Electrical fault 1994 E320 coupe

[grantmackay80]

Hi there,

I have rebuilt my wiring loom which wasnt in too bad a shape but glad I did it as it has solved the problem where the car would bog down when you try to accellarate hard. The car still has some faults the radio arial and the window wiper still have a mind of there own but I suspect the window wiper could be the stock its self but not sure. More importantly the car still revs low on start up at 700rpm then when warm it ticks over at 1500rpm. It goes down to about 900rpm when you put it in gear and drives well when your going, also when you rev the car in park or nutral it seems to dance when you get to 4000rpm but runs perfect when driving right up to the red line, it seems to go to tick over when you slow down about town so pulls a little.
The only other thing I can think that it might be is the wiring to the throttle body from the car.

Can anyone please help.

Thank again for your time Grant.

 

[grober]

There's a rev limiter kicks in when the car is in neutral/ park. My guess its your motorised idle valve that's faulty. Can be dirty and sticks or it could be the supply voltage from the OVP relay that supplies it.

 

[grantmackay80]

Thanks for the reply. I know the OVP regulator is behind the battery but can you tell me where the valve is located.

Cheers Grant

 

[grober]

M16/6

 

[kingdave]

I know it's not the main issue, but the wiper problem should be an easy fix.
You can pop the end cap off the stalk and get to the switch mechanism. If you blow the dust out of it and clean it up a bit scraping the contacts and put a bit of switch cleaner in.... in all likelihood you'll restore normal function. Take care when you open the end cap you don't let the spring and other parts ping off and get lost.

You could replace the stalk but it means spending money, removing the steering wheel and worrying about the airbag etc. so this is worth a go. Mine got to the stage where the wipers wouldn't come on sometimes or other times the intermittent wipe wouldn't turn off.

Search the web for handy pictures and instructions... here's a couple to get you started:
W124 Indicator stalk repair - Mercedes-Benz Owners' Forums

combination switch and wiper timer - Mercedes-Benz Forum

Good luck with it - should be a most satisfying 10 minutes!

 

[GP801]

On ours a new relay for £35 cured the random wipers.

 

[kth286]

Do you know you can read the fault codes for the engine control computer, quite easily.

It would be a good start as there may be some old fault codes still stored that need to be cleared.

Do some searches for HFM 104 Mercedes engine codes.

 

[hfmscan]

Diagnose HFM (pin 8) and E-GAS(pin 14, LED blinks faults) on diagnostic connector.

The system tells you that she does not like in sensors and perpetrators.
cutoff 1500 cannot be without error codes