[V6-12v] TestingForSpark added to KB

[James Whitehouse]

If you're getting spark on the new coil, I'd eliminate that for now. Here
are some other possible causes for no-start situations you may not have
checked yet (FYI a Hall Sender problem should not cause a no-start
condition, according to the manual). On the other hand, most of these should
throw codes, and I gather you're not getting any:

1. Engine speed sensor - no signal
2. Ignition timing sender - no signal
3. Bad Coolant temp sender can cause starting problems in very low temps.
4. Supply voltage signal too small (e.g. Battery voltage below 10V, or
supply to ECU poor (bad connection, etc.))
5. ECU faulty

Although it shouldn't cause a non start, I'd also be inclined to check the
MAF sensor.

It should be noted that if fault no. 2 occurs while driving, the fault will
simply be stored. If it occurs before starting, the engine will not start.

If you have a gauge, you can check the fuel pressure. However, this requires
the engine to be started and idling. I think your problem lies elsewhere.
Either the faults above, or a dodgy fuel pump (assuming you're now certain
you're getting a proper spark on all the coils).

Other than those, I'd then look at a purely mechanical failure of some kind.

Good luck!
James



On 6/2/05 3:31 am, "Kent McLean" <kentmclean at mindspring.com> wrote:

> In my continuing quest to get my '94 100 S Avant to start,
> I pulled together a lot of suggestions, added what little
> I know, and created a web page describing how to test for
> spark. I tried to cover it all, from plug wires to Hall
> effect sensors, and the ECU itself.  Check it out here:
> 
> <http://www.audifans.com/twiki/bin/view/Audi/TestingForSpark>
> 
> --
> Kent McLean
> '94 100 S Avant
> '89 200 TQ, "Bad Puppy" is no more
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>