aarkaah

All,

Having an issue and would appreciate help. Dealer has had the car 1 week.

Issue:
Started a week ago on Friday. Car has rough idle and bucks/shakes at light. Got progressively worse. By Sunday, although cranking car would try to start for about 2-3 seconds - (always started in the end). By Monday, the idle/shakes and bucking were helluva noticeable - I was getting quesy! Drove it to MB dealer and dropped it off. Car drives fine, pulls strong though. No Lights were on.

Dealer:
Tuesday: Diagnosed with faulty x2 injectors, one wire and bad Mass Air Flow Unit. Cost approx $1,200. Oh btw... your check engine light is on!
Wednesday: Parts not in.
Thursday: Parts installed (injectors, wires, MAF) - Still bucking/shaking. More diagnosis needed.
Friday: Re-diagnosed - Faulty Electronic Control Module (ECM). Service Advisor says tech run fault tests on it and confirmed the new injectors were also not acting as they should if they received ECM commands. Must order ECM - cost in neighborhood of $2,000.

Dealer has stated that I will not get charged for any mis-diagnosis or parts - they even worked to apply a "customer discount" - but I have no idea where this is going - and I plan on visiting the service manager first thing tomorrow morning.

Q: Has anyone experienced this issue before?
Q: Should I be skeptical of mis-diagnosis?
Q: How often does the ECM go bad?


Car is a 2000 E55 AMG with 140K miles... running perfectly up until this last week. I have had the car for over 6 yrs and over 90K miles.

Regards,

Double-A

HELP: Dealer can't diagnose - Bad Idle/Bucking at Light

croweld

my 2000 E55 with 130,000+ miles is running perfectly.

however, I have once or twice in the last 6 months experienced exaclty what you are saying. My friend (it's awesome to have a true "friend" that is a MBZ specialist) tells me to reset the computer so it will relearn my driving patterns. Our cars have continuously improving engines, god I love modern engineering. So anyway, that fixed the issues and the car runs fine. I hate dealerships and try to avoid them like the plague. Good luck and if you are anywhere near NJ, I can recommend the most honest automotive technician in the world.

-D

aarkaah

All,

I can't believe the response is so low to this issue. My car is still at the dealership +2 weeks now.

New ECM installed and it run worse than before. I need some suggestions here guys.

slowsky

ive had some of the same issues with no CEL or stored codes...

*110k miles, best 1/4 time while having these issues were 13.2, no issue with power.
*each item i replaced, the idle got better, although i still have some minor shivers here and there.
*no mechanic (indys or multiple dealerships) could figure out what was going on and kept trying to throw parts at it.

here were my steps to smooth out idle/bucking issue:

*o2 sensors: they were getting lazy, helped some
*crank position sensor: fixed hard starting issue, helped tremendously
*maf sensor: helped some
*spark plugs and wires: didn't do much
*fuel injectors: pulled off fuel rail and made sure fuel pump was working properly and also made sure fuel injector spray patterns were good, didn't do anything
*fuel filter: long overdue, helped with the slight bucking issue


you might want to do a compression test too...
also check your cats, they maybe clogging...
can you see the engine shivering?

desired_speeds

That's pretty much my problem. it would randomly misfire, no CELs. I hooked it up to star and valves show that cylinders 4,5,7,8 are firing out of range. I've done plugs and wires, tried another MAF and tried fuel injector cleaner. No difference. I'm sorta lost too.

desired_speeds

btw.. do any of you guys notice a difference when the car is really low on gas? I didn't seem to notice that mine was misfiring during the short time I was driving around with the gas light on.

slowsky

you mean it idles rougher? occasionally it happens...wonder if its the fuel pump then?

mechanic plugged star to my car and we watched the adaptation values live...nothing out of the ordinary...really just feels like an old school muscle car but softer....

one of the mechanics at the dealership said that most of our years 55 engines have some shivering due to the cam profile and due to age people are starting to notice more....said that the 63 engines has a loping idle but most can't feel it due to the vast amounts of insulation and heavy duty mounts to dampen the effects...

desired_speeds

I mean it idles smoother when the tank is empty. I also watched the adaptation values. I noticed the misfire when I repeatedly rev it to 3000rpm and let the idle drop back down. The value is actually out of range with cylinder 4 being the most frequent and 5, 7, 8 being less frequent. Mine at idle can rev up and down and its most noticable when in neutral or park with emphasis on morning start ups during warmup.

