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High RPM power loss (M30)

15K views 54 replies 10 participants last post by  Mamij 
#1 ·
As some of you may know I have limited knowledge on cars, but I gave it a bit of a tune up in the summer. I always used Shell gas until about 2 weeks ago. It accelerated good until about 4000 RPM (2nd gear) and it would start choking up and lose power. I've recently put BP gas in and the choking after 4k stopped, but I still feel that it's not pulling as quick in second gear as it should. I compared it to my mom's e39 525i and hers seems to accelerate quicker than mine so that's why I feel a bit concerned. Could you guys give me ideas on what you guys think?

Ps:I'm in need of an oil change. The air filter I have was given to me (This summer) for free but it was used and looks a bit dirty.

Thanks guys
-Dionte
 
#4 ·
I'm not sure, I've been driving this for a few months now, as this was my mother's previous car. But I don't believe she's gotten anything much done to it besides general maintenance. I was thinking it could be a valve adjustment because my mother doesn't even recall having a valve adjustment service when she owned it. Some people online say that I should clean the MAF.
 
#5 ·
Sounds like a fuel pump on the way out. Filling the tank with fresh cool gas is what made it work again.

I would second the valve adjustment, just good maint.
 
#6 ·
Ok,

Hi RPM loss to me rules out a vacuum leak..

Things that get worse with RPM tend to be Fuel or spark related.
 
#10 · (Edited)
Yeah, I did vacumm lines this summer, I just noticed that the air intake boot has minor hidden cracks that are hard to see. Maybe this is causing the power issue at climbing RPMs, not sure though. Appreciate everyone's input so far.

Edit: I forgot that Sled mentioned the fuel pump, since I've been running BP gas I did notice a slight different at first but then it came back.

Sent from my SGH-T839 using BimmerApp mobile app
 
#8 ·
#9 ·
Do a valve adjustment. It's the cheapest out of all of the possible solutions.

Things to look into with the other issue (most have been said)

Distributor
Rotor button
Plugs
FPR
Fuel Filter
Fuel pump

AFM is a possibility but you'd feel it way before you hit 4k on the tach.
 
#11 ·
It could be, but that should be worse at lower RPM's
 
#12 ·
ANY air leak into the intake will screw with the EFI computer and performance. I would check fuel pump flow rate too; as you are leaning out at the top end.
 
#13 ·
I just started paying more attention and it seems that it performs better when the engine is cold. Once it reaches operating temperature is when I begin to lose power in the higher RPMs. Fuel pump, as someone previously mentioned?

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#14 ·
Sounds like 02 to me..
 
#16 ·
Check the larger vaccum pipe on the front of the intake manifold.



It's the larger pipe dead center in this pic.

They tend to become brittle and crack. It can cause what your speaking of.

Also as I mentioned and others do the valve adjustment.
It will eliminate mechanical failure as the culprit. A unbalanced adjustment will cause hi end power loss. If not done already grab a downloadable copy of the Bentley manual from the "bible" thread. It will guide you through it. As well there are literally tons of DIYs on the subject which will help you do the job correctly.
 
#18 ·
Dionte. You can get your hands dirty on this.
It's so simple it kind of defeats the purpose of going to the shop.

All you need tool wise is a 10mm socket, 10mm box or open end wrench, screw driver, a coat hanger and about 4ft of speaker wire.

Then follow this DIY:
M30 Valve adjustment

And you can Get it done under 45 mins to an hour.
 
#19 ·
Yes, I was planning on performing the job myself at the shop. I used to go there often in the summer, so I can use the tools if I need them. Sorry for the confusion.

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#20 ·
Since I still think your fuel pump is on the way out, I would keep the fuel tank over half full until you find the culprit for sure. If the car stalls out on you, letting the pump cool a while will sometimes allow you to re-start and get somewhere where you can work on it.

You can do the valve adjustment in 45 minutes but your first time might take double that. I know I took longer than 45 mins when I did mine;)
 
#22 ·
I'm positive its the fuel pump. Been having starting issues lately and its been stumbling upon accelerating. It has 210k miles on it so it was a matter of time I guess.
But I also noticed that its been idling a bit high & lumpy and the CEL comes on around 2000 RPM but then disappears. Also smells like gas badly at idle as if my o2 sensor is going bad again even though I replaced it last summer.

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#23 · (Edited)
Hi Dionte,

There are two sets of advice I can give you about this issue. The first one will help you troubleshoot and fix this particular problem alone, and will stop there. The second one will give you lasting peace over the years and leave you with the question why isn't everyone experiencing this?

