Running Problem

[imadoofus]

I've got a problem with my coupe eek.

Two weeks ago, it started to idle rough, and was hesitating under acceleration, so I swapped out the plugs. The old ones were blackened, and had a bit of scorching on the ceramic, which suggests over-fuelling (too rich) to me. Running didn't improve, and as it was due a fluid change anyway, I dropped it into Craig Wilson yesterday (was hoping to see Jaymanek's 'Lorinser' CL600 there, but I missed him).

Craig checked the coil packs, and the ignition circuit and found no problems, so he pulled the injectors and treated them to some of that cleaning stuff - can't remember what it's called (something German, I think). He's told me to expect it to take 50 or 60 miles before the car returns to normal, and sure enough, this morning (5miles), it's worse than ever.

So: Any other diagnoses? Will a few more miles see the injectors cleaned out and fix my problem?

TIA

PJ

 

[Will]

What about the air mass side of things - causing it to run rich?

Will

 

[imadoofus]

Would it? If so, I guess it's worth checking. I know he mentioned the MAS, so I would guess he eliminated that, but I'll ask.

PJ

 

[grober]

LAMBDA SENSOR problem???

 

[imadoofus]

I've a nasty feeling this could become a very long list of possible culprits...

 

[television]

I've a nasty feeling this could become a very long list of possible culprits...

What is the car VIN please first 6 numbers

Malcolm

 

[imadoofus]

Wdb1240522

?

 

[television]

Wdb1240522

?

OK the two known issues are the OVP relay will give rough idle and stopping. to test pin 30 is the 12volt going in any pins 87 are the output, they should have 12v on them. Cant remember if it is the Irish or Austrian ones that are the worst, anyway they get badly dry jointed inside, there is only one replacement now with 9 pins, but it does work OK.
The voltage test will prove the point.
The other cause for stopping is the crankshaft sensor, we have had loads of those going down in the last few months.

Malcolm

 

[imadoofus]

Thanks, TV.

I'm not stopping or cutting out though. Just idling rough, and hesitating under load.

PJ

 

[imadoofus]

My car's still not right I could do with some more advice guys....

I had the ECU rebuilt. Replaced the coil packs, and the plugs. Problem is much improved.

However, car doesn't like to idle while in gear (5sp auto). It's fine in neutral or park, just not in gear. When you pull away, it almost dies for a second and then it catches, and away it goes. Seems to be ok once in motion, excpet it's reluctant to change into fifth.

Any ideas? I've replaced all them electronic bits; will I need to do the top end of the loom (which visually is in excellent condition), or is this something else.

I'm really missing my car now, and I need it made better again >sniff<

TIA

PJ

 

[Iain]

Plug leads?

 

[imadoofus]

Possible, I guess, but it's fine when running, and it's fine ticking over when not in gear..

 

[kth286]

Were the plug extenders under each coil replaced.

These are the extenders between the coil and the plug.

There are three in total and are about £9 each. There is a resistance wire in each and they are known to go bad as the wires get hot and go brittle making a bad contact on the top of the plug.

 

[imadoofus]

No they weren't.

Why would they affect tickover in gear, and cause a reluctance to go into fifth?

When the car is in neutral or park, it runs well, and other than the top gear problem, it's fine under way too.

PJ

 

[kth286]

because it is under load, which shows the shortcomings of an engine set up.

 

[Howard]

PJ , have you checked the vacuum lines ?

I had an incident of it not ticking over last summer , was ticking over at about 200 rpm and sounding awful..... wiggled all the vacuum lines , don't know what i did really but it's been alright ever since

I'm no mechanic as you might have guessed .....

 

[imadoofus]

Howard, I wouldn't know a vacuum line if it sucked me in the face

Truth be told, any car with so much as electronic ignition is pretty-well beyond my mechanical 'expertise'.

Andy Gayle has confirmed my suspicion that it's probably loom related, so he'll get the car next week, and presumably I'll get a bill for several hundred quid the week after.

Hey ho...

PJ

 

[kth286]

It will not be the loom at this very moment because a bad loom shorts out a coil, and at this point the coils are good because the car drives generally OK.

When a coil goes the car looses 2 cylinders and you definately know about it.

So just change the 3 plugs under the coils as I suggested - and problem will likely be gone. Dealers usually keep them on the shelves because they are in demand.

I have lots of experience of this.

A loom will cost around £500 in round figures (depends on the individusl spec of the car ie. ASR or not, ASD or not, manual or auto, 4 or 5 speed auto etc etc).

Fitting will be extra and allow perhaps 3/4 hours if someone has never done it before.

 

[grober]

Diy??

If its the loom?? and you want to DIY the wiring loom replacement or get a friendly auto electrician to do a homer and save a bit of money then heres how. PRETTY SIMPLE REALLY if you are methodical and use the old one as a guide.
http://www.mercedesshop.com/Wikka/M104WireHarness

 

[imadoofus]

If its the loom?? and you want to DIY the wiring loom replacement or get a friendly auto electrician to do a homer and save a bit of money then heres how. PRETTY SIMPLE REALLY if you are methodical and use the old one as a guide.
http://www.mercedesshop.com/Wikka/M104WireHarness

Andy Gayle said it's a two hour job, and for the sake of £100 I'll let him do it (if it's necessary)...

PJ