Very uneven runnning.

[Jas11n]

Not my car, but my brothers 95 ABY coupe.
It's been stood outside in our factory carpark for close on three weeks now.
He got in last night, it started fine and was fine on the drive home.
Goes to start it again an hour later and it seemed to be running on 3/4 cylinders and very rough.
I'm guessing condensation has got in some of the multiplugs somewhere but not sure where to start?
Power output stages and coilpack wiring maybe?
I'll hook up vag-com when he gets here, in the meantime any ideas of where else to check?

Thanks in advance.
Jas

[Martynf]

coil pack and sender wiring plugs on the bulk head worth checking for sure. If its running on a few less cylinders then maybe just one of the two tci units on the bulkhead is the root cause of the fault. Check for damp, corroded terminals etc....

This is a curve ball, but I've seen it happen.... a rodent or something made the engine bay home for the three weeks maybe and and chewed through something to escape. Don't discount it!! I've seen it happen a few times!! :-0

[rotoryboy]

.... a rodent or something made the engine bay home for the three weeks maybe and and chewed through something to escape. Don't discount it!! I've seen it happen a few times!! :-0

He's had this already

[Jas11n]

He's had this already

Certainly has
Car was bought with very low milage so had been stood not used for a while. You should have seen the state of the under bonnet lining, some very cosy mice somewhere
You could actually see the mouses teeth marks on the injector boots
All that has been sorted though and all replaced over the summer months, Just seems to be condensation somewhere.
Over the last 3 weeks we've seen a low of -7 and a high the other day of +13

[Jas11n]

First port of call was fault codes pulled with vag-com.
One fault code - 00516 (N60) Throttle Position Switch open or short to B+.
According to Motronic manual possible reasons are;
1/ Wiring,
2/throttle damper,
3/ Switch itself defective,
4/ Dampness in multiplug.

I ignored this for the time being as that fault would not cause it to run the way it was.
We took the coilpack cover off, checked for dampness inside plug connecting tubes, and made sure all coilpack wiring was sound. Also checked plugs for tightness.
Next stop, power output stages for the coilpacks on the bulk head. We took off each multiplug and cleaned inside with switch cleaner.
Also cleaned all the injector multiplugs and any other ignition wiring we could see.
Problem was traced to one of the two heatsinked modules bolted to the bulkhead (Are these the power output stages?).
The offsides right hand multiplug has only got two small wires connected to it, and dampness was found to be in this plug. Cleaned it and she runs smooth as silk again.

Now to the Throttle Position Switch .
We cleaned multiplug and the switches connectors, code still came back. Next was to test the switch with a multi meter. Unplug multiplug and move to one side, test top pin and bottom pin for continuity while the throttle is closed. With the throttle closed you should see no continuity at all and infinate ohms when open. I saw infinate ohms at the closed position so this pointed to the throttle switch not registering that the throttle was closed.
I checked throttle damper to make sure that is was retracting fully and found that the throttle could be pushed a little further to the closed position.
Damper was fine, so then checked throttle cable and it was way to tight. Not tight enough to make the revs rise above idle, but tight enough not to let the switch close fully. Adjusted that and rechecked with vag-com, all sorted.

Bro is happy once again ,
And I've learnt a bit more

[4WheelDrifter]

Certainly has
Car was bought with very low milage so had been stood not used for a while. You should have seen the state of the under bonnet lining, some very cosy mice somewhere
You could actually see the mouses teeth marks on the injector boots
All that has been sorted though and all replaced over the summer months, Just seems to be condensation somewhere.
Over the last 3 weeks we've seen a low of -7 and a high the other day of +13

Maybe he should get a 8A0 998 100.

[Fat Audi 80]

Very interesting. Well done on your fault finding

Cheers,

Steve

[volcano rs]

now dont forget to coat it all with wd40

[Fat Audi 80]

Maybe he should get a 8A0 998 100.

That is a seriously Audi Part number geek joke!

[Jas11n]

Maybe he should get a 8A0 998 100.

Fry the little ******s

or maybe I should get a 4A0 860 283 for what I may end up doing to it one day
Joking, it's all part of the fun of these cars

That is a seriously Audi Part number geek joke

Part number envy ?

now dont forget to coat it all with wd40

Yep, all done.