M119 still won't run when hot.

[Gmach]

Has anybody found the smoking gun for this fairly common problem.... if you read all the forums?
I have changed just about every conceivable part in the ignition system with no long term luck.
I change a part and it sems to be OK for a little while then it starts again...fist the slight hesitation or miss when pulling away from a light that just get worse and worse to the point the car wants to stall.
Let it cool down and it runs just fine...for about 15 minutes...then it starts again.
Replaced crank and cam sensors, MAF, dist. caps, rotors, backing plate with 'o' ring, plugs, ign module, LH module, wires, fuel pump / filter.....all with no fix.
This has been described numerous times online with dozens experiencing this phenomena but no one has posted what they discovered, if anything. Have you had this issue with your M119 engine?
Did you spent hundreds on parts with no solution?
Did you accidentally find a bad ground or switch or broken wire that solved the problem?
Share your findings....I'm about to jump off a bridge!!!
There has to be a common fault here with all these cars....what is it?

[gerryvz]

Have the diagnostic geniuses in the W124 forum at Banzworld been able to help identify the issue?

Upper and lower wiring harnesses changed?

Have you cleared codes, run the car, and seen what codes come back? Codes for the various systems should point you in the right direction. Throwing parts at it probably isn't the best way to do it, unless you have spares for all of them.

Perhaps it could be a fuel issue, rather than an ignition problem.

[gsxr]

Replaced crank and cam sensors, MAF, dist. caps, rotors, backing plate with 'o' ring, plugs, ign module, LH module, wires, fuel pump / filter.....all with no fix.
This has been described numerous times online with dozens experiencing this phenomena but no one has posted what they discovered, if anything. Have you had this issue with your M119 engine?

Have all of the above parts been new (not used), and OE/OEM items (no URO/APA/FEQ/etc)? You are rapidly running out of items to replace. There's a possibility that one of the new items is defective, but if so, it will be a difficult process to identify it.

Have you cleared codes, run the car, and seen what codes come back? Codes for the various systems should point you in the right direction. Throwing parts at it probably isn't the best way to do it, unless you have spares for all of them.

+1 on pulling codes. If there are zero codes from any system, that sort of points towards secondary ignition system or fuel, and if it's a misfire I'd lean towards ignition stuff. At this point you also need to view live data to check readings from various sensors in case anything is way out.

[gerryvz]

First of all, any other diagnostics is a mute point, unless the upper (and preferably lower) wiring harness has been replaced with a known-good harness with non-eco-junk wiring.

[gsxr]

Good point - I was assuming the harnesses were already replaced, but that's another item to verify.

[Stevester 500E]

Have you checked or replaced the fuel pressure regulator?

[gsxr]

Have you checked or replaced the fuel pressure regulator?

Good point, FPR should be on the list as well (cheap insurance at <$50 for Bosch). Fuel pressure can be ruled out by connecting a fuel pressure gauge that can be viewed while driving; if fuel pressure remains in spec during the misfire / lack of power, the problem is not with fuel supply to the rail.

[Gmach]

All the parts were good use parts from a donor car that was running. The upper harness was replaced long before this all started but not the lower. Point of interest ....when I replaced the engine mounts one of the knock sensors was damaged, which I repaired, could that be a culprit?

[Gmach]

Fuel pressure is good as is the pressure regulator. I'm thinking it's a bad ground or something like that. Something that has he potential for failure in all these cars because the symptoms are repeated so many times by so many different owners.

[Gmach]

I did notice that when I replaced the coils it did seem to be a longer time period before it started to miss...and when it did I could get control back of the RPM if I very slowly applied the accelerator. It didn't like it if I applied too much throttle too fast. This is a non-ASR car.

[Gmach]

Do you have a part number for that lower harness?

[Stevester 500E]

Does the car run long enough for a half hour drive?
As stated on this thread, you should pull the codes.
Get an inexpensive blinker and breakout box on ebay.

Drive the car a couple of days. Pull codes. Report back and I am sure people hear will try and point you in the right direction.

I know, it's frustrating. Sometimes taking a breather is all it takes to calmly regroup.

Fuel pressure is good as is the pressure regulator. I'm thinking it's a bad ground or something like that. Something that has he potential for failure in all these cars because the symptoms are repeated so many times by so many different owners.

[gerryvz]

Do you have a part number for that lower harness?

The 400E lower harness is no longer available from MB.


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[Gmach]

Does the car run long enough for a half hour drive?
As stated on this thread, you should pull the codes.
Get an inexpensive blinker and breakout box on ebay.

Drive the car a couple of days. Pull codes. Report back and I am sure people hear will try and point you in the right direction.

I know, it's frustrating. Sometimes taking a breather is all it takes to calmly regroup.

