Technical Grande punto Abarth intermittent cut-out at idle and no start

[JCJ]

Evening all,

Been banging my head against the wall for months with this issue, hoping someone here may be able to help!

Sometimes it won't start, it's turning over at the right speed but won't fire, after maybe 15 attempts it will start or after I come back the next day after spending all my money on taxis.

Sometimes it will just cut out when idling at traffic lights, then it may just fire back up or (more usually) I'll have to go through the above process of trying to get it to start again.

The conditions don't seem to have any bearing on it, it's happened when warm, when cold, when wet and when dry.

Things I've checked/tried/changed:

Cleaned throttle
New battery
Checked fuses
Checked brake light switch
Checked hoses for leaks
Added a secondary earth strap between engine/body and body/battery
New timing belt
New spark plugs
2 new crank position sensors (was convinced it might be this)
New cam position sensor
Sent the ECU for testing (they were 90% sure the ECU was fine)

The ECU has no stored or pending faults (checked with 3 different scanners)

Alternator kicking out a good voltage

Can hear the fuel pick up running when I turn the ignition

The problem periodically goes away, maybe 2-3 months with no issues.

Any ideas or knowledge will be greatly appreciated, don't want to get rid of her, she's good fun when she gets (and stays) going!

 

[nikrox]

Only things you havent changed are the leads and coil pack..

 

[JCJ]

Cheers nikrox, hopefully I can find a way to test the ones that are on there without having to buy new ones

 

[nikrox]

Personally I get mine from a local breakers..if the dont fix the issue they take them back and repay the money.
There's is a breakers on ebay who warranties his stuff. Top man,full
of knowledge.
He diagnosed my issue in 5 minutes..after a year of different attempts to fix it.
Mine was an eratic idle.

 

[Bernievarian]

I believe the coil pack is just four coils in a pack (hahaha), so unless the (common) grounding or feeding got loose they should NOT fail all together.
I'd suspect ECU power/ground (which in essence is the same potential issue) or even feed from the key switch / power relay.
An intermittent problem is the worst to solve, try to make it permanent, by removing fuse, disconnecting wire, removing relay ONE AT A TIME to get the same problem PERMANENT and you'll be on the right track, though it could take a large amount of time/energy/will ...

BRs, Bernie

If someone here helped You fix -or better, understand- your issue, hit the thanks icon @ bottom right corner, it's free and makes us feel helpy ;-)

 

[nikrox]

indeed the coil pack is one unit..i pay £15 for them,inc leads from my breakers yard.

 

[JCJ]

Cheers Bernie and nikrox, yeah it has 4 individual coils, will check the common wiring for them and grounding, I've also found the specification for the coils so can check their resistance is where it should be. I was going to check for any chafed/broken wires this weekend, so I'll start with the ecu power and ground ? I have tried swapping relays around previously, thinking that it was the fuel pump relay but will give this another looking into.

Would an issue with the ignition barrel wiring to the ecu show up with any lights on the dash?

Intermittent problems are the worst, I'll keep chasing it though! ?

Thanks for your help guys ?

 

[nikrox]

Apologies..the coil pack on the GP's I have worked on,all two of them,have a single coil pack..with four,individual plug leads.

 

[JCJ]

Did a bit of work today, went round all the ground points and cleaned them up. Took out each of the coils and read their resistance, whilst I had them out, had a look at the spark plugs as well.

The resistances were 1.2-1.4, 1.3-1.5, 0.9-1.1 and 1.2-1.3. These are above spec so could possibly need replacing but they aren't wildy different than each other, so it isn't like I have one bad coil that's causing issues. Spark plugs looked OK to me.

Checked for continuity between ecu plug and ground on all three ground pins, these were all fine. Inspected the ground wires anyway, these seemed in good condition.

Found that I could replicate the problem by cutting all power to the ecu (by pulling both its fuses). So pull out the loom between the engine fuse box and ecu, took off the conduit and checked that none of the wires were broke or chafed which they weren't.

This has me thinking that the problem is now the supply to the fuses, so my next port of call is to change the ecu relay. I'm also going to chase the wires that supply the relay to once again check for chafing/breaks.