I just replaced the wiring harness (which was hard and brittle) on my 93 400E. I started it and it drove flawlessly for 10-15 minutes and then did the same thing as before. It started losing power after that warm up period. The idle was normal at a stop sign, but when I gave it some gas, it barely went, and when I kept the gas pedal down about half way it would suddenly recover power and surge ahead. What is wrong with this damn thing? Is there a way I can troubleshoot it to see if the throttle actuator is bad too? This is my first experience ever with a Mercedes
Benz, and may be my last. This car has only 88,000 miles on it. I have owned this car for a couple of months and it has been great until now. There seem to be some really knowledgeable techs on this site. HELP!!

Garry
400E
735i
635csi

Dont give up on Mercedes just because of this problem,, im sure someone on here will direct you to the problem. Its funny how simple things are sometimes..

I'd guess it's throttle actuator related, when problem happens, you can park the car, remove air filter box, then manually sway the throttle linkage from the point where cable is attached, then inspect the movement of the linkage down to throttle plate, there must be something wrong in that part.

The throttle actuator of M119 can be problematic, when it was extremely cold, my 400E almost killed me when actuator stuck at highway speed twice, I did lubricate throttle linkage periodically as recommended.

__________________
99 BMW 540i 6-speed 110K Km
03 SAAB 9-5 wagon 80K Km
92 400E (Sold) 245K km
Still missing the days with the Benz, it kept me busy.

My 400 had a similar problem and one of the master techs (Stevefb) said it was likely due to a problem with the spark plug wires. In particular he suggested it was the interface between the wire itself and the spark plug. I think he called it a tip. The part itself is replaceable....

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...Tracy

'00 ML320 "Casper"
'92 400E "Stella"

I took the 400E out for another long drive today and it ran perfect and did not exhibit the power loss problem that it still did yesterday (after I had replaced the harness). I hate this intermittent stuff. You can bet it will run fine until I take a interested buyer out in it and then it will act up again. It has done this to me three times now and scared the buyer off each time. I have been all over the top end of this engine and can find nothing. I checked the coolant temp sensor at different temps and the resistance reading is right on. I was thinking of removing the mass flow/throttle body (or whatever Mercedes calls that thing) and inspecting it closely, but I can't see how to get it out of there. Are there any relays I should be looking at? HELP!

Garry

Boy, this sounds like a similiar problem I've been having with my 91 300e with ASR.I' ve replaced the throttle pot and the throttle actuator to no avail.The output of the throttle gradually decreases until the car goes into limp mode . I've made numerous posts on this forum but have gotten few replies. These systems can be a real P.I.T.A. to diagnose. If I could find a true GURU on this system Id be happy to pay for his/her time.I too am ready to give up,but I will keep my car. I've figured out to hook up the throttle manually (deleting the e-gas system) only problem is I lose cruise control.....

How did you dis-able the "e-gas" thing (and what is that). I am about ready to do the same. I can live without the cruise control if I have to. And why is there even a connection between the two? I don't understand how Mercedes does things at all. I am quite capable of troubleshooting and fixing problems if I have a clue of how they are supposed to work. I have been working on my own Bimmers for almost 30 years (even including valve jobs) so I am no dummy, but I don't understand this Benz thing at all!

Perhaps we will both get lucky and find a super tech on this site who can shed some light on these issues. Good luck.

Garry

When Benz added ASR to their cars , they decided to combine the cruise, throttle , and accelerator throttle position into one unit. I believe everything goes through the ASR computer and is out put to the throttle actuator , depending on the data that goes to the computer...accelerator down,throttle opens,wheel slip detected,throttle closes,cruise engaged speed maintained.I'm not sure of your configuration but I was able to remove the control rod between the electric throttle actuator and the throttle plate , adjust it and install it on the accelerator crank arm and throttle plate. This renders the cruise and the throttle portion of ASR inoperative but car otherwise drives normally.
Dan

I sure would appreciate anyone who understands this system helping out. If any one knows of anyone please refer me.I'm willing to pay for their time!Dan

My 400E does not have ASR and the cruise control works fine (although I have not tried it when the car is acting up). I am told this board has some great techs. I hope one of them finds us soon! Thanks.