Part 1


1. Do the stomp test. If this doesn't work despite your best efforts, get code reading software and OBD1 cables. $50 off ebay, and well worth the investment because you'll need it to take care of this and other BMWs you'll own down the line. If you find any codes, take note, disconnect the sensor involved (if it is a drivability sensor) and test your car to see if these problems have been resolved. If they have, then replaced that sensor and you're done.

2. Change the fuel filter if you've not done so before. It might be 100k old. Fuel filters used well past their service life are difficult to be successfully rinsed with water. GmnmsclM540 tried it and it didn't work. Newer filters can be rinsed out with water every 12-18 months for the next 7-10 years. Roberto did this and it works perfectly.

3. Clean your throttle position sensor's switch contacts and connector contacts. Use contact cleaner and toothbrush.

4. If the starting and drivability problems remain, and there are no useful error codes, proceed to do the disconnect test for all your drivability sensors (ects, tps, ats, icv, afm). Once this reveals the bad sensor, change it to a new oem or oem grade unit.
 
#25 · (Edited)
I read through your thread. You mother did not trash the car at all, but she is not an enthusiast if she can't recall when she did a valve adjustment or refer you to her regular mechanic who can tell you that.

That means you have a 210k old E34.

Now you have two choices. You can continuously, over the next 3 years, make posts to the list asking for help with running problems, with no start issues, and other stuff, or you can do it all ahead of time at one go, sit back, relax, and wonder why other people are making such posts.

The difference is just $500 in *oem* parts and about 1 day of DIY time on your end that I know you have the capability to do. By the end of next weekend, you can be that guy who has a reliable E34 that drives superbly. If you don't have the money for this right now since you're in school etc, borrow it from you mother or someone and pay her back over the next 6-12 months.

I think you're one of the more intelligent young guns on the list, in contrast to others who drift in the darkness and nearly kill their girlfriends and try to pass it off as cool. I hope you make the right choice.

All that I'm going to recommend to you here concerns components that either WILL go wrong on an old bmw, or WILL be at less than optimal levels, enough to cause poorer fuel economy, engine performance, or a host of unpredictable and difficult to pinpoint behaviours from time to time. $500 is small beer compared to the original cost of your E34 which was $40,000. The costs of repair are so low because we can tell you exactly what is needed, and practically everything here is a DIY job so you save on workshop charges.

I've been on this list for many years and have owned an E30, E34 and an E36. Trust me when I say that I've been through it all. I am certain about what I'm talking about. Its easier and better to do it all at one go.

==================

First, kill your common no start issues (and everything here is oem unless otherwise stated).

1. Fuel pump. $110 shipped Bosch.
2. CPS. $60-$90, either valeo, bosch or meyle.
3. Fuel pump relay. $15.
4. Check your battery's reserve charge / cold cranking amps (CCA) on an appropriate digital meter. Usually just a small tip or for free at a shop, autozone and about 10 minutes work. If its under 35%, you need to revive your battery ($40 for the kit), or purchase a new one.

Check your suspension bushings. If they are not bad, and if in doubt consult us over here, then go onto the following :

Maintenance

5. Clean out your air filter (Please see. ) or change it to a new one $15.
6. Change to a new fuel filter $20. Very old fuel filters cannot be rinsed out from what we've seen.
7. Change your ects. $25.
8. Change your ats (air temp sensor). $20-$25.
9. Change or seal up your intake boot and your vacuum lines. Anything from $5 (silicone high temp non-gasket sealant) to about $80 for the whole set of various hoses. Not essential, but highly recommended. Check everything else.
10. Do your valve adjustment. New valve cover gasket ($25) and shim tools required (not sure how much but not expensive. If its expensive borrow from MSD).
11. Clean your plugs if they don't look damaged. Better if you get new ones if these are old. Copper ones will be fine ($20 for a set) and Bosch Plat+4s highly recommended ($45)
12. Check your rear differential fluid. If its dark or black, change out. Your fuel economy will improve, and your rear diff bearings and gears will not get destroyed. Costs $10-$20.
13. Diesel flush your engine at the next oil change. Add diesel 3 quarts of diesel to your empty fuel tank with an immediate full fillup, at the fillup following the filter change, for fuel injector cleaning.
14. Clean your throttle body off all carbon.
15. Clean out your ICV.
16. Change the one way valve on the brake booster. $15. Optional but recommended : change the brake booster's vacuum hoses, clamps, plastic fitting and rubber grommet. Will cost an additional $30-$40.
17. Get a new throttle position sensor. $45. Safety issue. Old sensors have been known to cut out the engine while driving.
18. Step down your blower motors fuse to 20A. This can help prevent fires. It is currently 30A.
19. If you recently flushed and replaced your coolant, add 1 quart of 40% concentrate sodium silicate to your expansion tank ($10 from a pharmacy) and run the engine at idle for 30 minutes. If not, wait till your next flush and coolant refresh and do so at this time. Sodium silicate seals micro cracks and tears in HGs and cylinder heads, and is coolant friendly. This is cheap insurance for your engine.
20. Consider tuning your AFM. MSD will explain further.
23. Clean your ccv fitting and test for vacuum leaks on it.

