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Drivability question

'95 C220, 205,000 miles.

About a month ago I went to pass another car on the highway, and the engine bogged down and began shaking. When I let up on the throttle, the engine returned to normal. When I would accelerate beyond 2/3 throttle, the shaling and bucking would return. When I turned off the engine and started again, the problem disappeared until I needed to press the throttle more than 2/3.

Having gone through many posts here, my guess is that I need a fuel pump relay. I know I need a wiring harness, but so far the only symptom definitely related to that condition is a CE light which cannot be extinguished.

I also have an SRS light which come on after start and stays on for a minute. From other posts, it appears this is seat belt resistance. If it were the slip rings, it would come on and stay on, correct?

Thanks.

Reply to
LWG
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I would suspect the air flow meter. Do a test on the device.

Reply to
Tiger

You stated that the check engine light is on - have you had someone read the diagnostic codes?

Reply to
Josh

I had the car scanned after the CE light came on, but before this particular problem. The tech said that it was throwing a lot of codes because it is in need of a wiring harness. The CE light has been on for about a year, but the car started and ran perfectly well until recently. I ignored the CE light because I thought it was an artifact of the wiring harness. I have not yet had the car scanned again because I have not yet had the wiring harness replaced, and I thought the results would not be valid.

I have noted that since I have started using a big name brand gas, the problem has been reduced. I still get more than 450 miles from less than 15 gallons.

Reply to
LWG

Thank you. I will keep that in mind. I will likely have the dealership replace the wiring harness, and then see what they say. Is this a defect that would show up on a "loaner" type scan tool?

Reply to
LWG

Where would I find the Mass Airflow Sensor on my C220? I've spent the last few days going through these posts, and I think it is just inboard of the air filter. I think it is easy to replace, according to other posts. Is this right?

Reply to
LWG

That's right about the mass air flow sensor. I am not so sure on wiring harness probability of causing the problem. This is easily checked by inspecting the wires in the engine compartment for any fraying insulation on the wires... all wires that goes to the engine.

Reply to
Tiger

I found the MAF. Silly question: it's held in by two Torx screws, but the pigtail for the sensor block one. I tried to wiggle the pigtail to move it aside, and it won't release or move. I don't want to use force, what's the trick?

Also, in another post I read you can reset the CE light by removing fuse 37, but my fuse box goes up only to 33. I don't have the radio code, and I remember when I put a new battery in it was a little work to get the code and put it in. I'd rather pull a fuse it I could. What am I doing wrong? '95 C220.

I looked at the wires and I can't see anything obviously wrong. I was told I needed a harness by a fairly reputable dealer. I can't see what's wrong, but the dealer wouldn't really work on the CE light until I got the harness replaced.

Reply to
LWG

If you have a rectangular black diagnostic pinout... not sure where on your car, you can push and hold the button to reset all the codes... you also can read the touble code by flashing light. I only know this because of E class of similar year.

You can try searching online for such info.

Since your car is OBD 1... you can simply disconnect the battery for like a minute or so to reset all the codes.

Reply to
Tiger

Another source of wiring harness problem is under your floor mat by the driver seat... pull all the carpet up and you can see a bundle of wires that goes out to the engine compartment... if any of those is frayed by sharp sheetmetal... you can try to repair it with liquid tape... and tape whole harness to protect it further.

Reply to
Tiger

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