Technical Was it the ignition coil or a bad spark plug wire that was causing severe ignition problems on my Fiat Punto Evo? Please read description

[nikolacvetanovski1996]

Can a spark plug wire get loose over time (losing contact with the spark plug or ignition coil) and cause severe ignition problems which will go away without the mechanic replacing them, just by reattaching them?

I’m asking because after the mechanic replaced the ignition coil on my FIAT Punto Evo the problem was gone. But, while he was replacing the ignition coil he said that he could barely attach the spark plug wire to the ignition coil, but that it was fine after he managed to do that. I asked him if the spark plug wires were bad and he said definitely no (I replaced them before 15.000 km). I’m wondering that maybe the old ignition coil is good and was replaced in vain. Can you please help me with an answer? The ignition coil was around for 62.000 km by the was and the car was driven mostly on LPG.

 

[bugsymike]

Just curious, what do you think was wrong with the previous reply you got in earlier thread with same question?

 

[nikolacvetanovski1996]

To be sincere, I suspect that I didn't compose the question correctly and that's why I didn't get an adequate answer to what I wanted to ask. In fact, with this post I wanted to provide more details that would help me to get a right answer and what I'm asking for is not an advice whether I should replace the ignition coil. In fact, my mechanic had already replaced them and I regret that I didn't learn in my life to replace it myself so I would've been able to now mount the old ignition coil back and test if it was really the culprit for the problems I faced or the old part is in a good condition so I don't need to properly dispose it, but sell it/donate it as an functional old part and change the mechanic forever.

So, to be more precise, I'm not asking for an advice whether I should replace the ignition coil with a new one and fix the car by that. My car is already fixed. What I'm asking for is a concrete answer concerning whether there is a possibility that the old part was not bad at all, BASED ON THE PROVIDED DETAILS, so I need to consider selling it/donating it as an old part and changing the mechanic that maintains my car in order to prevent this from happening in the future.

Disclaimer: It's not all about the money. As an IT engineer I cannot complain about my financial situation, but what I'm thinking about is my impact to THE ENVIRONMENT, as an end customer. Seems like no one else is thinking about that... Everyone else cares only if the car will be fixed and in my opinion, a good mechanic is not one that will fix the car (since there is no car that cannot be fixed), but to find the exact cause of the problem and fix the car by not replacing parts that are functional, just to make sure that that part was not the root cause. I would pay for a mechanic like that much more than I paid for the mechanic that replaced the ignition coil with a new one and the ignition coil itself, in total.

 

[bugsymike]

Thanks for clearing up the confusion.
Basically if you inspect the area around the coil pack where the HT ignition leads are fitted, if there is damage due to a poor connection in the past as I mentioned in your original posting I would expect to see "tracking " lines, a little like a lightning strike or like a crack on examining that area, it may not be very much , but with high voltage electricity even a little damage is enough to create a path for it to short out causing an intermittent misfire. This can be worse if it is dirty or on a damp day.
Something I also mentioned in my reply to your original post was that if the plug leads are pulled by the wire rather than carefully near the terminal as they are made of carbon string it is quite easy to damage them, this causes a break inside the rubber covering and until under load may not be noticed as the HT spark can jump the gap inside the broken wire
This knowledge is based on practical hands on experience over more than fifty years in the motor trade repairing cars.

 

[nikolacvetanovski1996]

Ok, so after the examination there are not cracks on the ignition coil, which looks similar like this one:

Knowing that:
1. The old ignition coil does not have visible cracks
2. The spark plug wires also look good (externally)
3. The spark plug wires were used for only 15.000 km (I bought them 2 years ago)
4. Replacing this ignition coil in the picture solved the issue with the misfiring in the 4th cylinder (illuminating the Check engine light and showing error code P0300 and P0304) and the car now works fine for 200 km,

is there still a chance that one of the spark plug wires was loose or not well connected, so it was losing connection with the ignition coil and it was the reconnecting of that spark plug wire to the ignition coil that solved the issue, not the new ignition coil? I’m suspecting this since the mechanic told me that he roughly managed to connect one of the wires to the ignition coil. I asked him if the wires were bad and needed to be replaced and he told me that the wires were in a perfect condition and did not need to be replaced. If my suspicion is correct and the old ignition coil was bad, then I want to sell or donate it to someone who needs it and not to pollute the environment by disposing or recycling it, since nothing is still 100% recyclable.

I suppose that now I provided enough data so I can get the correct answer. I also accept answers in the format: “I cannot tell for sure, but from my experience I strongly suppose that it was…” so I would appreciate you to tell me what your experience says about this, since it will be very helpful for me, although this is irrelevant for nearly anyone else on this planet, since I can conclude that no one else wants to bother with an car issue that has the status of “resolved”

 

[bugsymike]

In my experience , it is still possible to have a faulty coil pack with no external visible faults, tracking etc. due to an internal issue, in fact I have seen this on a few Citroen's over the years. On these they have no HT leads the coil pack sits directly above the spark plugs, like the photo below.
In general if no tracking visible then for a spark plug lead to be the problem it would have to be away from the coil, possibly 1cm, as I have seen a spark jump that much of a gap.
Going back to your query on the spare coil pack, the only way to prove the point would be for you to swap it back to test.

 

[nikolacvetanovski1996]

Nearly every mechanic will think that I’m crazy if I demand that from him. I don’t know how to replace the ignition coil myself anyway. I don’t have the necessary tools to open the engine cover and access the ignition coil. Anyway, assuming the replacing of the ignition coil solved the issue, I think that I should however trust the mechanic that did that… Thank you very much for your response

 

[nikolacvetanovski1996]

Hello bugsymike,

I want to inform you that I bought the necessary tools and watched a video on youtube that helped me to learn how to replace the ignition coil. Here’s what I’ve done so far. I deinstalled the new ignition coil and installed the old one. The car was working fine for 3 kms and then it started misfiring again, the same way as it did before (accompanied by rough idle and backfiring). I parked the car and waited for the engine to cool down (for about 2-3 hours). Then I deinstalled the old ignition coil and reinstalled the new one again. The engine now works completely fine.

So, I summarize that now to ask any more questions concerning the functionality of the old ignition coil is redundant, since this experiment proves that the old ignition coil was really the cause for the misfiring of the 4th cylinder. As I could conclude, each of the wires was attached to the ignition coil in the same manner and when I was deinstalling the old ignition coil, I realized that all of the wires were well connected to the ignition coil, so they were not losing connection anywhere.

I just cannot understand how the ignition coil worked fine for 3 km, then started with the problems again. Why didn’t it started immediately. Anyway, now everything is clear. I wrote this reply in order to help someone in the future if he/she is facing the same issue and is curious.

 

[bugsymike]

Heat plays a big part in why it worked for the first 3km.
You have now gained more knowledge of your car and it may help in the future should you wish to do repairs.
Also you can now have faith in your mechanic as he made the correct diagnosis.

 

[nikolacvetanovski1996]

Yes, now I have much more trust to my mechanics than before, since my suspicion was wrong. Thank you very much for all of the information that you provided me with, which helped me clarify the things that were bothering me.