I just did a tally. All of the above comes up to $455 if I exclude optional items and the battery. Looks like I'm 13% under budget. ALL OEM-GRADE PARTS. Cost of parts? Around 1.1% of the original purchase price of this car, and that will give you headache free motoring for the next 7-10 years. And doing all the above will save you money at the gas pump through better fuel economy and will give you more driving pleasure through better performance, which is worth the investment anyway.

Oh dear. Forgot. You have the M30. The following applies to all timing belt engines (M20, M30).

14. Highly recommended that you get a new dizzy cap and rotor. You don't need new wires. However, this would not be cheap - $100-$200 oem. So you can wait till you have a problem if you wish. Consult MSD about when this is necessary. He may know how to efficiently and accurately test your existing units.
15. Timing belt ($20) and bearings (not sure but at least $50), depending on how old yours are. Consult MSD about when this is necessary. When it is necessary, it is necessary and not optional.

Please order all of the parts above and get it done all at one go for maximum efficiency (and also to probably enjoy maximum discounts). Or schedule to do them progressively over the next 12 months. Don't wait for a problem. That's silly when there's so much corroborating evidence about these cars accumulated independantly and over many years.

Good luck.
Good to see old " DB Baggio" back at it!

Why not just replace the whole car to start! Thats helpfull...
OP - be aware this guy is not accredited by this forum AT ALL!

And just becuase you have no skill's does not give you right to judge.. There was nothing close about it.. She sure thought it was cool. Sooo Quit being a lil hater you bitch..

"Drifts in the darkness" lol:thumbup: like the sound of that.

(In the dark it was not my GF fyi...)

I may use that at a further date, thanks!
 
#24 ·
I read through your thread. You mother did not trash the car at all, but she is not an enthusiast if she can't recall when she did a valve adjustment or refer you to her regular mechanic who can tell you that.

That means you have a 210k old E34.

Now you have two choices. You can continuously, over the next 3 years, make posts to the list asking for help with running problems, with no start issues, and other stuff, or you can do it all ahead of time at one go, sit back, relax, and wonder why other people are making such posts.

The difference is just $500 in *oem* parts and about 1 day of DIY time on your end that I know you have the capability to do. By the end of next weekend, you can be that guy who has a reliable E34 that drives superbly. If you don't have the money for this right now since you're in school etc, borrow it from you mother or someone and pay her back over the next 6-12 months.

I think you're one of the more intelligent young guns on the list, in contrast to others who drift in the darkness and nearly kill their girlfriends and try to pass it off as cool. I hope you make the right choice.

All that I'm going to recommend to you here concerns components that either WILL go wrong on an old bmw, or WILL be at less than optimal levels, enough to cause poorer fuel economy, engine performance, or a host of unpredictable and difficult to pinpoint behaviours from time to time. $500 is small beer compared to the original cost of your E34 which was $40,000. The costs of repair are so low because we can tell you exactly what is needed, and practically everything here is a DIY job so you save on workshop charges.

I've been on this list for many years and have owned an E30, E34 and an E36. Trust me when I say that I've been through it all. I am certain about what I'm talking about. Its easier and better to do it all at one go.


==================

First, kill your common no start issues (and everything here is oem unless otherwise stated).

1. Fuel pump. $110 shipped Bosch.
2. CPS. $60-$90, either valeo, bosch or meyle.
3. Fuel pump relay. $15.
4. Check your battery's reserve charge / cold cranking amps (CCA) on an appropriate digital meter. Usually just a small tip or for free at a shop, autozone and about 10 minutes work. If its under 35%, you need to revive your battery ($40 for the kit), or purchase a new one.

Check your suspension bushings. If they are not bad, and if in doubt consult us over here, then go onto the following :

