Hello I have an intermittent misfire. My code reader reports p0352.

The problem.....
On initial cold start, it starts on 3 and within a few seconds fires up to 4.
Once warm and the car is restarted, the misfire is pretty much constant. (This makes me think heat related).

What I have tried so far.....
Swap coil packs over - No difference, still get p0352 (even after clearing code). In my mind that takes the coils out of the picture.
When misfiring, I've pulled the leads (using insulated gloves), the misfire is from number 2.
Pulled plug 1 and 2, visually checked OK, in fact they look new.
Swapped plug 1 & 2. Still same fault/code.
Visually checked 1 & 2 HT leads.
Swapped lead 1 & 2. Still same fault/code.

What I am now thinking.....
Compression testing all the cylinders.
Injector fault.
Wiring fault.
The fault doesn't match the ECU failure posts I've read.

I bought the car with a suggested injector fault. So I would not be surprised if that is the problem. Searching the forum, injectors are suggested, so is the ECU (see above). I've also seen mention of injector cleaner solving the problem.

Before I start the process of digging deeper into the engine, I thought it would prudent to ask people who know this engine better than me. One confusing bit of information I found suggests this is a SPi engine, it certainly isn't.

Thanks in advance.

Dave

By 'swap coil packs over', do you mean you've swapped in new ones - or just swapped the two over that are already there?

If you've swapped the ones that are already there, does the fault move from number 2 to whichever is connected to where number 2's HT lead was connected to?

You also haven't actually said what car or engine you have!

Thanks for the reply.
I've swapped the two over, not replaced. Regardless of what I do, number 2 misfires. The code hasn't moved at all.

Yes, my lack of car information was a stupid oversight, sorry.

Seicento 2001 Abarth 1.1 sporting. I think it's the 8v OHC, MPi setup.

Dave

I don't think the fault code refers to a specific cylinder, does it?

If I were you I would replace the ht leads. About 20 quid from a motor factor.

Have a look at it running in the dark and look for escaping sparks. Unless this is what you mean by 'visually checking leads'.

They sound like a vw beetle running on 3 dont they ☺

purf said:

I don't think the fault code refers to a specific cylinder, does it?

If I were you I would replace the ht leads. About 20 quid from a motor factor.

Have a look at it running in the dark and look for escaping sparks. Unless this is what you mean by 'visually checking leads'.

They sound like a vw beetle running on 3 dont they ☺

Click to expand...

Thanks for the reply.
No the fault doesn't point to a cylinder, but removing HT lead 2 when it's misfiring doesn't change the engine noise, so I'm happy the fault is there. The fault code points to coil pack B which runs cylinder 2&3. Therefore if the fault was the coil pack, I'd expect the code to change when I swapped the 2 coil packs over. If the fault was the spark plug, then when I swapped the plugs over, I'd expect the problem to move to cylinder 1 and therefore fault on coil pack A. But it didn't. The same with the HT leads, when I swapped 1 & 2 over, if there was a fault there, I'd expect the code to move to the other coil pack, but it doesn't.

You are right, it doesn't sound well at all misfiring. I visually checked the leads for damage, as previously I have been able to see splits or damaged ends. I haven't tried it at night. But as I've said above, I would expect the fault to follow the faulty component, but it doesn't. It sticks with cylinder 2.

I suspect the code is not really telling me the full story and maybe it's even leading me in the wrong direction altogether? At this stage I am quite happy the coil packs/leads & plugs are not the issue.

As the fault is heat related, if I follow the code, this would suggest a problem on the low tension leads to the coil pack, or the ECU. The symptoms don't match what I have read about ECU failure (IE constant, NOT intermittent). I just can't imagine why the code would refer to a coil pack, if I can see sparks from the plugs.

It's a proper head scratcher.

Dave

have you checked the compression on all cylinders as low compression could give a missfire

Is it possible to swap ht leads 1 and 2? I thought they were different lengths and would not reach?

rick500 said:

have you checked the compression on all cylinders as low compression could give a missfire

Click to expand...

This my next idea, unfortunately the weather is working against me and I refuse to work in the rain

purf said:

Is it possible to swap ht leads 1 and 2? I thought they were different lengths and would not reach?

Click to expand...