I have been reading the codes and there is never anything definitive. The last time I read them, yesterday, I only got one on socket 7 #6....starter lock out/backup lamp switch.
I have replaced that last year....surprised it reappeared....but would it cause the sorta issue with running rough and stalling when hot?

[Gmach]

The 400E lower harness is no longer available from MB.


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Could a suspect lower harness create the poor running when hot?
Is it re-buildable?

[gsxr]

All the parts were good use parts from a donor car that was running. The upper harness was replaced long before this all started but not the lower.

Uh-oh. Transferring used parts can often be useful for troubleshooting... but in this case, I think it is VERY likely you may have transferred over an item which isn't 100%. Can you list out every item swapped and if each is brand new or used from the parts car?

Point of interest ....when I replaced the engine mounts one of the knock sensors was damaged, which I repaired, could that be a culprit?

Faintly possible, but unlikely. It would not cause a misfire, but could cause a lack of power. However, this should trigger a consistent code on the EZL.

Could a suspect lower harness create the poor running when hot?

No. Or at least VERY, very unlikely. The lower harness is for the starter, alternator, and oil pressure/level sending units. Nothing to do with engine management.

Is it re-buildable?

Yes, and Jono rebuilds them. At the moment he's the only source for 400E lower harnesses other than a DIY attempt, which I wouldn't recommend unless you have access to the appropriate high-temp wire.

[Stevester 500E]

I personally have this code on my car, and my car is running fairly good, just a smog issue with my car.

I have been reading the codes and there is never anything definitive. The last time I read them, yesterday, I only got one on socket 7 #6....starter lock out/backup lamp switch.
I have replaced that last year....surprised it reappeared....but would it cause the sorta issue with running rough and stalling when hot?

[gerryvz]

These (neutral safety switches) can go out quickly, even new ones. I went through three of them in about 5 years on my former E320 wagon. And, there is a calibration process that must be followed for these when a new one is installed. Not saying this is your problem.

I am not sure that a lot of folks on this forum have had the same issue that you are experiencing. If someone did, it would be documented here along with a solution. There is no better or more complete forum on the Internet for troubleshooting M119 engines, at least the LH-injected version.

I'm still not convinced this is an ignition problem. BUT, have you looked at EZL and the two coils, speaking of ignition? If I had to guess, I would say a bad coil is your problem. EZL will usually either run the car, or not (or just one cylinder bank).

Look for threads here on bad coils.

Also .... E-GAS (if you have ASR; T/LLR unit if not) and ETA?

ETAs have the same eco-junk wiring that the upper and lower harnesses do (inside the ETA as well as the cable) plus other internal contact components and gears that wear out.

[Stevester 500E]

Check all vacuum lines, check the vacuum line and elbow that connects to the ezl.
When did the poor running begin, all of a sudden?

Check all spark plug wire connections. Pull them out and reseat them on both the caps and at the spark plugs.
Check to make sure there is no binding up at the throttle linkages.

You might want to pull and plug back in every place the upper wiring connect to; injectors, ground, cam shaft sensors, etc. Un-plug the connector and check the pins to make sure they aren't dirty or bent.

Make a rig to let you check fuel pressure while you are driving and see if you are maintaining fuel pressure at all times.

[gsxr]

I'm still not convinced this is an ignition problem. BUT, have you looked at EZL and the two coils, speaking of ignition? If I had to guess, I would say a bad coil is your problem. EZL will usually either run the car, or not (or just one cylinder bank).

Look for threads here on bad coils.

Gerry, according to his post #'s 87 and 90 at this thread, both coils were replaced... but possibly with used parts as noted previously:

https://www.500eboard.com/forums/showthread.php?t=7506

This temporarily fixed the problem.

[gerryvz]

Coils can go bad when they get heated up, and replacing with used coils is never a good idea except for temporary testing purposes. It's best to replace both coils at the same time with new units, and they are not hellaciously expensive (particularly if sourced at places like Amazon or AutohauZ).

If/when replacing an EZL, it's HIGHLY recommended to replace the coils with new ones so as to eliminate any damage that bunk coils could cause to the EZL, potentially burning it out (again).

[Modpryor]

I have the perfect solution for your problem my car was in the shop for several weeks. If your
lucky it's one in expensive part.

Check your mass air flow sensor
I'm almost sure that's your problem.

Good Luck
Courtney Pryor
Mercedes Sales Consultant


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[gerryvz]

It appears that the geniuses at Banzworld's 124 forum, particularly my pal Q*baert, have armchair-diagnosed your problem.

Appears that there is some Russian Roulette going on with used parts. Have to use proven, known-good used parts or the whole operation is a moot point. Or new parts.

Since this situation is clearly now under control at Banzworld, I'm going to close this thread. If it's one thing I can't stand, it's copied-and-pasted threads posted here and to other forums.