I also got the same story about the 63 engines having the lopy idle. But I still feel that my 55 idles too lumpy to be considered normal.

JamE55

Just a guess but could it be the fuel you are using or maybe needs a fuel sensor?

tsquare

JamE55 - Where is the fuel sensor located on the car?

nicobaires

Ignition coils?

slowsky

coils usually throws a CEL if it is out of tolerance...possibly it is out of tolerance but not enough to trigger CEL?

Our cars do run really hot, i'm suprised we dont have more issues with the amount of plastic around the engine bay..

MBFLO

I had posted something of this nature back when i first started noticing it with my E55 ..
I had recieved about the same responses as in this thread .. I never fixed it as it doesnt happen everyday or on rare occasions .. But never while im driving or accelerating , only and i mean only when i pull up to a stop light while my car is in gear and then i put in neutral give it some gas and it seems to clear and not come back within the same day so i never really got in too much deeper about it .
But i recall Peter02AMG posted that he had similar issue after he had SC his E55 and tried out almost everything that you guys have done and IIRC he stated it was his EGR valve.. Not sure if it would have any connection to this but it will be the first thing i have looked at and possibly replaced <if needed> when i take my car in for service next time ..

snooozie

Trying unhook the battery cable and llet it sit for 5 minutes and reconnect. Sometimes it's the computer that got thrown of whatever the reason. This might just solve your problem. Modern technology at its finest

desired_speeds

So egr huh? I've already gotten an extra egr to clean up and put in. I've already been told to check it out as it can cause misfire. I just haven't gotten a chance to put it in. I'll try to do it this weekend.

desired_speeds

I replaced my EGR and cleaned the pipe today. I also cleaned the injector's electrical connectors, and the throttle body. Same **** unfortunately.

Schweinhund

Idle + bucking sounds like a classic MAF issue. But if he changed it. Hmmm. I would change it once more just to be sure.

TPS should throw a code.

Maybe a bad knock sensor?

MBFLO

Damn that sucks was hoping it would fixit

aarkaah

Desired_speeds, looks like we are having similar issues. Keep us updated ...

For my part, the dealer has been working on the issue and thought it resolved... It wasn't. So far they have...

1. Suspected the MAF, replaced (no fix) and then removed it.
2. Suspected the ECM, ordered/waited replaced x2 (no fix, thought the initial replacement was faulty) and then removed it. (note was that it run worse).
3. Suspected injectors and seals... replaced some and wiring. No Fix.

They have reversed the charges for items 1 & 2 as initially discussed. 3 didn't fix the issue either - so they are continuing to diagnose.

Just went down to test drive and car still shudders at light when idling. 1/2 tank of gas. No shudder with AC on. Shudders in Drive (idle) and Park. Drives strong on interstate though.

Anyway 3+ weeks now at dealer. Jesus...



Anyway got the call from dealership that car was ready on last Friday. I just got back from dealer and - YEP - No car.

Schweinhund

Sounds like a vacuum leak. Has the dealer checked for vacuum leaks with a leak detection fluid?

The rough idle, but smooth off-idle and full power are tell-tale vacuum leaks indicators.

Maybe pull the car and take it to a good independent.

aarkaah

I would, but they insisted I pay for parts at very least to release the car. Also, not sure about a good indie in this area and I am travelling in 1 day.

Schweinhund

Have they sprayed it for vacuum leaks?

slowsky

what about coil packs? at +100k miles, maybe its time?

desired_speeds

ive swapped the coil packs around on mine and the misfires stay at the same cylinders

nicobaires

This sucks guys!
I had a stumbling idle and hesitation at low rpms but a new MAF fixed mine.

Hope you find an answer soon