oldguy44

I screwed up and gave my 94 129 to my granddaughter as a throw away first car. She barbequed the engine when a heater hose blew, I found a used engine and put it in. When It started it had a check engine light but it was running fine. I figured that I would get to it eventually, well eventually came when it needed to be smogged. I just pulled the codes and they are as follows ( 38 pin connector ). pin 4 code 4 low or high voltage to MAF. Pin 7 codes 3,5,6,14 Most of which seem to be wiring related. Pin 8 codes 5,6,9,10,11,12,13. All of which seem to be related to voltage supply interrupted. Pin 19 codes 10, 19. 10 is a duplicate of pin 4 code 4 19 is trans upshift delay. It is running extremely fat like 5X allowable out the tail pipe

I am debating about trying to get it passed smog or parking it on the side yard and parting it out. A good share of the codes seem to be related to voltage supply, I am wondering if anyone has seen anything similar.

My next step will be to see what will cancel and what returns that might tell me something.

oldguy44

Update,

Managed to cancel all the codes except pin 4 and19. they would not cancel. Dug into it and found a bad spot in the cable that feeds the throttle body down by the electrical center by the right hood hinge. I carefully cut into the insulation and fixed the wiring, it seems to be going the way of all the under hood wiring of that vintage Mercedes. The code 4 on pin 4 disappeared and the CEL went out. My granddaughter drove it and when it warms up it now has an idle roll which is bad enough to kill the engine at an intersection. If you press down on the accelerator very slightly it smooths out. Is there a base idle adjustment on that thing somewhere that would allow me to open the butterfly slightly and maybe smooth it out?

I also have another throttle body but it appears to be a giant pain to change it and I have no idea if the throttle body is any good.

If anyone has any insight to an idle roll I am open to anything except replacing the wire loom. If that becomes necessary it will get parted out.

FATHERTIME

Check fuel pressure regulator. Pull vacuum hose off and see if there is fuel in it. Also air temp sensor can do that too.

oldguy44

Is the air temp sensor the ones that are in the cold air tubes to the air cleaner near the radiator?

I have no CEL but now the ASR and ABS lights are on and the code on pin 6 is closed throttle recognition signal to ECM and fuel safety shut off to ECM. My presumption would be that the closed throttle signal would come from the electronics on the throttle body, that coupled with the fact that the idle smooths out when you put the slightest pressure on the throttle pedal is sounding to me like throttle body. However experience has taught me that logic and Mercedes wiring are mutually exclusive.

Whatever light it may throw on it, the idle roll started with repairing the wiring to the MAF, I mistakenly stated that I repaired the wiring to the throttle body, but it was the repair on the cable that goes to the MAF that cancelled the code 4 pin 4.

Kebowers47

Unfortunately, the car has all the defective wiring harnesses and it all must be replaced. The insulation on it all will turn to dust and short,ground out, etc. Transmission upshift delay due to delay in upshift on cold start to warm catalysts up faster. You will have to rebuild the harness to the Mass flow units and the electronic throttles and then all the other engine compartment harnesses and intentionally everything inside the body and everywhere on the chassis.

oldguy44

Just for the sake of argument I am going to change the throttle body because I have another one. If that provides a temporary fix great if not the car will wind up on the side yard to be parted out. There is no way I am going to rewire a car that has passed my ex wife on the all time hate list. I gave it to my granddaughter as a throw away first car. Perhaps if I can temporarily repair the thing I will have time to find a replacement car and throw it away. I do thank everyone for confirming what I had already concluded that it has become a large boat anchor.

Kebowers47

It IS Unfortunate but is what it is. It is a shame to part out a good R-129---but many others have made that decision. If you have the time, it is way more profitable to part it out than try to sell it as-is. If it needs a lot of other work to bring it back--part it. I am in a similar situation with a 1994 sl-600 with the wiring to do. Done the mass flow looms, the electronic throttles, hydraulic cylinders on the top and most other 'defects. Still have to do the A/C evaporator and driver seat and re-spray the white paint.I have new A/C comp,drier,etc. Have done the dash display and vacuum system complete. I rebuilt the transmission just before I put it up for restoration I have already rebuilt all the BOSE speakers and amplifiers. Buying this car was a big mistake---it had been wrecked on right front and slapped back together so it looked good, but wasn't.

oldguy44

If there is something that qualifies as a GOOD R129 this one does not. I bought it in a basket with the intention of doing an engine/ trans transplant only to find out that the transplant would have required really major surgery. I found enough parts on the internet to put it back together. The very first thing I did was to rebuild the engine loom, a hundred dollars worth of wire and a week I built a new loom. plugged it in and it started right up. The engine ran like krap so I pulled it out and did rings and valves. It actually served as my daily driver for around 8 years with constant electrical problems which I was able to keep up with. I did redo the trans about 5 years in and kept it going. I got too old to climb up and out of it so found a '63 Pontiac convertible that became my daily driver. I kept the Mercedes around to drive in between projects on the Pontiac and when I got the Indian to a reliable stage I parked the Mercedes. Was going to sell it only to find out that it was totally worthless. I could actually get more money for it at pic a part than on the retail market.
The thing that irritates me the most about this thing is that for a supposedly magnificently engineered vehicle it is a royal PITA. wiring that deteriorates, constant attention required to keep the top working, overly complex electronics etc.......... My Pontiac and every other old car I have ever owned did not have disintegrating wire or any of the other problems associated with this car. The top hydraulics on the Pontiac are the original and it is 30 years older. Top goes up and down without fail. I have to say that I am not very impressed with Mercedes and can take a torch to it and part it out without shedding a tear.