IA_F150

Okay, thanks to ebxgsxr I purchased a code reader on eBay to help me figure out why my truck still has a miss. It was easy to use but the codes I received from it are troubling me.
I got:
P0301 - Cylinder 1 Misfire Detected
P0303 - Cylinder 3 Misfire Detected
P0308 - Cylinder 8 Misfire Detected

I have already changed the plugs, wires, and both coil packs. Please help. I am at a loss.

torkum

Something you can check is the fuel injectors. Number the injectors and swap the known bad cylinder with a known good one. For example, swap #1 injector with #2 injector and see if the misfire code changes to the #2 cylinder.
Have you changed the fuel filter or cleaned the MAF?

IA_F150

We will try that. The fuel filter has been changed. We have not yet cleaned the MAF. Can those items cause a misfire?

torkum

The MAF is a long shot but wont hurt. As for the injectors they can rust or have carbon build up that you will see when you remove them.

IA_F150

Can you clean the injectors or do they have to be replaced?

torkum

Go here for cleaning instructions: http://fordfuelinjection.com/?p=82

IA_F150

Quick question: Could a plugged cat possibly cause these codes? I have reason to believe it is plugged and plan to bore it out. (I know I'll need the MIL eliminators)

cole_ford

thats a good post. I will use that in the future. If your cats were bad, you would pull code that has something to do with them. I think

Try what Torkum says first, and if that doesnt help, try something else. But he has helped me with a lot.

andersen69

thats a very good post. i have also a P0308, and i tried to replace the coil with no effect, as Torkum says i swap injector cyl 8 and cyl 5 and now i got a P0305.
Thaks!

jsimmonsd

Hello,
I had a 303, checked all plugs and coils. looking like the cylinder is bad. I noticed my mechanic put 7 quarts of oil in and its only a 4.6. could the excess oil cause misfire, rough idle etc. Now everyone seems to think its a cylinder or vlave issue? it also seems a little suspect that a) the rough idle and power loss happened less than day after i got it back form the mechanic and b) my mechanic told me after i brought it back in he thinks its a carbon build up or dirty injector and to drive it another couple hundered miles and see if it clears up.

My neighborhood buddies (both competent mechanics) did some elimination work and say its a cylinder issue. gonna check compression soon. I 'm feeling something is fishy aobut my mechanics work....help... i am a carpenter not an engine guy.

sorry if I changed the thread too much.