Technical ECU/Coil problem - further question

[Tim C]

Hello all,

First of all I'd like to say a huge thanks to people who have posted on the dreaded ECU/coil issue - I've been reading the posts and they've helped a lot.

I have a 2006 Punto Active 8V, 1.2 that has been intermittently running on 2 cylinders. The engine light sometimes turns off but then soon comes back on again and soon after that the car is running on 2 cylinders again.

I've followed the checks from the 'Punto coil-ECU checks' thread and identified which coil isn't firing. The test light shows the steady flickering so the ECU is sending the negative trigger/pulse.

So what should the next step be? Considering it has been an intermittent problem does this suggest that it's NOT the coil? Should I replace the spark plugs/coil pack/leads at this point? Are there any other things I should check first?

Thanks in advance for any help - I'm new to this so need it spelling out!

 

[Ziggy122]

Hello all,

First of all I'd like to say a huge thanks to people who have posted on the dreaded ECU/coil issue - I've been reading the posts and they've helped a lot.

I have a 2006 Punto Active 8V, 1.2 that has been intermittently running on 2 cylinders. The engine light sometimes turns off but then soon comes back on again and soon after that the car is running on 2 cylinders again.

I've followed the checks from the 'Punto coil-ECU checks' thread and identified which coil isn't firing. The test light shows the steady flickering so the ECU is sending the negative trigger/pulse.

So what should the next step be? Considering it has been an intermittent problem does this suggest that it's NOT the coil? Should I replace the spark plugs/coil pack/leads at this point? Are there any other things I should check first?

Thanks in advance for any help - I'm new to this so need it spelling out!

If you are getting the negative pulse id say ecu is fine

Ann intermittent misfire on 2 cylinders woukd make me say coil pack

Change the whole lot
2x coils, new ht leads and spark plugs

Dont buy cheap coils, they dont last... buy branded ones
Ngk plugs are factory fit, and are pefect and ht leads from your local supploer will be fine

I did the whole lot after I lost 1 coil pack after traveling
As last thing you want is feedback blowing the ecu


Ziggy

 

[Tim C]

Thanks so much Ziggy, that's really helpful. I'll do that then and replace the lot.

One more quick question - is the term coil pack interchangeable with ignition coil? I've seen some breakers selling what they call coil packs but most suppliers selling individual coils - I take it I can just buy two ignition coils and replace them like that?

Thanks again!

 

[flisko]

yes

 

[Ziggy122]

Thanks so much Ziggy, that's really helpful. I'll do that then and replace the lot.

One more quick question - is the term coil pack interchangeable with ignition coil? I've seen some breakers selling what they call coil packs but most suppliers selling individual coils - I take it I can just buy two ignition coils and replace them like that?

Thanks again!

Yes the coils are held in place by 4 allen bolts
Simple disconnect - remove bolts and pull coil out simples

I think i took battery out and plastic trim around - it means i could get a ratchet and tip in instead

ziggy

 

[Tim C]

Hello everyone, I've been away and so have just got around to trying to sort out the Punto. I had identified the rear coil as the one not firing, using the test light as described on the thread on this forum. Tonight, following the advice above, I put in new coils, spark plugs and leads. With bated breath I turned the key but sadly the car is still only firing on two cylinders, exactly as it was before.

Do you think this means that the problems wasn't with the coils, or perhaps that the ECU needs to reset itself for the new coils to kick in? Any advice on what to do next greatly appreciated. I'm guessing now might be the point to take it to be diagnosed properly but it'd be great to know if there's something I might have missed. Thanks!

 

[Tim C]

PS all the parts I put in were brand new...

 

[oscar52]

Double check all the connections - and that the leads are in the correct firing order! (order is printed on the plate behind the coils if you didn't see it).


I know when I changed mine, one of the leads (cylinder 2) was a right pain in the arse to connect properly.

 

[Tim C]

I checked all the connections this morning - everything is in the right order and secure (each of the leads clicked on to their plug nicely). Still sounds like an angry lawnmower when I start it up.

One thing I just noticed though, is that there's a bundle of wires with two electrical connectors not attached to anything. They're on the driver's side right at the front and are just hanging there loose. I'm assuming this can't be a good thing - does anybody know if this could be something to do with the problem? The other end of them seems to be connected to the headlight unit, but all of the lights and indicators work fine. Photos in the next message...

