My 335 is at 187,000 and probably 80,000 on the current HPFP. Between this and the electric water pump with the same mileage, I'm wondering if I want to take it on a 2000-mile trip in December.
Long shot - need help with Mercedes
- Thread starter DriveHard
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Well, she is at the shop now...
The problem continued to get worse the last two days, with today being the worst. The lower the engine RPM, the worse it ran. To maintain even 55 mph I had to downshift to 3rd or 4th. At those high rpm's she had plenty of power and ran fine. To me, this points even more at a failing HPFP that relies on engine speed to turn the pump. My guess is the higher engine speeds were needed to maintain adequate fuel pressure.
Anyways...the shop told me it would be done by tomorrow. I will be on business until Friday, but will update when I get her back and drive it around a bit.
The problem continued to get worse the last two days, with today being the worst. The lower the engine RPM, the worse it ran. To maintain even 55 mph I had to downshift to 3rd or 4th. At those high rpm's she had plenty of power and ran fine. To me, this points even more at a failing HPFP that relies on engine speed to turn the pump. My guess is the higher engine speeds were needed to maintain adequate fuel pressure.
Anyways...the shop told me it would be done by tomorrow. I will be on business until Friday, but will update when I get her back and drive it around a bit.
Update...getting frustrated...
I drove the car to the shop last week. It continued to run worse and worse on the 15 mile highway drive to the point I had to downshift and keep the rpm's quite high to even get it there.
The shop replaced the fuel pump
Engine went from random misfires on most of the cylinders to only a misfire on cylinder 4
Spark plug was coated with carbon and the shop said the coil tested "sketchy"
Shop performed compression and leakdown testing on cylinder 4 - both checked out perfect
I figured it was carbon fouling causing that cylinder to misfire...asked them to put it back together and drove it home. Got 25+ mpg for the first time in a very long time. Besides the misfire on 4, seemed to be running pretty good.
Parked the car and ordered new plug and coil for cylinder 4.
Replaced them tonight...misfire persists.
Compression is good, fuel pressure is now good, new plug, new coil...it HAS to be the fuel injector.
Guessing the failure of the pump has wiped out the injector in 4...and probably damaged the others as well.
Going to replace either all 6, or start with number 4. I will keep you posted.
I drove the car to the shop last week. It continued to run worse and worse on the 15 mile highway drive to the point I had to downshift and keep the rpm's quite high to even get it there.
The shop replaced the fuel pump
Engine went from random misfires on most of the cylinders to only a misfire on cylinder 4
Spark plug was coated with carbon and the shop said the coil tested "sketchy"
Shop performed compression and leakdown testing on cylinder 4 - both checked out perfect
I figured it was carbon fouling causing that cylinder to misfire...asked them to put it back together and drove it home. Got 25+ mpg for the first time in a very long time. Besides the misfire on 4, seemed to be running pretty good.
Parked the car and ordered new plug and coil for cylinder 4.
Replaced them tonight...misfire persists.
Compression is good, fuel pressure is now good, new plug, new coil...it HAS to be the fuel injector.
Guessing the failure of the pump has wiped out the injector in 4...and probably damaged the others as well.
Going to replace either all 6, or start with number 4. I will keep you posted.
As a side note, I plan on running only premium in this car in the future...along with a nice dose of TCW-3 in the future. I can't wait for this saga to be done.
DriveHard said:
Originally Posted By: meep
this is a long thread - has valve timing/clearance been considered as a possibility?
Right now all the cylinders are running fine except number 4. The engine seems to be running really well except for that one cylinder misfire. I would assume if it were cam position or timing it would be effecting more than one cylinder. It also has cam phase control and position sensors on all 4 cams, so I would also assume it would be throwing a code if they were not in the position being commanded. The shop also did a leakdown test that showed the cylinders and valves are all sealing within specification, so the valves are closing correctly as well.
this is a long thread - has valve timing/clearance been considered as a possibility?
Right now all the cylinders are running fine except number 4. The engine seems to be running really well except for that one cylinder misfire. I would assume if it were cam position or timing it would be effecting more than one cylinder. It also has cam phase control and position sensors on all 4 cams, so I would also assume it would be throwing a code if they were not in the position being commanded. The shop also did a leakdown test that showed the cylinders and valves are all sealing within specification, so the valves are closing correctly as well.
M276 engine? As in direct-injected?
You should be able to pull that injector and test it. Low fuel pressure won't hurt it directly. What will is crud in the fuel. Soot may affect the injection pattern on DI engines, which would give a misfire as well.
The number 1 thing to check is the wiring. Weak pulses to the injectors because of something grounding somewhere, water getting into one of the connectors, corroded contacts. Same with the coils. VW products are so famous for this that even in school we called that wiring biodegradable. Mercedes and BMW are also vulnerable to it, but less to (in general).
And yes, cam phase actuation and other issues will throw a different code, or a collection of codes. No need to replace all of the injectors.
You should be able to pull that injector and test it. Low fuel pressure won't hurt it directly. What will is crud in the fuel. Soot may affect the injection pattern on DI engines, which would give a misfire as well.
The number 1 thing to check is the wiring. Weak pulses to the injectors because of something grounding somewhere, water getting into one of the connectors, corroded contacts. Same with the coils. VW products are so famous for this that even in school we called that wiring biodegradable. Mercedes and BMW are also vulnerable to it, but less to (in general).
