Gti That Only Starts 2Nd Time Every Time. ?

[happypatrol 5]

So I've had my car for a few years now. I've not done much to it for a while as I was renovating my new house and others. But now the times came to do the last bit. Fit my new engine. But before hand I've got the worlds most annoying fault.

 

The car only starts second turn of the key. It will not ever start first turn. I've traced the fault to the spark. On first turn of the key I get one spark at the plugs then nothing. I turn key off and Back on to crank again. And hey presto it starts. Sometimes it will take third attempt but it's always lack of sprk. Once it starts it runs no problem.

 

This has drove me mad. The last time I gave up and didn't look at the cat for a year. I'm desperate to get it sorted this time. Any ideas appreciated.

 

I had thought it was the tach relay. But I've even tried sending a permanent live feed do the fuel pump and ecu pins. Still nothing.

I also thought it was the immobiliser. A toad alarm. Cat 1. But it turns out its not actually connected to any fuel circuits and I can disconnect the whole system and the car does the exact same thing.

 

Any ideas appreciated.

 

Thanks

[Anthony 1,003]

Check the condition of the dizzy flylead and the 3-pin yellow plug where it joins the main loom. Quite often this is in poor condition and corroded, which causes odd starting issues like this - in my case it was usually a car that wouldn't start on cold mornings but would later in the day when it had warmed up!

 

If you get a single spark on ignition-on then I'm assuming that there's 12v to the coil and that the ignition amp is working.

 

The fuelling side of things on Jetronic is not connected to the ignition side, other than the ignition supplying the timing pulse to the ECU. As such, it won't be the tachymetric relay or anything like that, as that's purely for the fuel side of things.

[happypatrol 5]

Thanks Antony.

 

Is it possible to replace this part of wiring or is it a while loom. I've never been happy with it. A while back I had trouble with connections going into the amp. They're all there and tight but don't look great. Id be happier replacing it.

 

Does the ignition amp get a pulse signal direct from the dizzy to the amp ???

 

I was trying to test voltages at the coil tonight. But I need a hand. So will need to wait till I got someone here to crank it. But should I have 12v on one side. And a varying voltage on the other as it seems to change when engine gets cranked. Down to maybe 6v. I should probably test that properly again before quoting u numbers. But it's hard trying to crank it and look at the same time ????

[Anthony 1,003]

Yes, dizzy signal triggers the ignition amp directly through that cable. Its a weak signal so poor connections can easily cause issues.

 

I'm not sure how well you'll be able to test the coil using a standard multimeter beyond that there's +12v with the ignition on. If you have that and no spark, it'll almost certainly be something related to the dizzy pickup, amp or wiring inbetween though.

[happypatrol 5]

I agree with what you say. I just don't get why it always atarys after the second go. It's really strange. I'm taking the engine out. So maybe best just get it out and inspect the loom better when it's out. I guess I could maybe Tryn test the resistance in the associated cables.

 

Wiring isn't my strong point. But I'll give it a go.