Yes, they do just about reach. Not ideal, but for test purposes, it will work with a little re-routing. (EDIT - I'm running the engine without the airbox for this testing)

Thanks again.

Try getting a long screw driver and putting it on the injectors as a dodgy injector could cause it to be misfiring. What your looking for is a difference in noise to the others whether it be quiet or if it's missing a tick every now and then.

crazySnublz said:

Try getting a long screw driver and putting it on the injectors as a dodgy injector could cause it to be misfiring. What your looking for is a difference in noise to the others whether it be quiet or if it's missing a tick every now and then.

Click to expand...

Good call, an old school idea I'd not considered!

I finally got some time for a more extensive poke.

Compression test came back even but quite low. Circa 65psi on all four. Is this normal? This is the first time I've used this compression tester after my last one went AWOL so there is a chance it's just the meter.

I tried the long screwdriver on the injector and my ear on the other side. 1&4 were clear and loud, 2&3 noticeably quieter, if there at all. So with the engine running, I unplugged injector 2, no difference to the engine tone. Reconnected and did the same to injector 3, again no difference in engine tone. I am now suspecting both of these are beginning to fail. How this has manifested its self as a coil pack fault, I still haven't worked out.

My next action is to connect the spare injectors I have to the loom only and have a listen to them, to make sure they work. If so then it's strip down time.

At this point my phone rang, my mate was sat on industrial estate with a glowing brake disc. Deviator breakdown services get called out once again : I will update when I make more progress.

Thanks for the ideas.

In my opinion 65psi is a bit low but seeing as it's a new meter and you could just need sometime getting used to it. Did you try a wet test?
If they were equal I wouldn't be worrying to much about it being compression or otherwise you'd have misfires on all four.

In my experience I've only seen the bmw', merc's etc come up with injector codes as well as misfire ones of this era, all the others have thrown up misfire codes. If 2&3 injectors aren't working correctly it's going to be putting extra strain on the coil pack hence why your getting the misfire and the code relating to that coil pack.

Sorry for the late reply, I've only just got around to fixing this issue as the early arrival of Mini Me delayed things somewhat.

The further stages I've been through (and random ramblings!).....
Swapped both coil packs over - No difference
Swapped HT leads over - No difference
Visually checked all 4 plugs for a spark - All present.
Visually checked all 4 injectors - Cold start so all four fired.
Swapped 2 injectors in for the 'recorded faulty' ones - No difference
As the plugs spark and the injectors fire, the wiring is also ruled out.
Even though there was no other indications to suggest a blown fuse/relay, these were all checked too.
Earth to both ECU and engine were checked.

Even though I'd ruled out the HT lead, coils and plugs, I felt I had to replace these regardless as I needed to know I was working with good parts. Also after reading the horror stories of fried coils knackering up ECU's, I had little choice. Once replaced with new, decent parts - it made no difference what so ever!

At this point I was as certain as I could be that I was dealing with an ECU fault.

I went away and studied the internet/technical manuals to see if there was any other avenue to explore first. Unfortunately not. As such I started to research the ECU and setup procedure. Then I finally ordered one from eBay....... The day arrives, I plug it in. I reconnect the battery, I follow the setup procedure I found on this very forum (Thanks) and I got 5 codes back instead of 1. 1 of these 5 codes was Coil Pack A. I reached a low with this car. I started to look at what it worth in pieces. I sent the ECU back to a rather miffed seller who was insistent it wasn't the ECU. I explained all the steps I had gone through, he tested the ECU and came back to me, he'd loaded M3 software instead of M1. At first I was relieved, but then I wondered if my car had suffered any other side effects.

A couple of days later, another ECU arrives. I plug it in, setup it and I now, finally have a working car. No apparent side effects from the wrong ECU.

Thanks for all the help and advice.

Well done. Some people would have given up with it.

purf said:

Well done. Some people would have given up with it.

Click to expand...

Thanks for the support, but giving up is not my style, also I really, really hate stripping cars. I still have parts from every car I've ever stripped. In fact there is one outside half stripped, but became a lower priority.

I am a hobbist mechanic with a lot of tools and very good support when things go over my head. I couldn't let something like this win! Like every project, it has it's ups and downs.