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Why The F#$K Am I Misfiring After New Coils?

SargeRX8

By SargeRX8,
in General Maintenance

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SargeRX8 Grand Master

SargeRX8

Posted
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I changed to set yellow jackets and my car is miss firing badly under boost. No matter what gear it misses. The car was perfect with stock coils. Easy driving does not cause any miss only hard driving. I noticed too the plugs look gapped down. I've got a brand new set of bcp7res11 to go in. should that cure the problem?

MrStabby Grand Master

MrStabby

Posted
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Did you change the plugs at the same time as the coils? If you put plugs in with a wider gap, that would explain it. Otherwise, check all the electrical connections are clean/tight.

FWIW the more boost you run, the harder it is for the spark to jump the gap. The smaller the gap the easier it is.

Why did you change if the stock ones worked?

SargeRX8 Grand Master

SargeRX8

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  • Author
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Stock ecu, 9psi boost exhaust fmic. Changed as I'm

upgrading turbo ecu injectors etc. I'm using the same old

plugs didn't change em. Pretty sure everything is tight. Could the shorter gap with these coils cause misfire? The only thing I changed is the coils and then the missing started.

MrStabby Grand Master

MrStabby

Posted
Posted

Stock ecu, 9psi boost exhaust fmic. Changed as I'm

upgrading turbo ecu injectors etc. I'm using the same old

plugs didn't change em. Pretty sure everything is tight. Could the shorter gap with these coils cause misfire?

Not sure what you mean by that question - the gap is the same since you didnt change the plugs right?

The only thing I changed is the coils and then the missing started.

Not a good sign, you may have a bad coil. Check the resistance of the primary winding on all six - it should be the same. The spec for the stockers is 0.6 to 0.9 ohms and the yellows should be very close to that, middle and left pin when looking at coil plug. The primary winding check can only confirm if its bad, not that its good.

EDIT: Sorry that spec is for external ignitor coils only. Since you're Series 2 you wont have an external ignitor and the spec/pins will be different. I'm guessing it will have 4 pins instead of 3?

SargeRX8 Grand Master

SargeRX8

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What is the point of upgrading them just to have problems? this is pretty bull. There are 3 pins ib g and a plus symbol.

what I meant by the gaps is the current old spark plugs are smaller gapped. the new plugs are 1.1. Would the new plugs and the bigger gap eliminate this? only other choice is change coil by coil...

SargeRX8 Grand Master

SargeRX8

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My old plugs are heat range 7 they were fine. My new plugs are identical to the old ones apart from the gap. 9psi. Its 100% related to coil/spark plug configuration. My old coils spark combination NEVER misfired. Only after installation of these coils did the car start misfiring.

DVS JEZ Grand Master

DVS JEZ

Posted
Posted

why did you change the coilpacks if you didnt have an issue?

does it feel like only 1 cylinder is misfiring or a few?

put the stock coilpacks in 1 at a time till you find the dud,

also don't rule out spark plugs just yet, check each one very closely for hairline cracks etc, also check the electrode condition/colour and see if there is 1 that is different.

SargeRX8 Grand Master

SargeRX8

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  • Author
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why did you change the coilpacks if you didnt have an issue?

does it feel like only 1 cylinder is misfiring or a few?

put the stock coilpacks in 1 at a time till you find the dud,

also don't rule out spark plugs just yet, check each one very closely for hairline cracks etc, also check the electrode condition/colour and see if there is 1 that is different.

Going to be running much more boost with the new turbo so(18psi) this is generally the first step as the old ones are going to be pretty tired when it comes to the increased load. I have no idea but it kind of comes in bursts of misfiring, not just one splutter but like splut splut splut splut. It feels like this video. Ive pulled them all out now, they were a factory second unit which I bought from performance wise and paul is more than happy to take them back and replace with a new set and test out the old ones. Just to ensure it is the coil packs, Ill be going out now for a drive with the old ones back in to see if it still does it. I doubt it will because I never had a single misfire whilst driving on my old coils. I checked all spark plugs except cylinder 4(under the crossover pipe, I'm lazy lol). They all looked near perfect for spark plugs of their age. I have started a thread a while ago asking people to check out the condition of my plugs. Very clean and healthy looking. They looked the same across the board(apart from 4, couldn't get to it).

Mine did exact same thing turned put to be dodgy boost t was over boosting.. Try turning boost down, is it happening at night / cooler weather?

I run a Greddy Profec B spec 2 boost controller. Haven't fiddled with the settings since its been fitted to the car. Happens any time. Happened last night coming back from work. Happened the other day driving to just jap(40 min drive so warm engine bay etc). Lets see what happens on the drive now. Maybe I did crack a spark plug when fitting it back in but I won't be able to cross anything out until I drive it now.

1:25 seconds sometimes it gets as bad as that and sometimes there is no break between the misses, it just keeps missing all the way.
SargeRX8 Grand Master

SargeRX8

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  • Author
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Took it for a drive, let it warm up properly. First gear all the way to 6500rpm, second gear to 6000rpm 3rd gear to 3000rpm, not a single miss. Using the same spark plugs, same boost, stock coils. I can go out now and test each coil, just by swapping one at a time with first and it will miss with the faulty one but there is no point. It is definitely the coils. Fit them in, they miss. Remove them, miss is gone.

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