JGillespy

Hello,
New to the forum but thought I would try and get some help regarding a misfire coming from 3 and 4 on my 06 mustang GT. This problem had started occurring after replacing the spark plugs, boots, IMRC plates and gasket. I just replaced the COPs on those two as well and the problem still occurs on a hard pull. I have JLT cold air intake on the car as well as a GT500 throttle body, the MAF is also after market as well, but is clean. I'm wondering if because the car is not tuned maybe that's why it is occurring or fearing a bigger issue.

66and06stangs

Can you switch a COP with a good firing cylinder to see if the COP is simply bad? Also, what kind of spark plugs? Did you use the stock ones that can break off or did you go with the newer design? It seems strange with just 2 cylinders misfiring...

JGillespy

I just replaced the COPs with new ones so I know that's not it

danzcool

I'd say do a compression test to verify you don't have issues with the cylinders. Beyond that it could be fuel injectors, but if it's not been tuned, I'd definitely get that taken care of, the tuning shop can probably shed some light on the problem.

JGillespy

All parameters were sat when we checked them so that's the only thing I can think of that could be causing that misfire my only thing was is that I'm only getting the code from those two cylinders

Derf00

So you're running a JLT intake and GT500 TB without a tune? Get it tuned first, then try to source any problems. Otherwise you'll just be chasing your tail right out of the gate.