 1 ounce per tank) pretty much all the time, due to the problems the Z3 line has with fuel tank senders.

Most of the other fuel system additives are closer to snake oil, and may work or may not work to help remove these deposits.

xspeedy
02-10-2004, 08:16 AM
You don't think every 2K is too often to run cleaner? I'm sure an occasional treatment is beneficial, but I wonder if some of the chemicals used in these cleaners can be harmful to some of the components after prolonged use.

I've never put a drop of any fuel system cleaners in my Integra after many, many miles and I have never had an issue with the fuel system. I think for the most part that the standard detergents in pump gas are sufficient.

F1Crazy
02-10-2004, 08:16 AM
Chevron sells a few different products that contain Techron and I've been fooled before when I purchased their Pro Gard products instead of Techron Concentrate. I guess I should've known better when I bought 4 bottles for what I usually pay for one... AFAIK the main difference between all these products is the concentration levels of their active ingredient Poly Ether Amine (known as Techron). The concentrate is a pretty powerful formula and I wouldn't use it more than every oil change or 5-8K miles.

I've used Red Line S1 in the past and I liked it a lot and its price even better, too bad I can't get it locally.

I've never seen BMW fuel system cleaner, how much is it?
My dealer had BG 44K additives and they work good on neglected cars but I wouldn't use it for regular maintenance plus they are pricey.

The only other product that caught my attention is Lubro Molly additive sold by bavauto.com.

Pinecone
02-10-2004, 01:28 PM
I don't feel that every 2K is too much for the BMW stuff. I wouldn't run Techron that often.

The BMW stuff is supposed to be used every tank, but that gets a bit expensive. Every 2K is about every 7 or 8 tanks.

The Redline is nice for every tank use. I use my old BMW bottles to mix up 1 ounce of Redline Fuel System Cleaner and 1.5 ounces of Redline Fuel System Water Remover. The Roadster doesn't get driven as much.

I forget how much the BMW stuff was. I picked up a case of it not long after I got the car. It wasn't that expensive with BMW CCA discount.