MK3 Gti advice pls...

[gti_mk3]

Posted on the MK3 forum but thought I would try this one....

my brother's mk3 gti 8v will not start, so having an identical car I suggested swapping a few bits over to try and diagnose the problem.....

His car had intermittent starting problems then one day it refused to start at all. The AA said that it looks to be the coil, as there was no spark at the coil. We swapped the coil with the one on my car, no difference. We swapped the ECU and fuel pump relays, no difference.
We then decided to swap the ECUs over, my ECU on his car, still no start. His ECU on my car - my car would start then cut out after a few seconds (doesn't the immobiliser cause this anyway?)

So thinking that his ECU is not the problem, we are now stuck. Any ideas?

Cheers in advance, and great website by the way,

Chris

[topher]

you say there was no spark at the coil, have you tested if there is any power getting to the coil in the first place ?

[Len]

Was told that ya cant swap ECU's coz they are coded.

Sounds as if its a wiring problem. Have ya checked the main cables and connections and earths??

[gti_mk3]

haven't had the chance to go over the wiring much.
will get the multimeter out and see what the deal is.

Thanks for the advice...

[Len]

Might sound daft - but also check the battery terminals.

On other cars it can be things like sensor connections. On my Peugeot it was the water temp sensor, which goes straight to the ECU.

Silly things like that can cause intermittent problems.

[gti_mk3]

you say there was no spark at the coil, have you tested if there is any power getting to the coil in the first place ?

Ok, have tested some of the wiring and getting 12v power to the coil with ign on and immobiliser dis-enabled.? which leads me to think that it can't be the coil.

any other ideas?

 

[Len]

Have ya taken the plugs out to see if ya get a spark at the plugs?

I assume the starter motor is working, so its turning over but not firing.

If ya take all the plugs out and reconnect them to the leads, then turn it over u will see the sparks or not and also smell if u are getting fuel in as well. Put a rag over the plug holes coz the fuel will shoot out.

[gti_mk3]

done this, no spark at the plugs.....

 

I assume the starter motor is working, so its turning over but not firing.

correct..

[Len]

So ya got 12V at coil but no spark at plugs.

In that case its got to be cap and rotor, coz if it was plugs and leads u would get some intermittent or weak spark.

But it could be all of it - coil as well. Oh no u said u swopped coils didnt ya.
Yeah try dizzie cap and rotor first then plugs/leads.

[mrwotto]

May be the rotor arm / dizzie cap, as if it was the leads it is unlikely that all 4 would die at same time, so try that first,  actually may be worth checking ht lead from coil to dizzier cap!