93 300e 2.8 throttle body replaced and still runs awful
 

I just replaced my throttle body with a rebuilt unit and the car still surges and idles up and down and shuts off. I did research many psotings here about the issue but I am at a standstill. I have no check engine light or other lights on and i pulled the readings with my tester.
Socket 14. 2 , 11, 5, 2
I highly doubt its the opv or the stop light switch. If anyone can help me out on what else to look for. I changed the plugs and wires 2 months ago as well. How can you tell if wire harness has been replaced? I also replaced edu unit a few years ago and cleaned the maf sensor

shut eng off disconnect mass sensor connector , then restart , and HFM control unit will revert to 50 % position see if then stalling and surging goes away

X2...MAF

Visual inspection on the wire harness, look for cracked insulation particularly around the harness area going to the coils. Don't forget the lower harness going to the alternator.

Good luck!!!

OVP relay can be a problem so try swaping one out for another to fit your car .First owner of my car had this trouble and even went and had the head rebuilt .Fitted it all back to find problem was still there . And it was sorted out after auto shop changed the OVP relay

On the ovp relay...i read somewhere that the abs light would stay on if ovp relay was bad? Or is it possible to test it? Would the egas module under the dash in passenger side play a role if the thottle body was not good and can possibly fry the egas module?

Cleaned the maf sensor and then disconnected it. At park position it still idles up and down at about 1000rpm and when i put at the drive position it runs better and no surging but almost stalled on me ...about to turn off. This all with maf disconnected

Try lightly rapping on the MAF, if it changes then the MAF is bad. OVP as mentioned is another likely culprit, unfortunately I don't know of a definitive method of testing one other than replacement.

Good luck !!!

Is there a date stamp anywhere on the harness?

Yes toward where it connects to the ECU??? near the battery. It is on a white tag. The ones I've seen say Delphi on them.

Ok i found it.....1993 on mine

I took a good look at the harness and it looks ok...I do not see any visible cracks on insulation tubing or the black tape or threaded tape. I cut open the maf line tubing to inspect the lines inside and they look good. Tubing on the line goi g to alternator is craacked open ...but the lines inside look very good

Surprising for a '93 dated harness but it sounds like a win. When my '93 was bad it was blatantly obvious, the degradation was severe.

The car was garaged for many years before I purchased it and owned by a mercedes tech's wife who only drove to work and back. I guess not exposed to the elements.

check OVP relay date code