ABK engine pinking / pre-ignition

[audi80mk4]

My 1992 80 2.0E pinks when hot and under load, e.g. accelerating or climbing a hill. It has the ABK engine, auto gearbox, less than 89000 miles, recently serviced, no fault codes found after thorough check.

Can anyone suggest a reason please ?

Cheers
Keith

[scotty33]

pinking could usually be down to overadvanced ignition timing, too high compression ratio (skimmed head?) or low octane fuel.
I guess the knock sensor could also be faulty, but if so it should have shown up on the code read?

[sdk778]

If anything like mine you need to get the dizzy timing adjusted, strobe light on the dizzy markings, as stated sounds too advanced to me.
Nothing drastic just need to find a good spanner man with the brains and the light!!!!

[audi80mk4]

Thanks very much Scotty and SDK (is the pic of you ?!!)

My good spannerman says he can't retard the timing without reducing performance. The head has been off (cambelt tensioner self-destructed, pistons clouted valves) but don't know if it was skimmed - I'll try to find out. Thanks for that thought. I can't remember if it pinked before that episode.

The pinking doesn't seem to be fuel-related, and I tried a different knock sensor without success. I'm hoping someone is going to say 'ah, yes, it's usually the blodging widget on the ABK engine' but perhaps I'm too hopeful :-).

Cheers
Keith

[sdk778]

Thanks very much Scotty and SDK (is the pic of you ?!!)

My good spannerman says he can't retard the timing without reducing performance. The head has been off (cambelt tensioner self-destructed, pistons clouted valves) but don't know if it was skimmed - I'll try to find out. Thanks for that thought. I can't remember if it pinked before that episode.

The pinking doesn't seem to be fuel-related, and I tried a different knock sensor without success. I'm hoping someone is going to say 'ah, yes, it's usually the blodging widget on the ABK engine' but perhaps I'm too hopeful :-).

Cheers
Keith

No, that's the wife ( I wish)

Mine lost a teeny weeny bit of performance when it was retarded, you hardly notice the difference, fuel economy jumps up too, so a few penny's saved there, all i can suggest is get him to drop it back a few deg and try it, i had the same with mine, he would play with it, i would drive it, then he would play again and so on.

Try a higher octane fuel, optimax or BP ultimate etc.., may be woth a go.

[scotty33]

If the head was skimmed or the piston crowns are coked up, the compression is higher than oe spec, either higher octane fuel is required or timing needs to be retarded to suit. Yes there would be a small hit in performance but better than a set of damaged pistons/bores?
The only 'widget' I can suggest checking is the infamous Relay 30 which seems to cause a variety of ABK problems, but I have not heard of it causing pinking...
I posted the location and photo's in this thread if you care to check it?:

https://www.vwaudiforum.co.uk/forum/s...?t=2946&page=8

[audi80mk4]

Hi chaps, thanks for all your input and info

Optimax may have helped a bit when I tried it some time ago, but look at the price now ! Don't want damaged pistons etc, although another spannerman (a VAG-trained friend who ran a 200 turbo engine in a coupe quattro - it pinked like hell at first) says there's not much risk of that. Spannerman says the head would have been skimmed very lightly as it wasn't overheated, and the skim was compensated for by a thicker head gasket. My pistons are never coked up

First I think I'll try this, posted by marki in the thread to which scotty referred : "I needed to change the cambelt.Mine has 140,000 on 2.6 V6. The night before I disconnected the battery to reset the ECU.( i think it takes 10 hrs to reset) This is a common method used by the Japs. The ECU can 'drift' as the engine wears and parts are changed. ....It then relearnt itself. Now, in the morning before I took it to the garage I did notice smoother running !"

If that doesn't do it I'll retard the sparks, and after that I'll hunt down the villainous Relay 30 and check it. The plugs fitted are NGK BUR6ET, one grade colder than recommended - anyone know if NGK are a no-no for the ABK engine ?

I've been trying to think of some pearl of wisdom I can offer, this being my first thread an' all, but I fear such gem will have to be the solution to this one !

Many thanks again.