400E idle problem - PeachParts Mercedes-Benz Forum

janos_z · #1 10-13-2003, 10:18 AM

Took my 400E to Canada last week (10 hours each way), and it was fine all the way there, as well as for the first couple days while driving around town. Then one day I pulled into a McDonald's, and when I tried restarting the engine 5 minutes later, the car kept stalling out. It turned over okay, and ran fine if I kept my foot on the gas, but if I let it idle it immediately dropped to 300-400rpms and then just died. It was like that for a couple days (sometimes if I was really careful in letting off the gas, the rpms would stay at like 400-500 and the engine wouldn't die), and eventually the "ASR" light came on too and the car started shifting weird (holding lower gears longer before upshifting). On the way back to the US, I stopped for more gas, and when I restarted the engine, everything was back to normal....

Now the car's okay, but I'm concerned this episode may repeat -- it makes the car pretty much undriveable. But I'm also reluctant to take it to a mechanic since there's no actualy problem with it right now. What could have caused this, and why did my "ASR" light come on? An obvious guess is the idle control valve, but then how come the car fixed itself (for now)? Are there any relays or other electrical pieces that can cause this to happen? Thanks, guys...

joe p · #2 10-13-2003, 11:58 AM

Sounds like it lost a switch and went into limp. Either the EA, EGAS or the switch on the gas pedal. Other likely culprit, wiring harness.

Joe

janos_z · #3 10-13-2003, 10:06 PM

What's EA and EGAS?

Also, I know that some Benz engines in the early to mid 90s had bad wiring harnesses. Is the 400E's V-8 included in this group?

Thanks again.

#4 10-14-2003, 07:56 AM

I allways go for the easy fix, is there any way you could have gotten bad/watered gas up there in knuckland? excessively high humidity while you were there? Put a can of heet in.

TimFreeh · #5 10-14-2003, 08:16 AM

The 400E M119 engine was one of the engines that is effected by the bad wiring harness problem. Your symptoms are classic signs of a bad harness. I would have the harness checked - I'm also pretty sure a batch of bad gas would not cause the ASR light to illuminate.

Tim

joe p · #6 10-14-2003, 08:34 AM

EA = electronic acuator, or throttle body.

E-GAS = the CC, ISC, EA control unit. (the brains of the outfit)

The lack of idle control, "disconnected" feeling of the gas pedal and such are the result of the system turning itself off due to a fault. These are not that smart so odds are the stored code would be due to the result not the actual failure.

The wiring harness will fail and kill the CAN (controller area network) which is the communication link between the 3 main engine control modules. (egas, HFM/LH and DM) This causes the system to fall into limp home mode. (the result of the failure) There will be a few codes in the various module which should give you a few leads however, getting it to fail for the tech is always helpfull.

Joe

janos_z · #7 10-14-2003, 01:47 PM

thanks so much for the clarification -- this forum is great! i hope it was just bad gasoline, but i'd have expected the idle to be inconsistent/rough if there was water in the tank. instead, the engine ran nice and smoothly, as long as i kept the RPMs up with my foot on the gas pedal. so i guess i'll get the wiring harness checked out and ask my mechanic about the other components you guys mentioned.

by the way, the ASR light didn't light up until day 2 -- does this have any significance?

another related question: since i've had the car (about 6 months now), it always has done the following: i turn the key, engine starts, rpm goes up, then dips to like 300-400, then settles in at 500-700. no shudder, no rough idling, but for a split second it always feels like the car will stall out (though it never does). do other people's 400Es do this, too?

i should add that this is different from what happened in canada -- there, the car wouldn't start at all unless i had my foot on the gas as i was cranking the engine, and i had to keep my foot lightly on the gas pedal to keep the rpms in the 700 range at "idle".

thanks again!

-janos

zeronero · #8 10-15-2003, 01:33 AM

Everytime I start my car when I start to move and am still in first gear it will it will stall if I let off the gas. As soon as it shifts into second and then I let off the gas it doesn't. Then in first again it will run fine, it's only after a start it and go in first that it stalls.

Bzoo · #9 11-01-2003, 11:44 AM

Temp sensor?

kanio · #10 07-07-2007, 12:46 AM

my 92 400e is doing the exact same thing as janos_z. i am in hot hot las vegas now, so i need to know if i can make it to albuquerque. any help on this? will i able to make it?

Bzoo · #11 07-07-2007, 07:34 AM

Have this car. Had this problem, Drove me crazy for a year. Remembered the same issue with my Lincoln. I cleaned the idle bleed port with carb cleaner...really cleaned it...easy to do. Take the intake assembly off...take out the screen covering the intake throat and use the extendor tube that comes with the cleaner. Spray directly into the port above the butterfly. Worked perfectly. Never had a problem since. Might not be your problem but it is an easy place to start.
Brian