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Technical Misfiring after changing plugs and leads [emoji30]

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Technical Misfiring after changing plugs and leads [emoji30]

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Daihandley88

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Changed my plugs and leads this morning ( haven't changed them in a while) and since then it's misfiring really badly. I have checked the leads are on tightly but I'm wondering if the coil pack is kapoot? The last time I changed the plugs and leads I had to replace the coil pack because of the same thing? Please help
 
Daihandley88 said:
Changed my plugs and leads this morning ( haven't changed them in a while) and since then it's misfiring really badly. I have checked the leads are on tightly but I'm wondering if the coil pack is kapoot? The last time I changed the plugs and leads I had to replace the coil pack because of the same thing? Please help
Click to expand...

Engine model?

Which cylinder is missfiring ?
Are the sparkplugs pregapped (original fiat) ?
 
It's the 1.2 8v engine. Not to sure on which cylinder as yet because the hand held obd reader will work on any car except mine for some reason. The new plugs are denso make xu22epr-u (not sure what pregapped means sorry) same as the last set I put on it.
 
Was the car misfiring before you did the work? If so, then yes, it might be the coil. I had a similar situation on my daughter's 8 Valve 1.2. I prefer NGK spark plugs, but any make should work if new. Are they definitely the right ones for the car? Note that if the gap is too large, the coil will struggle to fire them. As Arthur says, it's easy to get two of the leads the wrong way round. Also make sure that the new leads have gone fully down on to the tops of the plugs, new ones can be a bit tight.
 
Avocet said:
Was the car misfiring before you did the work? If so, then yes, it might be the coil. I had a similar situation on my daughter's 8 Valve 1.2. I prefer NGK spark plugs, but any make should work if new. Are they definitely the right ones for the car? Note that if the gap is too large, the coil will struggle to fire them. As Arthur says, it's easy to get two of the leads the wrong way round. Also make sure that the new leads have gone fully down on to the tops of the plugs, new ones can be a bit tight.
Click to expand...



Thanks for your help! The plugs in using are denso xu22epr-u 3179. And the gap on them is 0.9 mm. I'm not sure what the gap is supposed to be and thought they would be pre gaped. All was fine ish before I changed them although every now and then it would have a little miss
 
Daihandley88 said:
Thanks for your help! The plugs in using are denso xu22epr-u 3179. And the gap on them is 0.9 mm. I'm not sure what the gap is supposed to be and thought they would be pre gaped. All was fine ish before I changed them although every now and then it would have a little miss
Click to expand...


If you've still got the old stuff available use them to try and diagnose what's wrong...presume everything was all OK before.
 
KenMavor said:
If you've still got the old stuff available use them to try and diagnose what's wrong...presume everything was all OK before.
Click to expand...
yeahthat.gif



Just because you have new parts does not mean they are OK. I've had a couple of instances of duff brand new plugs over the years.
 
I have just put all the old plugs and leads back on on no change, that's why I'm thinking coil pack is on its way out
 
Shouldn't the spark-plug gap be 0.7mm (as in my school time) ?

The bigger the gap the higher the voltage needed to create the spark, one of the coil may be already on its knees, thus the heratic firing-up.


Best regards, Bernie.

If somebody helped you here, click the thanks button, it costs nothing
 
Last edited:
I'm really not sure what it should be but I have ordered a new coil pack for it to see if that works! Thanks for the input Bernie I'll look further into the gap to see if it is 0.7mm because if it is then my plugs are way off
 
Clutching at straws now.You say that it has been a while since you changed the plugs and leads, so when did you last renewed the fuel filter? I appreciate that 95% of poor running of engines are electrical issues,but it is just possible that the fuel filter may be in need of replacement, as you said the car did misfire before. As I say just clutching at straws.
 
ArthurM said:
Clutching at straws now.You say that it has been a while since you changed the plugs and leads, so when did you last renewed the fuel filter? I appreciate that 95% of poor running of engines are electrical issues,but it is just possible that the fuel filter may be in need of replacement, as you said the car did misfire before. As I say just clutching at straws.
Click to expand...



Where about would I find the fuel filter? Didn't think there was one on there you can change, thought it was in the pump as a sealed unit
 
hi Daihandley Not having your make of car ,I do not know where or if there is a fuel filter. I am sure someone on the forum will know. I appreciate your dilemma and as I said I was clutching at straws
 
ArthurM said:
hi Daihandley Not having your make of car ,I do not know where or if there is a fuel filter. I am sure someone on the forum will know. I appreciate your dilemma and as I said I was clutching at straws
Click to expand...



Ok thank you very much for helping me anyway [emoji106]
 
Just a quick update for you! It was a faulty injector on cylinder 2. Not a fan of the £140 price tag for the 1 injector though but it is what it is. Thanks for everyone's help much appreciated [emoji106]
 
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