So, here's the saga:
My A4 1999 Quattro driver's headlight failed about a fortnight ago. Initially I thought it was the bulb so bought a new one (at Ł60+VAT!). Took it to Audi as I didnt' want to touch the thing, they fitted it and said it wasn't that; they didn't charge though, which I was impressed by.
So, took it home and this weekend had a good old fiddle... but fixed it.
I removed the headlight to get the bulb out. The connector to the bulb had a black mark, like something had blown. I scrubbed it clean with a wirebrush and put the bulb back in. NB: I did, inadvertantly at this point try the headlights (with ignition on) and heard a funny buzzing/rapid clicking noise from the engine compartment.
Put all back together and headlights worked! Great!
Now, any sensible person would've quit whilst ahead. Not me ... I was on a roll, and was next going to fix my ongoing ABS problem. I checked every fuse, to no avail. I also removed the ABS controller connector, and refitted.
The following morning I went to start it and it just turned and turned but wouldn't fire. 2 days later, still won't start.
I've done the following:
- checked errors with VAGCOM. Showing 17833 evap purge valve n80 short to ground. Also showing water coolant sensor intermittant (this has been like this for months). Also I initially got MAF errors, but these have now gone, and I put them down to me driving it without the air intakes fitted for the fortnight.
- I've checked all the fuses in the side panel.
- I've checked the fuses behind the bolted drivers panel near the relays.
- I've taken out the headlight and re-fitted.
- I've removed the connector and tried headlights again (still buzzes/rapidly clicks ... so not sure if that's a sign that whatever relay it is is still ok?).
- Fully charged battery. Engine turns perfectly freely.
- Checked for fuel pump prime - sounds fine... not sure how else to check.
Not sure what to try next. Would the VAGCOM tell me if it was a spark plug problem?
One funny thing, if I remove the fuel pump fuse then try starting (with the fuse out) I get a short fire... this is the only way I can get it to fire.
I suppose the EVAP purge valve is the first thing to test as it's the only consistent and new fault. Any ideas how I start with this?