400e ASR limp mode on cold start up
 

So recently my 1992 400e has been going into limp mode intermittenly on cold start up with ASR light on goes away after restart? Harness is new so pulled the throttle body and sent it to BBA reman in Taunton Ma. They called today and left a message saying it was working fine come pick it up?? It's original so at the least the cable should be bad??? So should I trust there judgement or send it somewhere else??? Or could my problems be something else?? Other symptoms are longgggg cranking and hesitation on acceleration since I've had the car???

I get that problem every year when it gets really cold here (below 32F is really cold for Tucson). It is only intermittent and happens less than a hand full of times per year on start-up.

Like yours, it corrects itself after shutting down and restarting. My ETA has been rebuilt by 4Mercedes and I doubt it is bad. The wiring harness has also been replaced. It seems to happen more often when it has been cold and wet. It's a mystery. If you figure it out, let us know.

By the way, if you do a search for Mercedes ETA on Youtube, you will see a video that shows you how to test the ETA yourself with a digital voltmeter.

YES COLD AND WET!!

Here's a video that shows you how to test your ETA.
Mercedes throttle actuator internals test. M119 motor 1995 SL500 - YouTube

There is a micro-switch on the gas pedal that affects the limp home mode. I have never replaced mine. Maybe I'll give that a shot if it shows up again this year. I already changed the Neutral Safety Switch.

Overcharging or lack of charging can cause that as well.

Overcharging, Lack of charging?? Voltage ?

I have been fighting this problem for 2.5 years. We have tried numerous control units, Throttle actuators, wheel sensors, the little microswitch on the gas pedal and every other thing that has been suggested. The car runs beautifully after a couple of restarts in the first 1/4 mile. I've had retired Mercedes mechanics look at it and come away stumped. I've tried everything that mbdoc has suggested. We have new tires, battery, alternator, etc. Monitored the voltage while driving and start up, everything OK. Have a good harness and wiring to the ETA. Frankly, don't know where to go next!!
Anziani
'93 320CE 208K
'95 E420 129K

A follow up to my own post. I am beginning to think that this might be a relay problem. If you have a relay that pulls in on startup and one of the contacts is bad or dirty or out of tolerance distance wise, that could possibly trigger something. It could be that when cold, the contact resistance changes and it takes a while before this relay has heated up.
While I put in a brand new OVP relay, I may try another just in case. I am also looking at every other relay in the engine compartment.
If any one has an idea, I am all EARS!
It has turned into a battle of "good vs. evil"
Anziani

tried to bench test ETA but the pug on the harness is different so the numbers are not the same??

Vottage issues are common, look for Over-charging when the car is started.

should I start looking at the EZL?

If the lower harness is bad could this cause over charging ? Alternator is only maybe six months old.

First thing is determine whether or not there is a voltage/ charging issue.

Start by charging the battery overnight with a trickle charger, then connect volt meter to the car & then start. watch the volt meter & see if the voltage is correct or not.

Thanks mbdoc, and the rest for all the ideas this weekend Ill be back at it, keep you posted

My 400E is hard to start now that it's cold outside. One thing I notice is the fuel pump only runs for a very short time on cold start. I replaced my upper harness and am tuned up. Then today I got in the car and it started right up!?? Anybody having the fuel pump symptom like mine?

It's hard to imagine how the upper harness could affect the fuel pump operation. When my fuel pumps started to go out, it sounded like there was gravel in them if you stood towards the back of the car while it was idling. It turned out only one was bad but I replaced both.

I put the throttle body back in it ran fine, then I was driving it for the relearn procedure and it died on me as soon as I got a couple miles from the house it died. It was cranking but would not start? Very wet that night maybe something got wet? Maybe it's temp related something got hot? I'm lost on this one, I had it towed home and then it started right up? Now it starts right up and runs fine took it on small drives and seems ok but I'm hezatent to drive it far???

https://sphotos-b.xx.fbcdn.net/hphotos-ash3/68649_10200389774735257_937855203_n.jpg

So I was looking around today and discovered that the wiring that is all damaged does lead to the EZL ! It is the one in the picture bottom right under the number 2
the connection has some numbers on it???? Any help on what it connects to and or if its available or am I screwed ???

maybe knock sensor??

The plug with the #2 on it is an EZL trimmer plug (#274 in the attached diagram). Here's a lengthy discussion on that subject alone. EZL Trimming Plug Guide

If you want to try a used one, check ebay.

It looks like there is a split in part numbers. Up to the end of 1992, it is 013 545 6332. Starting in 1993 it is 014 545 4532. See the attached parts list from the Mercedes epc.

I don't know if your engine wiring harness has been replaced yet, but a bad harness can destroy this module.

It's not the trimmer plug, it's the connection below the trimmer plug in the pic, I think it's the knock sensor

Sorry to Bother You Guys
 

I realize you guys are real technicians concerning these matters. I am no mechanic. Just a soldier away from home with a bad case of the blues because my 1992 300E 4Matic which is 251,000 miles of pure awesome appears to be about to strand me about 200 miles from home in a remote location. I registered on this website and started the previous thread because frankly, I don't know what else to do and thought someone might either tell me I am about to have to finally pay to have the 400E up and running or that there is something I might do to at least get home tomorrow. Any advice or recommendation would be greatly appreciated. Thank you very much, in advance. Sorry to interrupt your discussion. CJTucker

1992 400E 150K
 

I suppose I can jump in with a new issue. Since it appears that I will soon be having a funeral for my 1992 300E 4Matic, I need to start getting over the mourning process and learning more about my 1992 400E that I just purchased for $250. It has 150,000 miles on it; yes, 100,000 less than my 1992 and when the person I bought if from accepted $250 I was more than happy to oblige.

The car needs some serious work, brakes, rotors (in the engine - I will freely admit I do not know what that is but the former owner gave me the CD's with the schematics and instructions), a new radiator, fan, and fan clutch. The car was disabled b/c the fan clutch siezed on the highway sending the fan into the radiator creating a hole in the back of the radiator. There is no oil leakage in the engine (as opposed to my 1992) and the body is in as good a shape as it could be after 21 years. I am told by my German mechanic who took good care of my 1992 that the cost is around $4000 total. Still worth it to me after knowing through direct experience how well the 300E took care of my family and I over the years.

My question, other than the one about how I am going to get home tomorrow with the serious new vibration issue over 65 mph in my '92, is am I crazy to think that it is ok to spend this money on this car. Is it just a fluke that my '92 ran like a tank with just a little coolant and fresh oil for nearly 100,000 more miles through significant temperature / climate change, and through the years without so much as a hiccup every now an then (a new alternator at 230,000 miles, a new exhaust at 210,000, a new serpentine belt at about 200,000)? Seriously, I am almost without the ability to describe the awe that I have towards the 300E, even though it appears it might be ready to die...today.

I humbly ask to join the discussion and get some feedback from you gentlemen, who are obviously aware of the utter beauty of these vehicles. Thank you, in advance for any responses. And, again, I am sorry if I have intruded without invitation. CJTucker

So it looks like the culprit is knock sensor wiring, hopefully I can replace it this week and keep you posted!!