suginami,

Thanks for the help I will be sleeping at a Holiday Inn Express tonight due to their effect.

Today I did look at my car and did reset the computer. The wiring harness I assume goes into the "black box." It looked fine when I checked it, if that was it.

My idle problem is a bit misleading. The engine idles prefectly, its when I release the gas and the rpm's drop the "trigger" that tells the engine to idle does not kick in until the engine almost dies. Then once is catches it idles fine at 600 to 700 rpm.

 

No, the engine wiring harness goes all over the engine, to the injectors, etc. If you've seen the harness off of the car, it looks like the cross between a mess of spaghetti and a giant octopus.

The harness is pretty thick, and is wrapped in that black fabric tape. A section of mine is attached to the firewall at the back of the engine, and I carefully slit mine with a utility knife to look at the insulation. There are places where you can inspect the wires without cutting the black fabric tape, like at the injectors.

You probably should take it to a Mercedes mechanic to have him inspect it.

 

SOME FEED BACK


GOT NEW OVP RELAY. BEFORE PUTTING IT IN I DECIDE TO START CAR FIRST...........YIP IT STARTED 90% BETTER THAN BEFORE. (MURTHIES LAW) STOPPED IT AND PUT NEW RELAY IN. STARTS THE SAME. SO I AM NOT SURE IF WE SOLVED THE PROBLEM. AT LEAST WITH NEW RELAY IT WILL SOLVE FUTURE PROBLEMS.

PUT VACUUM TO EGR AND CAR RUNS ROUGH. RELEASE IT AND SMOOTHES OUT. CAN HEAR THE VALVE POPPING WHEN VACUUM IS RELEASED. DOES THIS SOUND RIGHT????
WILL CLEAN PIPE AS DESCRIBED SHORTLY.

THANKS

 

If you applied vacuum to the egr valve the car should idle rough.

You still got a code for an inoperative egr valve, so I'm guessing your egr valve is sticking at times. If the valve is stuck in the open position at start-up, it could explain the rough idle.

You should still update it to the new part #.

I'd also suggest having the pipe reamed out or replaced. I'm sure it is somewhat restricted, but not completely, as the vacuum test worked.

 

I have a similar problem with my parents 94 E320.

The car starts up fine when it its cold, left overnight in garage. The car also starts up fine if its only been shut off for say 5-10 minutes.

The problem is when the engine not entirely cold. or not entirely warm. Sometimes it requires many cranks, then the engine would finally start, stumble a bit.. and run as perfect as it could after its started.

however, i checked the OVP and it is already the one with the new part number.

what are the chances of the newer part # OVP failiing? If its not the OVP failure, is there any other way to diagnose the problem. (fuel accumulator, fuel pump relay etc.)

 

I don't think it's your OVP because your car starts.

It's either a fuel supply problem or a spark problem. I don't know which as your problem is unusual.

Do you know if your engine wiring harness has been replaced?

They are all bad from 1993-1995 on the 3.2 liter M104 engine and the 2.8 liter M104 engine.

The insulation on the wires flakes off, causing shorts. It manifests itself in a whole set of weird, random, hard to diagnose problems.

 

I think back in 95 or 96, my parents took the car back in for a recall, i think it was regarding a wire harness.

Was the problematic wire harness under a recall??

 

There is some confusion regarding the wiring harness that you mentioned.

There was a recall for a wiring harness that went under the drivers side floor mat.

There was never a recall on the engine wiring harness. I would take your car to a Mercedes dealer or independent Mercedes shop and have your engine wiring harness inspected. The dealers and shops that specialize in Mercedes have surely done hundreds of them.

 

Thanks for your help suginami, i will take it to a Mercedes specialist.

 

All I can add to this is as Suginami has suggested its probably the wiring harness, I was parts chasing with similiar problems then finally went with the harness(installed myself took about 6-7hrs?) and ALL my troubles went away!......Be aware though they will try to charge you up to $700.00 plus labor, I got mine for $150. with ALOT of arguing and evidence of the "problem" that doesnt exist. Currently Im in contact with the NHSTB board and trying to initiate a recall on these cars, so if your cars turn out to have bad wiring harness PLEASE complain to the board to help solidify my case(there are 16 complaints already) http://www.nhtsa.dot.gov/
Thanks, Chris

 

