E65 / E66 M73 760i / 760Li misfire rough running

• Initially starting the cold engine results in what seems like a higher RPM for a minute (1300 RPM). The idle settles down and seems to run smooth and O2 readings seem to cycle normal.
• As soon as you take it above idle, the engine stumbles and misfires significantly. The engine speed is unstable and difficult to hold steady. O2 readings increase to around 0.75.
• Revving the engine up and down seems to stabilize the O2 readings with readings near zero and as high as 0.6.
• Whenever you let the car return to idle it seems to run much better but maybe not perfect.
• Recently seems much worse when it is cold but gets a little better as the engine warms up but never runs correct.
• When driving you can feel a slight hesitation when taking off from a stop as well as subtle hesitation / surging when driving. Throttle response is poor requiring heavier throttle to accelerate. Mileage seems low. Exhaust temperature at the tailpipe seems very hot.
• Spark plugs changed and all looked equal in color but were dark. Both primary O2 sensors were black. Strong revving of the engine results in a small amount of soot coming out of the tailpipe with the water vapor (no smoke at all, just minor soot).
• The intake valves have some discoloration but no coke buildup.
• All intake manifold gaskets were resealed.
• A “P301 Pending” Code exists. The spark plugs and #1 coil have been replaced.
• Exhaust backpressure was measured on bank 1 with less than 1 psi measured up to 3000 RPM.
• Some oil residue found in intake system. Both crankcase pressure control valves have been replaced.
• The engine never stalls. Full throttle acceleration seems OK (strong) but hard to say if it runs perfect.

The dealer wants to dissesemble the motor and look at both the eccentric shafts for big $. It does not make sense to me. Any Ideas?

have you checked the fuel lines and fuel pump pressure? Injectors?

This motor is direct injection. Fuel pressure is in the 400 - 500 psi range at idle and ramps up to 800+ psi as RPM's increase per my Scan Tool interface. I am not sure what the pressure is supposed to be for this motor.

Not sure if there is any reasonable method to actually check the injectors without removal?

All plugs appear to burn about the same (slightly rich). Both cylinder banks are running rich as both the O2 sensors replaced were black and the Lambda O2 readings on both sides being high when holding engine RPM above idle.

The output from throttle position looks steady although actual engine RPM's are difficult to hold steady at anything a little above idle speed.

Originally Posted by Matzan

This motor is direct injection. Fuel pressure is in the 400 - 500 psi range at idle and ramps up to 800+ psi as RPM's increase per my Scan Tool interface. I am not sure what the pressure is supposed to be for this motor.

Not sure if there is any reasonable method to actually check the injectors without removal?

All plugs appear to burn about the same (slightly rich). Both cylinder banks are running rich as both the O2 sensors replaced were black and the Lambda O2 readings on both sides being high when holding engine RPM above idle.

The output from throttle position looks steady although actual engine RPM's are difficult to hold steady at anything a little above idle speed.

Are you getting any other CEL errors besides the one code in your orignal post. If not, it seems very odd. Have you also checked the timing and timing chains and such to make sure that a guide hasn't broken?

No other errors although have not driven more than 100 miles since I purchased the car. The "P301 Pending" is the only code but will not reset with my interface for some reason.

I have not checked timing or chains. I am guessing this must be a physical check by tearing down the motor? There are no abnormal mechanical noises at all. It looks like there are dedicated chains and tensioners for each bank. Only because both banks seem to run simularly rich, I am wondering should it be something that is common to both banks?

The misfire seems substantially worse as soon as you bring the engine speed off idle.

I am using ELM Scan Tool for my ECU interface and one strange observation is that the "Fuel System Status" slowly changes back and forth between "Closed Loop" and "Not Used" for each bank but not at the same time. All the monitoring points seem to be very slow to update. I have never noticed this before with the other cars I have monitored. So far have written it off as just the way this car works with this low cost interface. But wondering if there is any reasonable possibility there is a main DME issue. But it would seem that the dealer should be able to assess this quickly? The dealer has not been very cooperative and unwilling to ask for BMW PuMA help. They so far insist on tearing down the motor to look at both the eccentric shafts for wear (based on their experience). All things considered - not convinced this makes sense.