 

[Tim C]

Photos showing the loose connectors and where they seem to join the back of the headlamp

 

[judderbar]

Photos showing the loose connectors and where they seem to join the back of the headlamp

That wire belongs to something else.

I am supposing a faulty ECU would most likely either work or not work. Intermittant suggests a wiring or earthing problem. There are some checks you can still do.

Start by cleaning the earth that is bolted to the body of the ECU - an easy job.

Remove the ECU plug and put it back on a few times.

 

[Ziggy122]

Grey is part of the a/c loom

Your like me - I have the same connector but no ac components at all!!

It was when the production line ran out of the specific loom for your car
Instead they stuck a higher spec loom in, cheaper then waiting for the part expensive loom in, cheaper then stopping

The same with the yellow connection, that appears to be a fog light connection


Ziggy

 

[Tim C]

Thanks very much Ziggy for clearing up the mystery wire! Looked more ominous than it is then.

Judderbar, thanks for your input. I've checked the earth all over the place (using a test light) and it seems to be good, both on the plate on the ECU and the black earth wire.

Still no joy though - running on 2 cylinders and I doubt I could beat Stephen Hawking in a drag race. Time to admit defeat I suppose and limp it to a garage...

 

[judderbar]

How many watts is your test light?

The coils require a surprisingly high current. You will need a 75W bulb at least.

Unless you load up the wires you cannot tell if there are problems there.

The connector can be faulty.

 

[Tim C]

Judderbar I'm not sure what you mean by loading up the wires, sorry. Not sure about the wattage of the test light either - it's a Draper Automotive Test Light, the brass type with bulb inside and a crocodile clip on the other end.

I tested that there was an earth between the battery and the bits that I tested.

And which connector do you mean?

 

[Tim C]

Update from the garage is that the diagnostics said there's an open circuit fault on BOTH coils. They said they'd need more time to figure out what that means considering the coils are new.

 

[Ziggy122]

Update from the garage is that the diagnostics said there's an open circuit fault on BOTH coils. They said they'd need more time to figure out what that means considering the coils are new.

Thats going to be wiring then

Could do with a donor car - running same coils to see whats going on
Swap em over - see if you cars cured - and donor is dying = Duff coils

if yours is still dead with a known working set

But it sounds to me like there is going to be a fracture in the wiring loom somewhere?

Ziggy

 

[Tim C]

Thanks Ziggy - I take it a wiring problem could be a minefield to diagnose then?

I don't have access to a donor car but these are brand new coils I have fitted - replacing the coils hasn't made any difference I can detect. When I checked with the test light before changing the coils the pulsing signal was coming in to the coil that wasn't firing so I'd thought it must have been the coil itself at fault. Not sure where to go now!

I'm taking the car back in to the garage on Tuesday to see if they can work it out, but I'd be keen to have another tinker if there's anything else you think I could do…

Thanks again for all your help.

 

[judderbar]

Thanks Ziggy - I take it a wiring problem could be a minefield to diagnose then?

I don't have access to a donor car but these are brand new coils I have fitted - replacing the coils hasn't made any difference I can detect. When I checked with the test light before changing the coils the pulsing signal was coming in to the coil that wasn't firing so I'd thought it must have been the coil itself at fault. Not sure where to go now!

I'm taking the car back in to the garage on Tuesday to see if they can work it out, but I'd be keen to have another tinker if there's anything else you think I could do…

Thanks again for all your help.

A wiring problem should be easy to resolve if you can work methodically and you have some idea of what you should be doing.

I tried writing out some detailed instructions but the chances of you messing it up are a bit high if you do not know what you are doing.

FYI though, the coil circuit current while only operating for tiny moments of time requires at least 6-10 amps to flow thru the ECU to ground for each spark and since you already have an identical working circuit, in theory it should be easy to check what is working and what is not..

 

[Tim C]

Thanks Judderbar. I wouldn't say that I know what I'm doing but I am very keen to learn! Are there any resources you could point me to that would help me to identify where the problem is?

The local garage had another look at it yesterday and managed to get a better diagnosis; the error message I've been told was 'random multiple misfire on coil 1'. They've said that they'd recommend taking it to a Fiat garage as they'll have better diagnostics kit. I'm keen to try to sort it myself if possible though as the nearest Fiat garage is quite a drive away and the 2-cylinder misfire is no longer intermittent. Don't want to risk causing further damage by driving it a distance...