Maintenance

5. Clean out your air filter (Please see. ) or change it to a new one $15.
6. Change to a new fuel filter $20. Very old fuel filters cannot be rinsed out from what we've seen.
7. Change your ects. $25.
8. Change your ats (air temp sensor). $20-$25.
9. Change or seal up your intake boot and your vacuum lines. Anything from $5 (silicone high temp non-gasket sealant) to about $80 for the whole set of various hoses. Not essential, but highly recommended. Check everything else.
10. Do your valve adjustment. New valve cover gasket ($25) and shim tools required (not sure how much but not expensive. If its expensive borrow from MSD).
11. Clean your plugs if they don't look damaged. Better if you get new ones if these are old. Copper ones will be fine ($20 for a set) and Bosch Plat+4s highly recommended ($45)
12. Check your rear differential fluid. If its dark or black, change out. Your fuel economy will improve, and your rear diff bearings and gears will not get destroyed. Costs $10-$20.
13. Diesel flush your engine at the next oil change. Add diesel 3 quarts of diesel to your empty fuel tank with an immediate full fillup, at the fillup following the filter change, for fuel injector cleaning.
14. Clean your throttle body off all carbon.
15. Clean out your ICV.
16. Change the one way valve on the brake booster. $15. Optional but recommended : change the brake booster's vacuum hoses, clamps, plastic fitting and rubber grommet. Will cost an additional $30-$40.
17. Get a new throttle position sensor. $45. Safety issue. Old sensors have been known to cut out the engine while driving.
18. Step down your blower motors fuse to 20A. This can help prevent fires. It is currently 30A.
19. If you recently flushed and replaced your coolant, add 1 quart of 40% concentrate sodium silicate to your expansion tank ($10 from a pharmacy) and run the engine at idle for 30 minutes. If not, wait till your next flush and coolant refresh and do so at this time. Sodium silicate seals micro cracks and tears in HGs and cylinder heads, and is coolant friendly. This is cheap insurance for your engine.
20. Consider tuning your AFM. MSD will explain further.
23. Clean your ccv fitting and test for vacuum leaks on it.


I just did a tally. All of the above comes up to $455 if I exclude optional items and the battery. Looks like I'm 13% under budget. ALL OEM-GRADE PARTS. Cost of parts? Around 1.1% of the original purchase price of this car, and that will give you headache free motoring for the next 7-10 years. And doing all the above will save you money at the gas pump through better fuel economy and will give you more driving pleasure through better performance, which is worth the investment anyway.

Oh dear. Forgot. You have the M30. The following applies to all timing belt engines (M20, M30).

14. Highly recommended that you get a new dizzy cap and rotor. You don't need new wires. However, this would not be cheap - $100-$200 oem. So you can wait till you have a problem if you wish. Consult MSD about when this is necessary. He may know how to efficiently and accurately test your existing units.
15. Timing belt ($20) and bearings (not sure but at least $50), depending on how old yours are. Consult MSD about when this is necessary. When it is necessary, it is necessary and not optional.



Please order all of the parts above and get it done all at one go for maximum efficiency (and also to probably enjoy maximum discounts). Or schedule to do them progressively over the next 12 months. Don't wait for a problem. That's silly when there's so much corroborating evidence about these cars accumulated independantly and over many years.

Good luck.
 
#37 ·


Now that thats done, please let this poor OP get back to his thread..
Its been made clear everything you say is a joke and im tired of trying to keep up with that much humor.

Please find another place to make a pointless 3 page post. And let this one help the OP now.
 
#41 · (Edited)
Hmmmmmmmmmm... Well first, thanks for the video.. Most people refuse when we need it lol.

Its a major stumble and or miss around 2500-3500 rpm..

It sure sounds and feels like ignition failure or timing issue's IMO, but that should get worse and worse as rpms rise. It sounded a little better at 5000rpm though.so wierd. Fuel shortage should get worse at higher RPM also..

Id definitly check the plugs, wires, rotor. Valves adjusted?

Specifically look for oil on or around the plugs.

And vacuum leaks, check AFM, intake boots, brake booster hose ect..

Just some tossed out idea's to consider while feeling the issue..
See if any seem to fit the build just right.
Plugged catylist?
Bad injectors
Failing fuel pump
Clogged fuel filter
Bad FPR
AFM door stuck/ bad AFM/ dirty slow AFM
 
#42 ·
Just a little update, haven't ordered the fuel pump yet. But can a bad fuel pump really cause poor gas mileage and blue smoke to come out the exhaust?

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#43 · (Edited)
Ok...
after a brief chuckle due to the back and forth between Ima and Mamji.
I listened to the start up noise.
It sounds like your running a little rich. Your either not enough air getting in there to level out your AFRs. Or your spark is the issue.
Possible culprits AFM and throttle plate. Could be the coil or distributor & rotor button.
But I doubt it's the fuel pump. (I could be wrong but I had this issue once before)
Now is this only during cold start up or does it happen all the time?
 
#44 ·
It only occurs during cold start up and once warmed up and driven around a bit it idles around 1000 RPM for at least 10-20 seconds before it starts to go down to normal idle speed when I'm at a complete stop. It also has a difficult time restarting once its been warmed up.

Now that you mention the AFM, I did swap mine a few weeks back with another 535i that just sits at the shop. We figured it would fix the high RPM power loss issue, which it did at first because in ran it afterwards without any issues. Then the issue came back. So could the AFM I swapped be faulty and causing then idling issue?

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