2000 GT misfire cylinder 3


New Member
Mar 23, 2021
Charleston, SC
Hey guys, been reading for years but this is my first time posting a question. My 2000 Mustang GT is giving me a code for miss fire on cylinder #3. Engine is a 2003 4.6 2V. No mods. The original coil pack for cylinder 3 was bad. Moved it to cylinder 1 and it coded for cylinder 1. Replaced all 8 coil packs. New spark plugs and boots. All motorcraft. The code for running lean on bank one went away. The cylinder 3 misfire code came back New lash adjusters. Cylinder 3 had a collapsed one. Car is getting bad fuel mileage and it smells like I have a bad cat. Could be fuel getting into the cat. Idles just below 1000 rpms but occasionally it drops to 500 rpms and tries to die. When driving; the car will be running great and out of nowhere, it cuts back. I lose power and then it shoots forward quickly. It does this during acceleration or just cruising at a constant speed. Also, oil pressure is good when running but gauge drops to 0 when idling. I'm using Casterol Synthetic blend. Will have to check the weight but I believe its 5W20.
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I would have your injectors cleaned. Injectorrx did mine and it was worth the money. I would have the battery and altenator tested and clean the positive and negative terminals. Oil pressure will increase as the rpms increase so no worries there. I would also replace your fuel filter.
Thank you OneSick99GT. I was thinking fuel injectors but wasn't sure if that would throw the misfire fault. I was thinking of new injectors. I believe the factory injectors are 19psi. Would 24 psi be to much? I am planning on going to flat head pistons, mild cams, and getting the heads worked. So I believe I will need bigger injectors. Is it to early to go with bigger ones? Or do I need to wait?
If you swap out to different injectors you will need a tune so the new injector slopes can be adjusted for the 24s. The stock 19s are good enough with what you want to do and your pcm can probably keep you running nice, even if it requires more fuel with your small mods you plan on doing. A tune will cost anywhere from 500 to 700 dollars. So just keep that in mind before changing your injectors. Your car won't run when you upgrade those injectors.so a tune will be mandatory.