I am not sure what to expect regarding symptoms, but some other thoughts I have had include:

- Trouble within the Direct Injection Control Unit?
- Issue with the Carbon Canister System?
- Tank Vent Valve?
- Secondary Air System?

Originally Posted by Matzan

I am not sure what to expect regarding symptoms, but some other thoughts I have had include:

- Trouble within the Direct Injection Control Unit?
- Issue with the Carbon Canister System?
- Tank Vent Valve?
- Secondary Air System?

The only thing that I can think of quickly is to check all the vacuum lines and also see how much suction there is at the oil cap. To much suction and that means something is wrong.

That P301 code means cylinder 1 misfire. Did the car do this from the day you bought it? If yes, the previous owner may have let it go for this reason. Have them do a compression check and make sure it comes back okay. For some reason I'm thinking that you may have a bent rod or something from the car being hydrolocked.

Does the motor itself vibrate a bit? If yes, that isn't normal. You should be literally able to balance a quarter on it's side on the center of the engine with it running.

I met with the BMW shop Foreman and their best mechanic today. They are finding a number of issues with the V-8 related to the eccentric shaft wearing that shows symptoms of rough idle and misfire codes. They actually were able to show one repair in progress and I could actually see the wear. It was an X-5 with the 4.4 and only 70,000 miles. As the design is essentially the same for the N73 V-12, they have strong suspicion that this is the same cause of my cars rough idle and misfire. A little more research reveals that the Valvetronic system utilizing the eccentric shaft has a significant impact on controlling engine speed. So bottom line, I approved the cost to pull the intake and valve cover to confirm the eccentric shaft condition. Should have results in a couple days.

I have a similar issue but never spits any code out, cold starts cause the engine to idle up then down to low to the point of cutting off, after removing the key and open/close door I can start it back up and no more problems once engine reaches warm. the dealer said it was one of the HPFP which they want 4000 for, I'm going to let my mechanic look at it when I have time.

Originally Posted by bigwalk

the dealer said it was one of the HPFP which they want 4000 for, I'm going to let my mechanic look at it when I have time.

I had the same problem last year and indeed it was the High pressure fuel pump. The car would surge up and down in the morning when it was cold, once warmed up it would go away. It took the dealer a month and a half to finally figure out the problem and it did turn up to be the HPFP. At the end they wind up spending close to $10k, glad the car was still under warranty.

Here is the latest. Dealer has finally opened up the motor deep enough (removed valve cover) to identify wear on the eccentric shaft. Dealer quoted $6835 parts and $3000 labor to repair the engine or $900 to simply put it back together. The motor internals are crystal clean verifying the records that show dilligent oil changes sooner than recommended by BMW. The dealer tells me they are repairing three cars a week that need new eccentric shafts. Some are failing as early as 70,000 miles. Fortunately for most, repairs are covered under warranty. Unfortunately, mine is not. I am told BWM rep will not consider any help from BMW on repair as I am not the original owner. I am an engineer with extensive engine and mechanical design experience and have built several high performance engines from pan to carb (Pontiacs and Chevys). There is no question in my mind that BMW has a deficient design regarding the eccentric shafts used in their engines. I am now looking into what other options I have to get this car running properly.

Oh - interesting thing I noticed while reviewing parts list... It includes a new air pump and vent pipe?! Could this be the cause of my rough running and misfire? The initial response from the service advisor is that the air pump only runs during warm up - but does this make sense? Anyone have experience with this???

