Andyr_123

I bought a 1993 Audi 100 about 2 weeks ago.
I filled it up with 77 litres of Shell Optimax unleaded fuel which i believe has an octane level of about 98/99.

Since then my engine has been 'pinking' ('hunting'). Is it the fuel i put in that's the problem?

Also when i start the car when it's warm (it's fine when i start it cold 1st thing in the morning), the Revs go down to about 600/700 RPM, then up to about 1200RPM and keep going up and down for about 10/15 seconds, also the car occasionally back fires.

Any ideas what could be the cause? (I had one suggestion of it being the fuel pump, does this sound right?)



thanks

MikTip

Sounds more like timing & ignition problem?

20VT90q

Also look at the o2 sensors, my bet is they need to be changed. I had a "hunting" idle before they were swaped out, bad fuel economy too. Backfiring can be a sine of fuel delivery issues as well.

Andyr_123

I have adjusting the timing very slightly.
This has definitely improved the 'pinging'.

I think the pinging is still there but it's not very noticable now. i will see how it goes over the next few days and adjust it more if necessary.


thank you very much for the advice....very helpful

Andyr_123

adjusting the timing has stopped the engine hunting and mis-fireing, however the 'pinking' is still there.

i don't really know what it could be to do with.


has anyone elses engine been 'pinking'? if so, how did you overcome it?


thanks