Re: The wiring harness on the 104 engine. I, too, went through a series of weird/unexplained engine problems before finally ending up at the harnesss. Fortunately I did all the investigating myself and but it got to the point where I wouldn't take the car out if it looked like rain 'cause it would just stop in the lightest rain. In my case I was trying to replace what I thought was a defective coil, but as I swung the spark plug wire up I noticed through a small gap in the black over wire that the white low voltage wire on the inside was bare. The insulation was gone and as I unpeeled the harness wire to re-tape the low voltage wire it's insulation came of in crispy pieces. Totally shot. Mercedes Canada did replace the harness without much arguing (even though the local dealer tech was so surprised.."I've never seen that before"...yeah, right! Anyway, I got the harness for free but only if the dealer installed it. When I ask what the book time was for the job I was not at all surprised to discover that there was NO TIME entered. So watch out 'cause they will charge you 6-7 hours if they can when in fact it is a 3 hour job. I was charged for 3.5 but only after it was clear that I knew a little bit about the problem. I would also take your car to a MB dealer, not the mechanic up the street. He will not be able to get the harness from MB. The policy is, as I understand it, that on cars upto 125K miles they (MBUSA) will supply the part but only if a dealer puts it in. And if they don't offer that at your dealer then call the local rep. and if that doesn't work call MB customer service. They are well aware of this problem and will not try to hard to avoid replacing it if you let them know you will not settle for less.
Good luck......and oh, by the way, don't let the dealer charge you for any time to "diagnose" the problem.....it IS the wiring harness. Have it opened right there and then or bring (tow) it to them already peeled back. Right where the coil/spark plug wires go into the main harness is a good place to look.
It will take less than 3 minutes to diagnose the problem.

 

\

Brian: I need a wiring harness for my 1995 S600. You mentioned that MB had extended a warranty to 125K miles, does this also apply to the harnesses in the S class models? And if so how do I find documentation of the extended warranties?

 

Hi....to the best of my knowledge the warranty is on the engine as aopposed to the model. The 104 engine is the one that presented the problem from late 93 to 95, in a couple of different models. I would check the forums' for your S class specifically. They would know if there is a problem that MB has accepted claims on. Good luck.

 

Thanks for the speedy reply. Do you know if anyone sells an aftermarket wiring harness for my '95 S600?

 

Unlikely......

 

I have a 1994 C180 and it's been a year now since my car starts running
after I try several times (3,5,8...or even 20 lately) to turn the key
into ignition switch. But every time the motor starts running it can be
heard a high "relay like" sound just a second before (I think it's the fuel pump). When this sound appears immediately after I put the key in the second position for the first time (like I think it should be every time) the motor always starts perfectly. But this doesn't happen anymore lately and the engine starts more and more difficult. Everything after is working OK.
PLEASE HELP!!!! Thank you in advance!

 

I've read all I can find but still can't find the answer. My 300e has fuel and good spark but won't run...is the OVP still suspect. Here is the problem:

Vehicle wont start. 1992 300E 180K Check engine light on for past 50K. Car is a dailey runner about 50-100 per day no problems...Car sat overnight, would not start in AM (mild temp), tinkered around in the engine compartment, pulled air cleaner, nothing much. 30 minutes later car started fine. I kept it running and drove home (40 minutes) no problems. I shut it off and restarted in my garage 2 times with no problems. Came out 1 hour later, it started but ran as if it were missing a cylinder, turned it off. Later that day, tried to restart...nothing. It turns over but no go. I replaced plug wires cap and rotor. Great spark to plugs witnessed. Removed fuel lead to 2 jets at motor, lots of fuel available to engine. I can't figure why it won't start. Good spark with good fuel suppply but no fire. Ignition Control Module? Can you think of anything I can try myself?

 

Replace the OVP relay first.

 

Well, it seems these cars are some real POS's. I have one thats a Cabrio. Car will turn over, but won't start. It has insane fuel pressure, but no injector pulse. Changed the crankshaft position sensor also. Checked and changed all fuses in the panel. What can be happening? I can spray carb cleaner or starting fluid in it and it will run off of it for a few seconds, and you can give the car a few pumps of the pedal and it will only idle for a few seconds. Can anyone out there help me?

 

Do you have spark while cranking? If not, most likely it is the OVP relay.

 

we have spark, got fuel pressure, but no injector pulse. We have replaced the OVP already also. No change. Did have a wierd condition though, a ground wire to one of the wheel sesnors on the front was melted like it got hot. Don't get that at all, but I replaced the ground too. So, we are back at square one. Crank, but no start.......and yes we do have gas.

 

when this happened to me i thought it was a fuse, but it wasn't. i replaced not only the ovp, but also the fule pump relay... no problems since then. have you tried changing the relay too?

 

Well we have fuel getting to the fuel rail also. We now have injector pulse also. We found we had a bad noid light. changed the ovp, changed all fuel, changed fuel filter, air filter, coolant temp sensor, and spark plugs.
Sometimes we can get in the car and try to start it and it will fire a few then die. Nothing else. The car will try to run if we spray into the plenum with starting fluid, but thats it. Could we have clogged injectors? When we changed the fuel filter it had a buttload of setiment in it. The car had been sitting for some time. The fuel pressure on the fuel rail is at 60+. I don't know what the fuel pressure is supposed to be. STILL AT A LOSS! I know that C4 maybe cheaper than fixing this thing!

 

hello friend

which really was the problem that the injectors not pulsing

* thank you