Originally Posted by Matzan

Here is the latest. Dealer has finally opened up the motor deep enough (removed valve cover) to identify wear on the eccentric shaft. Dealer quoted $6835 parts and $3000 labor to repair the engine or $900 to simply put it back together. The motor internals are crystal clean verifying the records that show dilligent oil changes sooner than recommended by BMW. The dealer tells me they are repairing three cars a week that need new eccentric shafts. Some are failing as early as 70,000 miles. Fortunately for most, repairs are covered under warranty. Unfortunately, mine is not. I am told BWM rep will not consider any help from BMW on repair as I am not the original owner. I am an engineer with extensive engine and mechanical design experience and have built several high performance engines from pan to carb (Pontiacs and Chevys). There is no question in my mind that BMW has a deficient design regarding the eccentric shafts used in their engines. I am now looking into what other options I have to get this car running properly.

DAMN!

10gs to fix it.

WOW.

i have nothing else to say

I'm a BMW tech myself and currently diagnosing this exact same issue on a 760. The problem is the high pressure fuel pump. There are 2 one on each bank. From what I'm seeing and what you discribe also, I would bet the bank 1 pump is failing. It is a pricey part at almost $2500 and 10+ hours to install.
I would doubt very highly the eccentric shafts are to blame. I've never had that repair actually fix anything, as the ones with the bad rockers/shafts also had bad head castings. Those were also N62's, which while slightly similar are nothing alike in operation.
Ask/tell them to check the HPFP's since the intake is off already it shouldn't be a big ordeal.

~Lewthor

Interesting read. I have a similar issue upon cold-start in the morning. '06 e65 idles to about 1300, warms up, then down to 500. However, during the rough idle, the entire car sounds like a NASCAR rig, and the whole car rumbles from side-to-side for about 10 seconds. So rough if you put a full cup of coffee on the dash it will certainly spill. After warm up, I put the car in reverse and back out of my garage. While doing so, the brakes feel like they are pumping as the car surges backward, then pauses, then surge, then pause. All happening simultaneously (surging/pausing).

Once the car is in drive, just for about 500 yards, I give it gas but it feels like it doesn't want to go. My 1st thought was fuel pump. After a couple minutes, all is good. Car runs fine. But same scenario every morning.

Do apologize as my intentions are not to thread jack. But I feel the 2 issues are quite similar. Hoping mine if the fuel pump, and not the $10k fix. Though, I'm under GMPP w/ a $50 deductible. Regardless, still sucks.

Update - Some miscommunication regarding need for an air pump. They are telling me it does not need an air pump, just the hose that has some damage. They are adamant that the primary problem is the eccentric shafts. I am also planning to ask about checking the fuel pressure as suggested.

So far we have negotiated down to $100 / hr. for labor. Service Advisor tells me they should be charging $150/hr. for a big job like this (What?!)... Also trying to reduce the total labor hours from 30 down to something less as they are not replacing as many parts as teh original plan. I eliminated replacement of unrelated parts such as lifters, rocker arms, spark plug tubes, etc... The only parts to be changed will be the eccentric shafts themselves and the related intermediate shafts along with gaskets and a couple of unrelated hose assemblies. If a spark plug tube breaks or a roller bearng breaks then those will be replaced as necessary. The other big hit was vigerously negotiating the price for parts. They started with prices well above list prices and then after asking for BMWCCA discount... they were still freakin above the damn list price!!! After I told them I had quotes from Circle BMW at 15 - 20% below list - the parts guy agreed to match their prices. Still have not received a final quote yet but probably still looking at $6000 or more with taxes. WIll update as we progress.

It occurred to me earlier that the way they diagnosed the eccentric shafts was flawed. To check them, you unplug the motors. You don't remove valve covers to "look" at them. Even holding them in your hand next to a new on, you can't see anything different about them. The shafts themselves weren't the problem either, it's the intermediate levers. Warranty would replace everything because why not it's the same labor to do everything. But, when it's your dollar buying the parts I'd want to just replace the parts that fail not the whole system.

