Hello everyone I'm new to this. I'm wondering if someone can help me narrow down the issue I'm having with my 97 gt. I'm misfiring through cylinder 4 and narrowed it down to either bent valve, piston rings/ bottom end. Or maybe even timing. What test can I perform to narrow it down. And the mustang is completely stock.

 

Compression test results. Cylinder1 117 cylinder2 125 cylinder3 120 cylinder4 129 cylinder 120 cylinder6 125 cylinder7 125 cylinder8 125. Is there something off with these numbers? Haha

 

Those numbers sound fine

 

Move the plug/wire to another cylinder. If the misfire follows to the other cylinder then it's plug/wire issue.

 

I did that and the misfire stayed in the same cylinder. I even changed the fuel injector with a known good one. And still the issue is still there. I check fuel pressure and I got these numbers. 32psi at idle with near full throttle psi jumped to 39psi and fell to 32 while on throttle. Seems like a weak pump. Any input?

 

weak pump would cause multiple misfires, not one cylinder only. If you have compression, spark, and fuel, all at the right time, you either have a serious vacuum leak at that cylinder (intake manifold) or the cam could be wiped out, not allowing the valves to open properly. Spray some carb cleaner around the base of the intake on that cylinder, if it doesnt change the way it idles then pull the valve cover and inspect components

 

Definitely agree with WhiteFoxGT .... New to the forum as well but make sure you are getting voltage from the coil. I know its a long shot but the individual coil post could be faulty. Also, check voltage on the injector harness it could be something down stream that is causing the injector not to function.

 

dont hold your breathe for a response, 9/10 times they never come back to confirm a fix or issue

 

can anyone tell me what # these are they are suppose to be replacements for a 03 cobra supercharged
they are available from napa part #crb 218294 i just need to know if they are 39#