P0304 misfire problem

01-04-2010, 09:06 PM
Hi guys, the other day I was driving home from work (2002 Rodeo 3.2L v6)and felt a vibration from the engine and it wanting to die at red lights. I scan the computer and got a p0304 code. I changed out the spark plugs, they were due anyway. Nothing abnormal on them other than old and worn. no help. So I swapped #2 + #4 coil pack and erased the code. This time I got a p0300 muti misfire code. When I swapped them back I got p0304. Do I have a dual failure going on here or am I missing something when I swapped the packs? Until the other day the truck ran smoothly.

01-05-2010, 10:50 AM
A mis-fire are also commonly caused by a leaking intake manifold gasket.

If you are the original owner with under 120k it is covered by the warranty.

01-05-2010, 12:58 PM
Not the orginal owner. How do I check for a intake leak?
Mozilla/4.1 (U; BREW 3.1.5; en-US; Teleca/Q05A/INT)

01-06-2010, 11:23 AM

01-06-2010, 01:00 PM
I have seen a plugged catalytic converter choke half an engine out causing random misfires, and $3.5k on a bad fuel filter causing the same type of symptoms.

Random misfiring:

Fuel - Filter, pump, injectors
Air - Filter, MAF/IACT sensors, unmetered Air leaks, a dirty throttle body.
Exhaust - Plugged or blocked catalytic converter.

1) Clean throttle body.
2) Clean MAF/IACT sensors.
3) New fuel + Air filter.
4) Have a back pressure test done on your cats.

A good coolant pressure test, and a smoke test should beable to find unmetered air leaks on the Intake.

01-07-2010, 07:18 PM
I thought about spraying starter fluid around the intake manifold. But then the 4+" of snow started coming down. After a not so quick drive to the dealership and $350 later the verdict is in. An unmetered air leak at the manifold gasket. Thanks guys for your input. As always you did put me on the right track for a fix.

Cat Fuzz
01-07-2010, 11:14 PM
I'm glad you didn't do the starting fluid. Could have had a nice flash fire on your hands.

Good to know you found the problem.

01-07-2010, 11:17 PM
I thought about making a smoke machine with a shop vac + smoke bomb!

Add your comment to this topic!