Misfire

[Maine Ranger]

Hi Rangers
Im having an issue with my # 3 Cylinder misfiring ..Changed the pack and plugs ..I recently did a tune up on it and after that she started missing ..I coded it and it said misfire in cyl #3 it also had an engine light and on the dash it said my cap was loose although i bought a new cap yada yada still had a evap issue ..Question would the Evap cause a misfire in #3 or would it be fuel injection ???? shes a great truck and dont want her takin a crap on me ...need some help


John

 

[Dirtman]

Evap system can't cause a single cylinder misfire.

Since you said you recently did a tune up, I'd suspect it's something to do with that. Did you gap the plugs properly? Did you replace the wires? Make sure the boots are seated correctly? What else did you do in this "tune up". Also worth swapping the coils around to see if the misfire moves to a different cylinder. Then you know you got a bad coil (I know you said it's new but getting bad electronic parts right out of the box is pretty common).

 

[fastpakr]

What engine is this so it can be moved to the correct forum?

 

[Maine Ranger]

I used iridium plugs never gapped them Said they was pre gapped ,,Haven t swapped wires yet but I will try tune up i changed plugs air cleaner just basic tune up .........

 

[rusty ol ranger]

Probably got a bad injector would be my guess.

Disable the ignition and crank it over, pull the plug and see if its dry or wet. If its wet pull another plug and compare wetness.

 

[Maine Ranger]

What engine is this so it can be moved to the correct forum?

its a 4,2 v6

 

[Maine Ranger]

What engine is this so it can be moved to the correct forum?

6 cylinder

 

[Maine Ranger]

I am just trying to find out if it is an exhaust issue that would cause a misfire

 

[Dirtman]

I am just trying to find out if it is an exhaust issue that would cause a misfire

No.

 

[Maine Ranger]

Update on misfire ,,I rechecked everything ,,,reset gap, refitted plugs, checked fuel injectors ,spark is ok ,,,but still a misfire . However it misses sometimes not all the time ..also found oil in my air cleaner pan not a lot but enough to notice and my throttle body is dirty ,,,Maybe an evap problem ..Before i noticed that my fuel cap light was on all the time and my coder said that I had a leak (large) sooo am i correct in stating that it maybe air issue

 

[rusty ol ranger]

Update on misfire ,,I rechecked everything ,,,reset gap, refitted plugs, checked fuel injectors ,spark is ok ,,,but still a misfire . However it misses sometimes not all the time ..also found oil in my air cleaner pan not a lot but enough to notice and my throttle body is dirty ,,,Maybe an evap problem ..Before i noticed that my fuel cap light was on all the time and my coder said that I had a leak (large) sooo am i correct in stating that it maybe air issue

Check compression.

 

[Dirtman]

If there's oil in the intake/throttle body your pcv valve is not working. What is the misfire code your getting? As I said you simply cannot get a single cylinder misfire from these issues, they would effect ALL cylinders. So you would have a p0300. You said it's a #3 misfire which would be a p0303.

 

[rusty ol ranger]

Would a PCV affect just one cylinder?

 

[Dirtman]

Nope... none of the evap or emissions stuff would. That's what I'm trying to explain to him. Single cylinder codes have to be something that ONLY effects one cylinder. Valves, compression, spark, or fuel injector.

The pcv system is unrelated but oil in the intake and throttle body is a clear symptom that the system has reversed because the valve is stuck.

 

[fastpakr]

If/when you clear the codes, does it always come back to the same code for a #3 misfire?