Technical Fiat Panda Shaking - P0351 - Powertrain Ignition Coil “A” Primary/Secondary Circuit

[DTanner]

So my wife took the car to Tesco tonight. When she was leaving, she started the car and it started shaking and the EML came on. When I turned up it started and seemed fine so I drove home.

Once on the driveway I turned it off and restarted the engine again. Shortly after starting the shaking returned. It is not violent but not right. I turned it off and on again and the shaking returned again but a bit stronger.

I read the error codes and it was:
P0351 – Powertrain Ignition Coil “A” Primary/Secondary Circuit

I captured a video of the exhaust sound here:


I captured a video of the engine bay sound here:


Is there a better (free) way to share videos than Vimeo?

Anyway, any recommendations on where I should start with diagnosing this? I will have a dig around the engine bay tomorrow to look for any signs but thought I would gather some ideas as I am not that familiar with this.

Some questions:

• Would swapping the existing coil packs around be useful to see if the fault moves with the change?
• Which coil pack is “A”?
• I think I can hear a ticking/clicking from the pack, does this suggest a fault (I am not certain on this, so will check tomorrow)?
• Any other areas I should focus on?

 

[koalar]

I just attach a video from my phone, as I would a picture

Need to be short

Better if it's a lower resolution, too high and some phones will not play it

 

[koalar]

Videos are helpful

You can here it's consist not firing from all the cylinders

 

[koalar]

If you swap the coils and the error code changes to another cylinder you know the problem is the coil

Or

If the error stays the same same you know the problem is not the coil

 

[koalar]

What's going on here

 

[DTanner]

What's going on here

I was looking for an electrical issue a few years ago and checked the harnessing. I wrapped some insulating tape over some sections to keep it snug. Nothing too interesting.

 

[koalar]

Code come back as coil 1

Most likely it's the one that goes to cylinder 1 and 4

Anyhow it's easy to double check, just pull the HT leads of the coil one at a time and start the engine

The ones that make no difference are the ones that are contributing little to the engine running

 

[09 johno]

looks like a 1.1 with the classic loss of power to the coil, the normal issue is a loose connection on the rear plug of the ecu, you could try strapping the plugs down tighter with tie wraps, but I found they stretch with heat, so I then added a wooden dowel to the top to give the straps something to pull against, that worked for about 15,000 miles. The actual fix was to take the back off the plug, with battery disconnected and a 20min wait to discharge any energy, I used contact cleaner on the plug and socket, then used an instrument screwdriver and forced each connection into the receiver then refitted the cap and dowel and tie wrap, I havnt had the issue since.

 

[DTanner]

OK. I have had to head off but had some quick checks this morning. The misfiring is a little intermittent but I did some testing this morning having provoked the misfiring (maybe more prevalent when the engine was warm but hard to tell).
I removed the lead for each plug in turn and restarted the engine each time. When either lead to the plug on cylinder 1 or 4 were removed (or both of them together) the car was misfiring in the same way (no change). With either 2 or 3 disconnected the engine would not start.
So seems the issue is with ignition on 1 or 4, which I believe is connected to coil "A" (the one towards the back of the car).

I have a multimeter, is it possible to measure the primary and secondary coil resistance - to check for a fault?

The Haynes manual says the primary should be between 0.52 and 0.62 omhs and the secondary between 6.83 and 7.83komhs.
I removed the electrical connector on the coil packs and there are two pins, the resistance across them is:
Coil A 0.8 omhs (seems too high)
Coil B 0.5 omhs
The multimeter was not providing a great reading so will double check this when I get home.

I assume this is the primary. Can I measure the secondary (Connects to the HT Lead)?

 

[koalar]

When they go faulty they normally still measure about right

But

If you swap the test leads over, the good coil is normally pretty quick to get to the final reading and the faulty coil is much slower


The simplest way to confirm a faulty coil is to swap them over and retest then you know 100% before buying anything

Saves having to manually check the power supply cabling and control circuits

Seeing it effects cylinder 1 and 4 together it's unlikely to be on the HT side in my opinion

When either lead to the plug on cylinder 1 or 4 were removed (or both of them together) the car was misfiring in the same way (no change). With either 2 or 3 disconnected the engine would not start.
So seems the issue is with ignition on 1 or 4, which I believe is connected to coil "A" (the one towards the back of the car).

