Engine earth connection?

[s2avantman]

I am in the process of trying to find out why my car is hesitating(possibly misfiring) slightly on acceleration. This is more noticable at a constant speed. The engine also feels slightly lumpy when idling.
According to the Erwin workshop manual for the ABY motronic fuel injection and ignition system. An earth connection should be made between the engine and right side member. This seems to be connected to the engine near the turbo and to the right side member below the inlet to the MAF. My car (93 Avant) does not have this and I would be grateful for any confirmation that it exists.

Karl

[S2central.net]

Can you pull fault codes from the ECU ?

It *may* be earth related but could be loads of other things.

There is a very important earth strap from the coil packs onto the rear of the cylinder head. I've seen that work loose on three ABY engines.

Cheers,

Paul

[s2avantman]

thanks Paul.

I have checked the earth lead for the coils and the two below the inlet manifold.

I pulled (after following your MIL directive)
2113. The cat light comes on after about 1 minute and is sometimes intermittent in slow traffic.
I have changed the hall sender and whilst doing so found the camshaft oil seal was leaking onto the old sender.
I have changed the oil seal.
Next thing is to work through the ignition
system, after that possibly look at the speed and position sensors and after that
back to the drawiing board.
Any further suggestions would be most welcome

cheers

Karl

[S2central.net]

Have you cleared the fault code in the ECU now ?

If not - just pull the MOTOR fuses for a minute to reset the ECU - if you still get fault 2113 then there must be a wiring fault related to G40.


Paul

[s2avantman]

Paul,

I Pulled the MOTOR fuses last night .
No fault was shown until about 40-50 seconds down the road and again it was the 2113 fault.
I will try and work through the wiring tonight. The ABY motronic manual gives a test procedure for this.
Reading through this procedure, it says that if all the tests are ok then replace the ECU. Could this possibly be the probelm?
On my to work this morning I noticed the CAT light went out whenever in stationary traffic and only came on whilst the car was moving or I when reving above idle. I was wondering with your experience and knowledge of G4 and G28, whether G40 idepends on these in anyway which would give the 2113 fault.
Thinking this because when idling no fault is present.
thanks again for your help

[S2central.net]

It's possible that an ECU fault could raise this error, but I doubt it.

Swapping with another ABY ECU temporarily would confirm that.

If it is a sensor problem, that could also be quickly tested with an oscilloscope and breakout box to see how the signals compare to a healthy setup.

Let me know if you need some hands-on help diagnosing the problem.

Paul

[s2avantman]

Paul,

Thanks for the offer of assistance.

I am going to continue working through the wiring and ignition system and after that If I am no wiser I will contact you.

I have also been advised (by my local Audi dealer) to check the speed sensor for cleanliness. Apparantly they pick up dirt from the flywheel over time. I noticed this in the erwin manual as well. It says check for metal swarf.


thanks again.


Karl .