Audi A3 + S3 (1996 - 2001) - 97 1.6 Curious starting problem

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Wed 5 Aug 2009 11:33
97 1.6 Curious starting problem - Tornadorot
My A3 has recently become very reluctant to start. First thing in the morning, it starts OK, but if the engine has been running in the previous few hours, it can barely turn the engine. If I try to start it immediately after switching off, it won't turn it at all.

In the morning, I checked the voltage across the battery terminals in situ, with the ignition off, and it was only 12.1V, checked again with the engine idling, and it was about 14.4V, so I decided the battery was on its last legs (it's just over 5 years old) and replaced it. Disappointingly, it was the same story the next day: OK in the morning, only just managed to turn the engine in the evening.

It was only after I bought the new battery that I realized the battery warning light wasn't illuminating at all when I turned on the ignition, which seems to suggest an alternator problem (diodes?) - but the fact that I saw a good charging voltage with the engine running seems to contradict this. Haven't got round to making any more measurements or checking for shorts yet. Has anyone seen these symptoms before?
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Wed 5 Aug 2009 12:13
97 1.6 Curious starting problem - madf
Have you checked the earth straps first?
Corrosion will reduce voltage and give symptoms as you describe...

There will almost certainly be one from battery to engine , to chassis and one from starter to engine..

Take all off and clean.


Edited by madf on 05/08/2009 at 12:13

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Wed 5 Aug 2009 21:07
97 1.6 Curious starting problem - adverse camber
I think that you are looking at the wrong thing. If it starts when cold then the battery/connections should be fine.

I would be checking the cam/crank sensors. Have you ever had it cut out when hot?
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Wed 5 Aug 2009 22:20
97 1.6 Curious starting problem - Tornadorot
No, it hasn't cut out when running. I've had a crankshaft sensor go before, and that was quite a disconcerting experience :-)

I found one earth strap, on the engine block (hidden underneath a coolant pipe). I cleaned it up best I could. Still no battery light on the dash.

However, I also found a small-gauge wire, which seems to go to the starter solenoid, has got pinched between two other cables and has frayed badly. I patched it up with insulating tape but I think it might need a better repair.
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Wed 5 Aug 2009 23:28
97 1.6 Curious starting problem - Peter.N.
I would check the voltage on the starter when its hot and the problem is apparant, if it much less than the battery voltage you have a high resistance connection somewhere. If the battery and starter voltage are more or less the same the fault is probably with the starter. Have you checked the battery voltage when the fault is present? if low could still be an alternator problem, it won't normally charge if the light doesn't work as it provides the alternator rotor exciter current.
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Sat 8 Aug 2009 00:17
97 1.6 Curious starting problem - Tornadorot
Well, I made a slightly better attempt at repairing the solenoid wire last night (it was practically worn all the way through) and since then I've started the engine 5 times on first turn, so that may have been the root of the non-starting problem. However, the battery warning light still isn't illuminating, so there's still something else amiss. I think I'm going to try earthing the alternator end of the warning light wire next, to see if that circuit is intact.
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Tue 11 Aug 2009 11:38
97 1.6 Curious starting problem - Tornadorot
Thanks for all the suggestions - I certainly know more about starter/charging problems than I did before. However, it has all become a bit moot now; I discovered on Friday that my local VW dealer had a new Golf 1.4TSI in stock as a result of a cancelled order, so I'm afraid it's scrappage time for the old girl.
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