The Misfire Thread
Hi
Ever since i put the 4.0 in i have had a sort of rough, but just bairly rough idle and now im getting cyl 4 misfire code. Otherwise it runs great and i switched the plugs, wires and coil packs without any improvement. The plug is not fouling and i dont suspect heads, but idk where to look now. It runs great! Just keep getting this code. Oh... when it has the code present in the computer it starts up wierd like there isnt much umf to it when you start it in the morning.
cpk? Advice please?
Ever since i put the 4.0 in i have had a sort of rough, but just bairly rough idle and now im getting cyl 4 misfire code. Otherwise it runs great and i switched the plugs, wires and coil packs without any improvement. The plug is not fouling and i dont suspect heads, but idk where to look now. It runs great! Just keep getting this code. Oh... when it has the code present in the computer it starts up wierd like there isnt much umf to it when you start it in the morning.
cpk? Advice please?
Drifting
Joined: Aug 2014
Posts: 39
Likes: 0
From: Roseville, CA
I used the coil pack that i knew worked from the 4.6 i had in there. Im wondering if the flywheel for the 4.0 is telling the cpk sensor something the ecu from the 4.6 doesnt like. Is that an issue?
Does your check engine light flash?(catalyst damaging misfire) also what codes are you getting?
Only thing I can think of is if you didn't time the crankshaft and camshaft gears before putting on the chain. The two gears have arrows or markings that need to be aligned or timed. I bet you knew that and timed them correctly though.
If your coils are definitely working and no vacuum hoses are cracked and the pcv valve is fine the only thing I can think of is a clogged or stuck open injector.
Drifting
Joined: Aug 2014
Posts: 39
Likes: 0
From: Roseville, CA
I can't say that the vacuume hoses are fine, I haven't checked them. The coils are identical. I guess I should check vacuume or injector and check back. I had the plenum off for the coils and looked at the injector, but didn't swap it or anything. I did check them before putting it back together with a power probe and air compressor while doing the swap which was maybe 6k miles ago Jan 2016
I can't say that the vacuume hoses are fine, I haven't checked them. The coils are identical. I guess I should check vacuume or injector and check back. I had the plenum off for the coils and looked at the injector, but didn't swap it or anything. I did check them before putting it back together with a power probe and air compressor while doing the swap which was maybe 6k miles ago Jan 2016