Garry,
Have you searched on this yet? There have been many, many posts on this issue with a good deal of input from the professional techs. Try a search using a combination of terms, like "asr m119" or some such (since this is usually a problem wiht the M119 engine and mostly with ASR-equipped cars. (I THINK your 400E still has an electronic throttle actuator even if the vehicle doesn't have ASR.)

The common element in virtually every successful 'cure' of these problems comes down to pulling the codes and using that info to track down the source of the problem. In my case, a faulty brake light switch (i.e., on the brake pedal) was enough to cause the system to go into 'limp home' mode. As 994s2c eloquently points out, MB integrated a lot of functions into this system. It's actually pretty elegant when you get to know it (although frustrating when you have the sort of intermittant problems you've been having).

As far as I know, there isn't a single 'magic bullet' type of fix that'll cure your problem. You need more diagnostic info to proceed in a rational manner. I've never actually pulled the codes myself but others on the site have (as you'll see when you do the search). I paid an independent tech for an hour of diagnostic time, which led to the $15 brake switch diagnosis -- money well spent!

__________________
Steve
'93 400E

Go read your other thread. I am not the guru of EA's but, I've never met one either.



Joe

__________________
Project Smoker, '87 603 powered wagon
Hauler, 96 CTD can you say torque?
Toy 73 Cougar xr7 convertible
Acme Automotive Inc.
Raleigh NC
919-881-0364

Bimmerman - just curious but how long/how complex was it to change out the wiring harness?

Also have you ever owned and E31? If so what was your experience with it?

Replacing wiring harness on my 400E took me less than 1 hr, it's very straight forward.

__________________
99 BMW 540i 6-speed 110K Km
03 SAAB 9-5 wagon 80K Km
92 400E (Sold) 245K km
Still missing the days with the Benz, it kept me busy.

EA is the 'electronic accelerator', which is really the throttle actuator--the gizmo that opens and closes to let air into the engine. It is an electronically controlled electric motor coupled to the throttle butterfly shaft. It has a position sensor (variable resistor) for the throttle(accelerator) position, and another variable resistor (position sensor) for the throttle butterfly shaft.

You push on the accelerator--and first a micro switch on the top of the accelerator pedal opens and signals the 'engine control unit' to couple the 'electronic accelerator' motor to the throttle shaft (there is an electromagnetic clutch that disengages at idle or any time the computer says 'tilt'.)

The the EMU/EA checks the position of the throttle position sensor, checks the anti-slip, ESP,ABS systems, and determins if the throttle needs to be opened. If -yes-, then the EA computer sends a series of pulses to the EA motor, which rotates the throttle butterfly open. During this rotation, the EA/EMU checks the actual position of and speed of opening of the throttle butterfly shaft. This continues-always checking first, then opening the butterfly more-until the measured opening agrees with that commanded by the accelerator pedal. The EA/EMU then holds that throttle opening until the accelarator pedal moves (or one of the other systems like engine overspeed, transmission shift computer,transmission torque limiter, ABS,ASR, ESP calls for a reduction in throttle/torque/engine speed.

Fully closed to fully open takes less that 200 milliseconds. Open to closed is faster because the butterfly shaft is spring loaded to close.

The computer system has lots of safety features built in to prevent 'uncommanded throttle opening' that some cars seem to experience. Frankly, I don't see how it would be possible in the MBZ system unless a least 3 systems failed simultaneously--the accelerator pedal switch, the throttle (accelerator) position sensor, and the throttle butterfly shaft position sensor, AND the electromagnetic clutch beteween the throttle motor and the butterfly shaft.

A simple wiring short won't do it because the accelerator position sensor has a known range of values, and changed from (low to high) on pushing down on the pedal. The actual butterfly shaft position sensor has a different range of values, that changes in the opposite direction, so the system would detect the fault as soon as it a hppened and open the electromagnetic clutch.