Car Feels like it misses under boost

layinthesmack31

Registered User
Hey guys well i am having some issues with the bird that when i get on it and it gets into boost it seems to buck a little like it has a miss. I have the mods listed below and i just dont know where to start. It has new iridium tipped plugs in it and i didnt get a chance to get new wires and they have been in there since i bought the car like 4 yrs ago. Keep in mind i only have driven it like 500 miles in the last 2 yrs so it hasnt got usd much. I just dont know what to check first. Its like it drives great just cruising around but after it warms up and u punch it it misses. So any info would be greatly appreciated. u guys have been awesome in the past. Thanks

Matt
 
Missing under boost is more than likely associated with plugs or wires. I chased a miss when boost would reach about 5 psi for a long time and I assumed the wires were good. They were aftermarket wires from a good well-known company with around 50,000 miles on them. Finally I changed them out with a set of stock Motorcraft wires. They solved the problem. Another thing, because of the tight spaces involved it is very easy to crack a plug on install without knowing it. Cracked porcelain will result in similiar missing. John
 
Well I am positive the plugs are ok since when i installed them the heads were off the car and had just been ported and polished. so i guess it must be the wires. they actually say motorcraft on them. I have no idea how old they are but i know before i bought it a remanufactured engine was put it so they would have put new wires on i think right? the engine has about 40000 miles on it so it is probly the wires. I would have put new ones on at the time i had the heads off but ran into a money situation and couldnt afford them. I will say though all this started after i put everything back togather. So could the new iridium tip plugs be causing wires that made good spark with motorcraft plugs to misfire or not get enough spark? thanks for the response.

Matt
 
I recently installed a set of new NkG Iridiums and got a missfire above 4000 rpm about a month or two later.
When I took them out the gap varied between .51 and .574. I think they were all gapped around .54 when I installed them.
I am guessing the iridium plugs are more sensative to gap then standard plugs.
My new spitfire plugs are .43 and no missfire now.
 
Back
Top