Professor Booty

First of all, hi everyone. I haven't been on the forums in a long while. But now something is wrong and I desperately need your help. My check engine light is on. My car is missing really bad. It doesn't start. If I can get it to start it idles under 500 and dies in a couple seconds. If I hold down the gas it will rev up and start sputtering and the rpms drop and go up and then back down and then it dies. Unburned gas shoots out of the exhaust. I don't know if this is related to the misfire problem but there is a whizzing/whining noise (similar to the sound when the car starts or the door is open with the key in the ignition) except not as loud and coming from near the battery. There is also a ticking noise that comes from around the battery as well that you can hear from inside the car. I don't think the battery has anything wrong with it however since all electical things from lights to windows to radio work fine. I really need some help before I start replacing parts that don't need to be replaced. Thanks very much in advance!

NorCal124

have your fuel pump checked out.

ashman

could be the fuel pump or fuel pump relay. if the noise is coming fro behind the battery, the problem may be the ovp as well. check the fuse in the ovp. it is a square unit behind he battery with a plastic lid and a fuse on top. check to see if the fuse is blown.

has your wiring harness been inspected for cracking of the insulation?

AshMan

Professor Booty

My wiring harness was replaced not too long ago. I don't see the OVP. Is it in a different place on the M104? I see a single fuse in front of the battery with a clear plastic clip over it. That fuse is fine. Does W124 have in-tank fuel pump? And where is the fuel pump relay?

ashman

Fuel pump relay could be under the rear seat on the passenger side.

Seems like you are having issues with your car too. mine lost the spark, and my mechanic is having a hell of a time figuring it out. based on testing there is no reason my car should not have a spark...

AshMan

EKL

Your engine light is "On", can you find out what is the error code?

K&C124

Your car has two external pumps located under the car, they look to be located under rear by the tank. The relay is behind the battery, there are two rectangullar relays, the one for the fuel pump is closest to the battery.
"From model year 1990 the fuel pump relay is combined with the a/c compressor module(KLIMA). (MAS) controls: fuel pump, a/c compressor, o2 sensor, secondary air injection, 6,540 rpm limiter." This is from the Bentley owners bible.

After reading more I don't find another place for the relay but did find that your car has an "HFM-SFI" fuel system, hot-film air flow sensor sequential fuel injection system.
All of your cars symptoms sound like what happened to one of my Volvos.
I had to replace the air mass meter thing. It has some kind of platinum wire/film in your case, in the throttlle body intake area with a large electrical connector on it. The diagram show all of this running through the ECM on the MBs. YIKES

Brian Felts

Truly sounds like a timing issue to me. If you are getting unburnt fuel start pulling spark plugs and see what one is soaked. If all of the plugs are very black go back to the timing. Touch base with me on what you find.


Brian

Professor Booty

Ok I checked a few things yesterday. All those fuses and relays you guys said to check are not only fine but immaculate. They all look like they're brand new. I checked the MAF sensor too and it looks perfect. Tomorrow I'll pull my plugs and let you know what they look like. I don't know if I'm not getting enough spark or not enough fuel since when I hold the gas pedal down I can get the engine to rev up a little before it dies. If anyone has any other ideas let me know. I'll see what my plugs look like tomorrow.

YNVDIZW124

Are you saying the LOOK fine or did you actually test them?

Professor Booty

Yeah I tested them lol.

shadowgriffen

have you, by any chance, checked the alternator??? it could have an effect on your dash lights causing the check engine light to come on...also, have you checked your O2 sensors?? its a pretty good idea to check them while your att all this checking.

Professor Booty

Ok I just pulled a couple plugs and this is what they look like. The picture quality isn't that great but you can see they're completely black. I have a feeling all are like this. What does that mean? Should I buy new ones or would they just be ruined again because something else was the cause of this?

kth286

Booty

It is likely to be one of the coils shorted out - be careful it could blow your ECU at big bucks.

Why have you not gotten the codes read pronto.

Regards

ShoreBenz

It may be your ECU that is causing this problem. My car had a similar problem. It began running very rich. Very rich. Cold start was fine, as soon as it warmed up it began to surge, and emit a foul black smoke, blackening the plugs. I changed the HFM, wiring harness, Checked the coolant sensor,OVP, O2 sensor, & throttle actuator, by swapping them with known good parts. The fuel pump was fine, she was getting plenty of fuel. The ECU was sending false codes. A new $1045.00 ECU was installed at the stealer for $900.00 plus labor. Rumor has it that as these cars begin to age, ECU failure is becoming more of an issue. The good news is, if there is any good news; the car is far more responsive than before.

luvmuzik66

Have your fuel pressure checked. you may have a busted fuel pressure regulator and maybe one of the reasons why you are running rich. Or it may be an intake leak. This can also cause the rich mixture because the O2 sensor is getting a lean mix and it's telling the ECU to give more fuel.

Professor Booty

If I buy a new set of plugs will the car run do you think? I might just replace the plugs and drive it to the mechanic and have him figure it out. I could get it towed but if replacing the plugs will work then I'd rather do that. Are Bosch platinums ok for this car? They don't have to be gapped do they?

ShoreBenz

I would'nt use platinum plugs. Why not just clean the ones you have with carb claner for now, though you may want to replace them when the car is repaired. The new plugs will need to be gapped.

Professor Booty

Is air intake cleaner basically the same thing? I don't have carb cleaner.

ebennz

most logical statement yet.

don't sweat the load yourself, let a experienced mb trained tech figure it out, that's what you pay him for.

ShoreBenz

That should work. Then get it to shop. Good luck!

Professor Booty

Well I tried cleaning them with brake parts cleaner and a wire brush and it wouldn't start. Also, is there an easy way to remove the 3 coil packs or whatever they are over the 2, 4, and 6 cylinders? And finally, I identified the buzzing/electrical noise coming from behind the battery. I guess that's the ECU? When I turn the ignition 1 click to the right it will start buzzing over there. I have a feeling that's the main culprit. Well I'm just going to get it towed to the mechanic next week. Thanks for all the help guys.

YNVDIZW124

I had the buzzing noise just when you start the car and it didn't start. On mine it was the fuel pump relay. Get someone to crank it and move whatever is buzzing around to see if there is a bad electrical connection there.

Professor Booty

Well I think I'm going to cry. I just picked my car up from the shop a couple hours ago and it ran like new all the way home. A few minutes ago I got into the car to go out and it wouldn't start. It's making the buzzing and ticking noise from behind the battery again. I eventually can get it to start by pumping the gas and when I put it in D and drive it the rpms will go up and down like I'm flooring it and then slamming on the brakes. No check engine light anymore however. My mechanic replaced the plugs, those 3 coils above the plugs, the plug wires, and the mass air meter. Tomorrow morning I think I'll do what you said, YNVDIZW124, and call my mechanic. I'm so pissed.

csumt76

I would be leaning on that OVP big time, it can cause tons of problems. See if you can find someone with the same car or a spare part and swap them before you go nuts spending more money. I'd say the coils/ air meter were a waste.