1994 E320 W124 Wagon High Idle - PeachParts Mercedes-Benz Forum

kwontumspeed · #1 12-17-2010, 07:34 PM

Yes, another one of these threads...

With all the searching I've done to troubleshoot this(thanks for all the advise I was able to find), I have a handful of final questions. But before I ask, this is the back story.

1994 E320 W124 Wagon Non-ASR:
A couple of months ago I started to get an erratic idle, but never lower than spec. It would hover around 800 then jump to 1100 and flutter in between. Sometimes it would not flutter but just remain high. Current state, it hovers at 1100 and up to 1400 - all this in idle(P or N).

The EA in the wagon is a rebuilt unit from a 1995 (I still have the original 1994 that was taken off and replaced by the 1995). I don't know to what extent it was rebuilt except that the pigtail and wires within are new, so the motor and the potentiometer could be OE. When the ignition was turned to the 2nd indent, the EA would make a noise, like a slow churning noise (I can't say how long that has been there, and if it occurred in conjunction with this issue). I assumed it was the motor within the EA and therefore could be the cause to a failing EA - the reason for the high idle.

To help troubleshoot, I installed the original 1994 EA that I had sitting in a box. The thought process here was that the only reason this EA was removed was the cruise was inoperative . There was no high idle. So I was trying to eliminate the high idle from the equation with the 1994 EA. After install, the wagon reacted exactly as it did with the 1995 EA - almost identical in every way. (Maybe adaptation?)

So then I started looking in other areas:
The OVP was replaced.
Battery OK
The kickdown switch was replaced (it would stick)
The air temp sensor and MAF were cleaned
Vacuum lines checked
FP Regulator OK
Harness has been replaced

All codes were cleared, memory cleared.
(Unfortunately, only emission codes were taken with the 1995 EA before removal: Code 6)
1994 EA:
Emission: Code 6 - ISC Faulty
Pin 8: Code 8 - ISC system at upper or lower control stop or CC or EA indicates LHM
Pin 14: Code 2 - EA/CC/ISC control module...

Is this all pointing towards the EA again?
There aren't any MAF codes so I'm assuming that unit is ok?

I'm going to install the 1995 EA and pull those Pin8/14 codes, but the fact that the 1995 EA makes a noise, and the 1994 is dead quiet at 2nd indent makes me weary about that unit anyway. Does anyone have any insight on what the motor does in the EA and what the potentiometer's duty is? Is it possible to determine what is good between the two units and build a hybrid from the two?

Any help would be greatly appreciated!
Robert

mbdoc · #2 12-20-2010, 08:18 AM

Most likely the throttle actuator is still causing that problem.