400e ASR limp mode on cold start up

[88260e]

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???

[emerydc8]

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.

[88260e]

YES COLD AND WET!!

[emerydc8]

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.

[mbdoc]

Overcharging or lack of charging can cause that as well.

[88260e]

Overcharging, Lack of charging?? Voltage ?

[anziani]

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

[anziani]

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

[88260e]

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

[mbdoc]

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

[88260e]

should I start looking at the EZL?

[88260e]

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

[mbdoc]

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.

[88260e]

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

[cmcdonnell]

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?