The intermediate levers (but not the eccentric shafts or anything else) have been replaced - total cost for this and a couple other items ended up at $5300. There is visible wear on the levers and they fall within the manufacturing dates that have been deemed defective (for the original owner only). The wear seems very minor but perhaps very minor wear can cause significant issues. I could not see or justify how the eccentric would wear as it contacts the intermediate levers via a roller contact. The intremediates are a documented wear problem and wear can be seen on them. Initially, the car seemed maybe 50% better. Brought it back as there is also a minor raw gas leak someplace around the engine. They tried re-programming but claim that the latest software has already been loaded. The mechanics think it runs fine considering it has 109,000 miles and have no other ideas on what to try other than pulling apart the motor to look deeper. I have been driving it all week and feel that it is maybe 90% better but can't say it runs perfect. There is still a faint hesitation and then surge as you take off most of the time. The motor definitely runs smoother but not perfect. The engine speed just above idle is much more stable but not perfect. Initially as the car excellerated moderately, you could feel a very subtle hesitation and surge as it went. That seems to have improved. Not sure if the computer is still adjusting for the intermediate lever change or I'm just getting more tolerant or used to the running characteristics. Although they worked on the gas leak and made some improvement, there is still a faint raw gas odor after the car is shut down. I probably will have to pull the intake again and fix it myself as that is probably less hassle than bringing the damn thing back to the dealer and arguing again that there is a gas leak.

Not my place to say, as I have not mechanical education. However, regarding the "slight hesitation and surge", once my oil leak and vacuum were fixed, I no longer experienced the same issue I had prior to the fix.

I have had similar problems. I found a computer reset helped.
Proceedure:
Ignition on but engine off
Depress accelerator to floor for 20 seconds
Release accelerator and start engine normally
I found my surging while cold disappeared after doing this. I need to repeat this process at least every few weeks as the surging will return.

Hope this helps,

If anyone of you is interested I happen to have one of these HPP's.
Its part # 13-51-7-529-068
It fits up to 09/06
If interested we can do the deal through Paypal to keep everyone safe.

I had exactly this fault and it turned out to be the fuel pressure sensor on the left hand rail. Initially they said it was the HPFP and they did change it, but it did not fix the fault. They then found that the fuel pressure sensor on the left hand rail had gone to ground so it was giving no reading to the DME at all, hence the car farted around...... all good now since the fuel pressure sensor was replaced.

Originally Posted by Lewthor

I'm a BMW tech myself and currently diagnosing this exact same issue. The problem is the high pressure fuel pump. There are 2 one on each bank. From what I'm seeing and what you discribe also, I would bet the bank 1 pump is failing. It is a pricey part at almost $2500 and 10+ hours to install.
I would doubt very highly the eccentric shafts are to blame. I've never had that repair actually fix any0lithing, as the ones with the bad rockers/shafts also had bad head castings. Those were also N62's, which while slightly similar are nothing alike in operation.
Ask/tell them to check the HPFP's since the intake is off already it shouldn't be a big ordeal.

~Lewthor

I changed my plugs and put intake manifold back on just as was. Ok fired her up, it ran fine at first. Test drove and then check engine, idrive screen emission related fault service engine soon. Rough idling starts from this point on. Code reader from AutoZone reads P0302-misfire cylinder #2Removed plug and coil from cylinder #2. Plugs are new and wires look fine. Plug has black carbon on the bottom and was a little damp with gas.
Do you have any idea why cylinder #2 is misfiring.
Also when reinstalling the 760 intake manifold is there a tightning sequence to bolting it back on?

I have a 2004 760LI. I saw your post recently on the misfire codes. I like you took off the intake and replaced the coils and the plugs. I put everything back together and it was the same codes showing up.

I am hoping that we can collaborate as we discover what the root cause is for both of us.

The torque value for the intake is 15nm and the sequence the indie tole me to use was, snug center out before torquing. Then alternate side to side from center to outer bolts until at right torque.

Elliott.

Still haven't solved issue, broke down engine yesterday remove plug on number 2 cylinder, checked ground wire, ok and check the fues for that injector and all checked out fine. Also checked wire connector that attaches to coil with my multimeter and it is receiving power. Now I am thinking about checking the fuel presure sensor and then the injector and finally the high presure fuel pump but I hope and prey it does'nt go that far because I heard that high presure fuel pump is $$$. Let me no what progress you have had?