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Misfire questions

N

Natas

New member
I recently bought a GTP and am currently modding it. I was doing a scan today with my aero gauge and noticed random misfires on 3 and 4. I didnt think much of it as I intended to change out the stock plugs that were in the car with copper autolite 105's gaped at .55. When I pulled the old plugs i noticed that the electrodes were extremely worn. "as if they had been in there for a very long time" i checked the gap on the plugs and they were at .65 on what was left on the rest of the electrode. a couple of them were a little over .65 so i figured that's where the misfires were coming from on the 4 and 3 cylinder. After the swap I had more misfires then before on all cylinders. The misfires are not noticeable to me but they do show up on the scan. my question is should i gap the plugs to .65 and see if that eliminates the misfires. also is it safe to gradually increase the gap on the front plugs and scan as i go till i get the misfires out because you all know how fun the back plugs are. Any advice in this matter would be great
 


When do you notice the misfires?

At idle?

When coasting? Or normal driving? And how many?

You could get some new wires aswell and clean the coils to try and rule things out.

And .055 gap is good, you dont want to go over .060.
 
I purchased wires with the plugs. they show up at idle when im scanning and only under a little throttle. its not many it will be 1 here one there. Its an 05 comp G not sure if that would make a difference in the trouble shooting. Its not throwing any codes btw.
 
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.055"-.060" should be fine. I dont think the plugs are the issue(opposed to what u took out)....but did you unplug the battery when u did the plug change? That may help the ignition/PCM learn the new plugs and wires a lil quicker. Push come to shove, just check the resistance from the coils to the plug themselves....maybe something is defective(even though its new)....but everything must be consistant with eachother, if not then you've found ya issue. If u have a scanner, start from the code your getting and go from there(make sure theres no Vacuum leaks either, they can cause a misfire too........
 
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