1999 f250 4x4 v10,cylinder misfire?

Question

number 3 cylinder misfire,plugs changed,coil packs switched,no difference,intake gaskets changed,problem gone for about an hour then turns on check engine light again.
any ideas,thanks

thanks for the details,we did try switching the coils from other cylinders but if the wires are broken then we will look there further.

Answer 1

Just checked the ASE database and the one thing that kept coming up was the injector, wiring harness broken, and bad plug boot. Things to check.

Good Luck and Merry Christmas

Answer 2

If problem was gone for an hour after the intake gasket was changed, then your on the right track, take a can of brake cleaner and spray vacaum lines and the intake gasket, if the idle increases there is a vacaum leak present, this will cause a misfire code, I have been a licensed auto mechanic for 12 years, good luck

Answer 3

Isn't it ironic the person that suggests taking your vehicle to a parts store like auto zone to have a vehicle diagnosed would suggest to replace spark plug wires on a vehicle that has individual coil packs and has no plug wires. Sounds like the intelligence of an auto zone employee. This is why you don't take your vehicle to a parts store for diagnosis. They have cheap code readers not computer scanners. It will tell you misfire cylinder#3 then your only option is to keep throwing parts at it. I think its time to let a professional auto technician diagnose your vehicle. I think it would have been cheaper.

Answer 4

whats the plug look like. Oil fowled? flooded. Maybe injector sticking open and flooding it. try new plug wire.. or switch for test

Answer 5

Fuel pressure up to par? What are the codes that the computer has stored? You may have to take this one to the dealership.