Intermittent starting problem

[RichardS]

Hi there,

My first post - I'm hoping someone is able to help, please?

I do apologise for the length of the post but feel I should include as much detail as possible/relevant, to help diagnose the problem.

 

The short version is:

I have a 1997 Audi A3 1.8T Sport

My car sometimes fires, sometimes doesn't.

The dash lights  up, the engine turns perfectly, every time.

It just doesn't always fire.

 

The long version:

There doesn't seem to be a consistent pattern.

The only patterns I've noticed are:

1) At the same time on a Tuesday afternoon, I'd make the same 35 minute journey. Leave the car for approximately 2/3 hours then hop back in to drive home. Each time I tried to start the car again, it would turn over but not fire. By the time the 4th week came around, I parked in a place I knew I could comfortably leave the car overnight (as I was confident it wouldn't start - it didn't start).

2) A mechanic replaced the batteries in the original key as he said the voltage was a little too low. The problem then didn't happen again until my fuel warning light next came on (I'd been intentionally Keeping the tank over half full as I thought maybe the fuel pump was getting old and tired and that maybe the extra pressure from the additional fuel might help it out?). The very next time after attempting to fire the car after the fuel light came on, it wouldn't start (again, always the same problem - turns perfectly, doesn't fire). I'm not sure if the fuel light and the non-firing issue are connected or not - it just seemed like a strange coincidence.

Other (possibly) relevant details:

I have noticed that I don't hear the fuel pump priming as often as I used to - tired fuel pump or electrical fault?

The car has 130,000 miles on it and I've owned it from approximately 20,000. From that time, there's been an issue with the ignition barrel. It doesn't return perfectly from the 'starter' position ( is that position 3?), so each time I have to manually turn it back about an 1/8th of a turn, until it clicks (into position 2?). If I forget to, the dash lights up with warning lights - ABS, big red exclamation mark etc. If I just then make that 1/8th turn back, everything works perfectly. As I say, it's been like this from the start and has never caused any issues. I'm not aware of any more play in the barrel recently that could explain the starting issue but understand that this could very definitely be connected.

Recent work to (attempt to) solve the issue:

I took the car to my regular mechanic who changed the batteries in the fob and changed the fuel filter (at my request) - his less-sophisticated computer was showing a throttle body error (which he tells me has been there forever) and an imobiliser fault code, then nothing else obvious. He advised me to speak to an immobiliser specialist, who said he wasn't able to help when I explained the problem. In the meantime I spoke to my dad who had his immobiliser temporarily deactivated from a car he owned a few years back. I thought I might be able to do the same, to eliminate the immobiliser from the problems. I was recommended to a VW specialist who would have the computer necessary to immobilise the immobiliser 🙂

The VW specialist advised me that the immobiliser would be showing up as a problem and that disabling it wasn't the way to go. I bowed to his experience and let him run a full computer diagnostic. The diagnostic (and his experience) suggested the throttle body was a problem, so he disconnected it (presumably electronically?) and couldn't get the fault to repeat. I wasn't entirely convinced as the problem is so intermittent, I wasn't sure it could be diagnosed so easily but again, let his expereince lead the way, having the throttle body replaced - I now have a new throttle body and unfortunately still the same problem.

The same VW specialist is now suggesting that the ignition barrel is the problem (naturally I'm hesitant to trust him when he was so sure the throttle body was the problem). He tells me that there are 3 positions for the key in the barrel and that each carry a different voltage. He says that because the key doesn't return (as described above), the computer in the car is getting confused as to the key's position and is therefore causing the problem (turns but doesn't fire). Once he'd got to this diagnosis he said it was safe for me to take the car away, that it would fire every time as long as I very quickly returned the key from position 3 (starter firing) to position 2. I did as instructed and the car didn't fire in less than 10 attempts - so I still have the problem.

I'm reluctant to return to someone who has been wrong twice and the next alternative VM/Audi specialist mechanic can't see me for a month.

This is my only car so am very motivated to get it fixed.

If you've read this far, thank you.

If you have any advice/suggestions, they'll be gratefully received.

All the best,

Richard

 

 

 

 

 

[Justin Raza]

Have you fixed the problem? If so what was the cause.? I am experiencing similar problem but mine is cranking but not starting.