And yes, cam phase actuation and other issues will throw a different code, or a collection of codes. No need to replace all of the injectors.
Ok, I pray this is my final update...
Only drove the car one more time, and the misfire was intermittent. This means it was not just a carboned injector...they were failing. Had all six replaced, if the failure of the HPFP caused one injector to go bad...I am sure the others were not far behind. You have to pull the intake manifold, and I just could just see myself right back in the shop in a few weeks having another injector replaced, so I did all six.
Well, just got a call from the shop. The car is back together, and running better than ever.
So in summary...HPFP failed and took out one or more of the injectors. The only wasted money was when I replaced the coils (the plugs were due anyways).
Total Parts ~$2000
Total Labor ~$1000
I pray this is the end of this saga.
Only drove the car one more time, and the misfire was intermittent. This means it was not just a carboned injector...they were failing. Had all six replaced, if the failure of the HPFP caused one injector to go bad...I am sure the others were not far behind. You have to pull the intake manifold, and I just could just see myself right back in the shop in a few weeks having another injector replaced, so I did all six.
Well, just got a call from the shop. The car is back together, and running better than ever.
So in summary...HPFP failed and took out one or more of the injectors. The only wasted money was when I replaced the coils (the plugs were due anyways).
Total Parts ~$2000
Total Labor ~$1000
I pray this is the end of this saga.
Originally Posted By: DriveHard
Ok, I pray this is my final update...
Only drove the car one more time, and the misfire was intermittent. This means it was not just a carboned injector...they were failing. Had all six replaced, if the failure of the HPFP caused one injector to go bad...I am sure the others were not far behind. You have to pull the intake manifold, and I just could just see myself right back in the shop in a few weeks having another injector replaced, so I did all six.
Well, just got a call from the shop. The car is back together, and running better than ever.
So in summary...HPFP failed and took out one or more of the injectors. The only wasted money was when I replaced the coils (the plugs were due anyways).
Total Parts ~$2000
Total Labor ~$1000
I pray this is the end of this saga.
That's wonderful. I hope this is all behind you.
Ok, I pray this is my final update...
Only drove the car one more time, and the misfire was intermittent. This means it was not just a carboned injector...they were failing. Had all six replaced, if the failure of the HPFP caused one injector to go bad...I am sure the others were not far behind. You have to pull the intake manifold, and I just could just see myself right back in the shop in a few weeks having another injector replaced, so I did all six.
Well, just got a call from the shop. The car is back together, and running better than ever.
So in summary...HPFP failed and took out one or more of the injectors. The only wasted money was when I replaced the coils (the plugs were due anyways).
Total Parts ~$2000
Total Labor ~$1000
I pray this is the end of this saga.
That's wonderful. I hope this is all behind you.
Another update - positive!
The shop tested the injectors, and three were leaking pretty bad and the remaining three were marginal. I'm glad I made the choice to go ahead with all 6.
Car is running great so far! I have all the failed parts in my possession, and hope to dig into them sometime this winter when I have more time.
The shop tested the injectors, and three were leaking pretty bad and the remaining three were marginal. I'm glad I made the choice to go ahead with all 6.
Car is running great so far! I have all the failed parts in my possession, and hope to dig into them sometime this winter when I have more time.
Originally Posted By: DriveHard
Another update - positive!
The shop tested the injectors, and three were leaking pretty bad and the remaining three were marginal. I'm glad I made the choice to go ahead with all 6.
Car is running great so far! I have all the failed parts in my possession, and hope to dig into them sometime this winter when I have more time.
When you dissect the injectors and HPFP, post some pics. I'm curious to see what's inside of them.
Another update - positive!
The shop tested the injectors, and three were leaking pretty bad and the remaining three were marginal. I'm glad I made the choice to go ahead with all 6.
Car is running great so far! I have all the failed parts in my possession, and hope to dig into them sometime this winter when I have more time.
When you dissect the injectors and HPFP, post some pics. I'm curious to see what's inside of them.
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Originally Posted By: nthach
Originally Posted By: DriveHard
Another update - positive!
The shop tested the injectors, and three were leaking pretty bad and the remaining three were marginal. I'm glad I made the choice to go ahead with all 6.
Car is running great so far! I have all the failed parts in my possession, and hope to dig into them sometime this winter when I have more time.
When you dissect the injectors and HPFP, post some pics. I'm curious to see what's inside of them.
Same here!
Originally Posted By: DriveHard
Another update - positive!
The shop tested the injectors, and three were leaking pretty bad and the remaining three were marginal. I'm glad I made the choice to go ahead with all 6.
Car is running great so far! I have all the failed parts in my possession, and hope to dig into them sometime this winter when I have more time.
When you dissect the injectors and HPFP, post some pics. I'm curious to see what's inside of them.
Same here!
Originally Posted By: DriveHard
Another update - positive! The shop tested the injectors, and three were leaking pretty bad and the remaining three were marginal. I'm glad I made the choice to go ahead with all 6. Car is running great so far! I have all the failed parts in my possession, and hope to dig into them sometime this winter when I have more time.
Good to read you got it sorted!
Another update - positive! The shop tested the injectors, and three were leaking pretty bad and the remaining three were marginal. I'm glad I made the choice to go ahead with all 6. Car is running great so far! I have all the failed parts in my possession, and hope to dig into them sometime this winter when I have more time.
Good to read you got it sorted!
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