W124 260E wiring loom?

[Prof Riley]

After searching past posts about engine misfiring with W124s I think my 1992 has a wiring loom problem. Most posts seem to pertain to other models, but not the 260E. Is this model also prone to the breakdown of the wire insulation?

Symptoms are - usually fires OK when cold, after about 5 mintues or so it still runs OK at higher revs- 1500 or so, but will idle very rough and usually dies. It is then very hard to re-start until cold again.

Any help is much appreciated. We do love the car (when it runs) and would love to keep it for at least a few more years.

thanks,
Prof R

 

[television]

This should not be affected and the faults do not sound like that either

The OVP relay could be a reason, even if the ABS lamp is not on 119 in the link and just behind the battery

http://www.detali.ru/cat/oem_mb2.as...GM=717.433&CT=F&cat=15S&SID=54&SGR=040&SGN=03

Very hard to check as you cannot get to the wires.

Could you put up the next 3 numbers afte 124 of the vin

The ruskie link is going slow today

 

[bri957cc]

I'd suggest checking all vacum pipes as well.

I had a similar problem with mine, that was solved by replacing a split pipe.

 

[Prof Riley]

Thanks for your thoughts Malcolm. The number is W124 0262B XXXXXX. I do not believe that the car has ABS. About how much is an OVP relay cost?

Bri957cc, where did you find your leaky vacum pipe? That sounds cheaper, so will have a good look around.

Prof R

 

[television]

The first thing to do is to find the OVP relay, and if you have one check the fuse on top.

As bri957cc the vacuum pipes do get over looked, these will cause hunting, that is rpm going up and down

 

[Prof Riley]

Malcolm,
I just had a play around. I 'exercised' all of the relays in the back of the fuse box. All the pins and sockets looked clean and shiny. There was one that had a single fuse on top (but two holders) - I'm guessing that is the OVP relay. I did replace the fuse, it was a bit corroded, but no apparent break.

The car did start up- as usual. I ran it at speeds between 1200 and its normal idle, but just after reaching temp 80* (about 6 or 8 minutes) it was OK at fast idle of 1200-1500 rpm but, it began running very rough at its normal idle, then died.

Also- my mistake, the car does have ABS.

Don't know if this has any bearing or not, but the fuel gauge seems to be fluctuating while the car is stationary.

Prof

 

[television]

The normal warm idle for this car is 650-750.

It starts to get hard and all component need to be checked that could do this.

The rotary idle control vale is one such component, take out the plug and put 12v briefly across it and it should buzz

The plug on the side of the air flow plate, with an ohm meter it should be zero between pins 1 and 2 with the throttle closed and infinity between 2 and 3 with the throttle open

 

[Prof Riley]

Thanks again Malcolm,

The idle on its own seems to be about 8oo or so, but once the temp hit just over 80* it would not idle at all and died. It would not fire up again yesterday, but first thing this morning it did start and run. The battery was getting down so it is on the charger now. There did seem to be spark at the plugs when it would not start.

I don't have a multimeter, so will have to line up a friend. While he is here do you have any other likely bits to check?

Prof

 

[television]

The list for erratic idle when warm is

Air intake leaks
Airflow sensor plate or control plunger
Aux air valve
Cold start valve leaking
differential pressure
Idle speed and C02 content

These are in order for common faults

 

[The Crooner]

My experience is on a 230, but I think the system is similar.

Since its temperature related why dont you change the engine temperature sensor?

Mine is 4 pronged and sends signals to the FI and ignition, they are around £20 new from your dealer.

If you search for my started threads you will see all that I have done to chase down my idle problems, mine is now perfect when warm, hunts a little on startup, and when cold. I'm sure i have an air leak, probably on the inlet manmifold gasket, which I may do later as a part of a top end refurb.

Tony

 

[The Crooner]

Also take off, clean and refit all of the earth connections you can find on the engine wiring loom.

Tony

 

[piptronic]

Hey Prof R,

Did you sort the problem out with the 260E? I have the same car, and the same problem at the moment.

Any help would be much appreciated.

Thanks

Phil