E420 1994 limp mode at 55mph and above !?!?

[kafklatsch]

Background: Plastic guide rails caused lose of timing chain. Replaced engine. I was able to wrestle an 1994 e420 engine away from a guy who wrecked the car in 2000 with 42,000 miles. His plan was to eventually repair the wreck. you know the story, 1 year turned into 10 years and he never got around to it. he maintained the engine running with periodic oil changes. It runs like a dream and was spotless (brings back memories of when i opened the hood on my E420 15 years ago. ). His engine number was within 200 of my own and I have verified all critical parts cables harnesses and modules to be indentical (EPC Startek data)

The engine was installed and ran perfectly, after about 75 miles I took it to 80mph and the ASR triangle lit on the dash. Thats how it all started. The engine ran perfect below 80mph for a short time, but now the light comes on at 55mph.

If I let off the gas, the triangle light goes off and all seems good if I stay below 55.....the rpms shows about 2500+/- and if I down shift, the rpms shoot up to 3200+/-, BUT the speed is still limited to 55 before light comes on - no matter which rpm (gear) - any hints there?

The car now surges at idle. It jumps between 530 and 650rpms. however, It does not shut off. I have a MT2500 scanner and got several codes when i first replaced the engine. I cleared all codes and started with a clean slate. A code 24 & 25 on the LH-SFI module (short in the camshaft circuit) led me to replace the module after verifiying the wiring and camshaft coil ohms. The module no longer shows camshaft circuit errors.

I do see an error DTC 14 (S29/3 idle position switch?) - on the EA module, but it is intermittent. where is it located? could this cause both the idle problem AND asr light at speed?

No other codes have reappeared as far as the MT2500 shows.

I have replaced the following (with dwindling funding);
MAS (bosch reman)
LH-SFI MODULE (used)
Crank sensor
Camshaft sensor.

the crank sensor appears to be the only part that changes engine characteristics.... thus I wasted money on the others.

I reset the Throttle from instruction here. The humming never stopped, but the mechanical sounds did. I read ALL sounds should stop, does this include the humming - should it stop also?

the car idles roughly, but is very smooth when on the gas. The triangle lights above 55, but goes off when i let off the pedal.

I am using the replacement motor's engine harness as it was in spectacular condition, Although, my original harness has never suffered the breakdown commom to the MB's of that time. the p/n's are the same (EPC)


The car ran very good until the timing chain broke. no issues at all.

OF NOTE: when I went to adjust the throttle cable after the engine install, I noticed that part of my kickdown switch is missing. The gas pedal cannot reach the remaing switch part. I swear I remember it being like that for years with no problem. ??? I will replace it this week


Please..... any helpful suggestions are welcome.... I am stuck.