electrical problems...

[col320ce]

I've just bought a 1993 320CE Sportline (australian) 230K km, auto, full MBSH...

I'm told the wiring loom has been replaced...

Drivers door central locking intermittent, fine if you use door or boot lock.

temperature gauge for outside temp occasionally flickers and reads low readings (about 10-15 degrees celc. under estimating temperature.

rear headrests don't go up or down.

car feels like it miss fires (rumbles) when ideling

oil gauge jumps around a bit too when ideling

Any ideas where to start with any of these? Is there a possible common connection problem here?

Thanks fo any help...

 

[meanie]

"I'm told the wiring loom has been replaced..."
By this do you mean the engine loom?

"Drivers door central locking intermittent, fine if you use door or boot lock."
Almost certainly drivers door unit, but not gospel.Check for signal at the vacuum pump ( under the rear seat base,drivers side) when operating.

"temperature gauge for outside temp occasionally flickers and reads low readings (about 10-15 degrees celc. under estimating temperature.
oil gauge jumps around a bit too when ideling"
This will probably be their respective sender units,but check dash connections,earths etc first.


"rear headrests don't go up or down."
The rear head rests only go down automatically,they have to be pulled up manually.

"car feels like it miss fires (rumbles) when ideling"
Is the missfire slight?
Or is it a rumble?A rumble would point to a worn bearing in something such as the alternator,poly belt idler etc.Or maybe the cam advance mechanism worn.More info would be good.

 

[col320ce]

The ideling issue is slight. Just at the traffic lights the revs will change. Not sure if there is a miss fire or not ...

There is a 'control knob' under the bonnet which should be changed to the type of fuel being used. It has numbers 1-5 (I think), currently it is on 4 (as it was whan I bought it). But it says that if I use 95RON or higher I should change it to 1 (and I am using 95RON Unleaded). I'm not sure what this dial does - whether it affects the timing or not. But maybe this is the problem???

 

[meanie]

It alters the map on the ECU slightly so reset it to suit the fuel that you are using.
It may have a weak coil ,lead or plug cap.
Run some quality injector cleaner through it & give it a bit of a thrashing!
Slight air leak-read this post through,it will give you a couple of pointers.
http://forums.mercedesclub.org.uk/showthread.php?t=51592
Check for head gasket failing (is there any sign of oil in the coolant?).Something like this may be useful.
http://buy1.snapon.com/catalog/item...&group_ID=1505&store=snapon-store&dir=catalog