Correct

 

[DTanner]

Ok so I retested the coil resistances and they seem fine for both coil packs. I measured as shown in the image below:

Primary Coil Spec (from Haynes Manual): 0.52 and 0.62 omhs
Coil Pack "A" = 0.6 omhs
Coil Pack "B" = 0.6 omhs

Secondary Coil Spec (from Haynes Manual): 6.83 to 7.83komhs
Coil Pack "A" = 7.2 komhs
Coil Pack "B" = 7.2 komhs

I swapped the two coil packs over (I physically moved them - as the loom connectors were too short to swap directly). However, I could not get the car to shake again. I can hear a light intermittent misfire but not a loss of cylinder and resultant car shake. I will try some more later and tomorrow to see if it can be provoked some more.

 

[DTanner]

Ok, so today the car threw the code:
P0352 – Powertrain Ignition Coil “B” Primary/Secondary Circuit

This is great news as:
1) I had a code: P0351 – Powertrain Ignition Coil “A” Primary/Secondary Circuit
2) I interchanged the two coils
3) I got a new code: P0352 – Powertrain Ignition Coil “B” Primary/Secondary Circuit

As the only change was the coil swap, and the error code followed the coil, then the coil was the issue. I identified Coil "A" as the defective one as when the car was misfiring the level of misfire was unaffected by removing the HT Lead from the plugs of Cylinder 1 and Cylinder 4 and these were connected to the coil pack towards the back of the car (see labelled diagram in previous post).

As I had swapped the coils for my test the defective coil was now in position "B" so I simply bought a new coil and replaced this one. I was careful to delete the error code and then restarted the car. It immediately (and very briefly) misfired and threw a new code, and then switched to running smoothly. The error code was P0352 – Powertrain Ignition Coil “B” Primary/Secondary Circuit, which was the new coil pack.
It was a brief series of misfires (<1 s) and then it was running fine. I deleted the error code and took it for a few test drives and restarted it loads of times and there has been no misfiring.

Am I kidding myself to think that the brief misfire and error code following install of the new coil could just be the plugs burning off some crud as those cylinders were not firing the last time the engine was running when the bad coil was in place?

 

[koalar]

Well done in swapping the coil and finding the fault


But nope

The main cause of coils failing is a fault in the HT side

If the high tension voltage can not find an easy path to ground, it tunnels is way back through the coil, destroying itself

9 times 10 it a spark plug left in past it's serviced life, but fault HT leads also fail

 

[DTanner]

Thanks @koalar.
A Coil is only £14 at GSF car parts so I replaced both and am doing the spark plugs too.
Thanks. Will let you know how things go.

 

[DrPanda]

Hi gang, my 2p; and my fix.

Same fault logged on my cherished 08 1.1 (albeit coil 2), with random misfire.
Replaced, in this order, both coils at same time; check 1 year plugs( found ok) and replaced HT leads. Replaced downstream O2 sensor; ( fault possibly caused by misfire), also replaced battery as voltage faults logged via MES.
Checked and treated ECM plug with electrical cleaner; misfire would go away for about 2 or 3 drive cycles. but would return; plug and connectors are mint. Ordered virgin ECM from Ebay. Installed and cleared codes. No coding needed. Completed 50 miles since. all ok.

The caveat is the used ECM was same vintage so fault may occur on new ECM also; so i am keeping the old one and if required, send it away for repair.

Total cost until now, under £200 including battery.

Still curious how spraying the ECM plug would cure misfire? even if temporarily. But allowed me to confirm fault was within ECM PCB.

Love my Panda, treated it with 2 tyres.

 

[DTanner]

All seems fine now. Have put around 150 miles on the car since the coil and plug updates and all seems fine. In fact the engine feels very smooth with the new plugs. Will post in the future if this changes, otherwise considered this issue resolved.

Thanks for the help!


@DrPanda, that is a lot of work but £200 does not seem too bad if your car is back on the road again. The diagnostics worked well for me on this issue but it can be more challenging depending on the nature of the issue. I have never been so happy for the car to throw an error code as the one that confirmed the coil pack issue.
I will say that I have encountered issues that have improved if I dissemble and reassembly, to try and diagnose and don't even changing anything. But those issues tend to remerge. There are examples on the forum of people facing issues with connectors.

Still curious how spraying the ECM plug would cure misfire?

I can think of reasons that this can be true, but they do not mean that they apply to you. Careful diagnostics is what is needed. However, for example, corrosion/dirt/grime on the connector pins can cause the resistance of the connection to change and lead to changes in how the circuitry is controlled or driven. Spraying can help clean-up the pin so a good contact is made. On my car the pins have always looked pretty spotless, but I always wrap them (in like clingfilm) when they are disconnected so they do not pick up anything when I am working on the car.