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misfiring

backinblackgtp

backinblackgtp

New member
I recently got my car tuned, put on a 3.5 pulley, had new MSD 8.5 wires, and brand new tr6 plugs gaped at .30. but for some reason between 7-11 pounds of boost. my car starts to misfiring and almost boggs down, the SES light flashes for a good 30 seconds. when i went back to where i got it tuned, he used the tuning software and i made the misfire happen, and he said it was misfiring (6th cylinder) he replaced the plug, and checked the wire, and that swapped the coils, to see if it was an issue with them. and it still did it. any idea what else to check?
 


Why a .030 gap? Thats pretty small unless your tossing nitrous threw it. Misfiring is probobly do to a crap tune, and those MSD wires are not helping. Whats the mod list, do you have a scan gauge. Im assuming stock manifolds due to the abnormally high boost levels

You coild switch a coil and swap a injector and see if the mis follows, but from the sound of it it sounds like a lean misfire. I had that issue on a ZZP tune I had.
 
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no, they guy who tuned has a scan gauge obviously. and i have, powerlog, intake, 3 inch dp. made 231fwhp oh a mustang dyno, 249 tq. 13* of timing. whats weird though is it peaked HP at like 4900 RMP which seems low.
 
and he said he gaped it a .30 because its the 6th plug, furthest away, longest wire, and right above the exhaust so it probably gets really hot.
 
Running 13 degrees of timing isnt good either. It can cause elevated Exhaust gas temps. Anyways id swap a coil and injector see if the mis follows. Cant help on the tune side if you dont have a way to log
 
why is 13* not good, what should i be looking for? and we swapped coils, didnt help, he said hes gonna try injectors, you really think it could be a bad injector? not getting enough fuel or something?
 


so how would i go about that, tell the guy tune it for less boost, more timing? or do i need to change my supercharger pulley... AGAIN
 
Well, It depends on what the 02's look like with fueling. But if you cant run more then 13 degrees timing with out knocking and 02's in the 920-960 range then your running to small a pulley
 
so i should start with that, and if that fixes is, great, if not, and i have more timing, and it still knocks, should i check into the injectors?
 
Id swap the injector first, and see if the misfire moves. You will need to be able to scan to see which is missing
 


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