really annoying starting problem

[hipwell]

Got a 52 plate vw polo.

And the problem occurs totally randomly, sometimes itl work a week perfectly other weeks itl happen everyday.

Anyway the problem is strange, put key in, turn ignition, fuel pump fires up , turn key, starter motor cranks, engine will just not fire up. Sometimes it will enentually start if you pump on the throttle.

Ive changed the crankshaft sensor as advised by guilders who couldnt actually find the problem and just said change the crank sensor. Didnt work lol.

Ive cleaned the cam sensor, but the problem still persists.

Next on the list is to buy a new cam sensor but not if you guys can think of a solution.

Diagnostics machine shows no errors.

[g40jon]

sounds like it could be the ignition switch that is faulty. what engine is your fitted with? back in the day i used to own a 1996 mk4 1.6 glx and that would be tempermental as to whether it would start or not.
some days it would fire first time, others it would just turn over and not fire, occasionally it would even turn over!
another common problem area on the polos are the hall sender (which causes the car to randomly cut out whilst driving along) and coil pack, which normally presents itself as a random misfire at first.

thesew fault are pretty common on mk3, 4 and 5 polos. but im not sure which model yours is as 2002 is close to when the mk6 came out.

[nizuk1]

Hi,
I was just wondering how you got on.
I have a Bora 2000 V5 2.3 that has the same problem. At random times it won't start, twice a day or twice a month, hot or cold!
It was in the garage yesterday to check it on the computer, it shows no faults.

Any pointers?

Cheers

[Silvergrey]

I had a similar problem. turned out to be a faulty temperature sensor so the correct air/fuel mixture wasn't being sent through on ignition.

[riverwhy]

looking around various forums trying to resolve a similar problem on a bora sport petrol (see thread "bora starting problem") it seems that relay 109 (it's under the fuse box) can cause these problems on some VW models. Unfortunately it didn't help me because the petrol version doesn't appear to have a relay 109, but it might help other people. If you have similar problems and your relay 109 is the okd black one, then it's worth replacing it with the newer grey one, about £16 from VW dealers