I have a 2003 4X4 with 4.7. Had a code 302 awhile back, reset it and then just read 441, 300 & 302. Rough idle at first but then seems to run fine. Drove back form Autozone after resetting and the light did not come back on. Seems to happen when cold and I think it is at low engine rpm. My gas mileage is fine, but I seem to feel a miss at low throttle. Any help is welcome

 

P0300 Multiple Cylinder Misfire
P0302 Cylinder #2 Misfire
P0441 Evap Purge Flow Monitor

I would start by replacing the plugs. Plugs are cheap and if you are going to pull them to inspect them you might as well replace them. Check your plug wires, cap, and rotor for corrosion as well. If you find any replace the part.

I am not certain about the evap code but after the tune up you can reset the codes and see if it comes back.

There are quite a few things that can cause a misfire but fouled plugs is the most common issue.

 

plugs were replaced by the dealer about a month ago. Had an over heat issue and had them replace the plugs because at 100K.

 

It is either fuel, air, compression, or spark.

Get a compression tester. Ideally you will be at around 100-110 psi at each cylinder and all cylinders should be within + or - 5 psi of each other. Another possibility is a dead injector. IIRC each injector should be around 12-13 ohms of resistance and should all be around the same resistance. Get a cheap multimeter and check out the electrical diagnoosis and testing sticky to learn how to use it.

Low compression can indicate a blown head gasket, cracked head, cracked block, worn rings or valves not fully seating. Check it out and let us know what you find or at least be a little better educated when you take it to a shop.

I just realized you have a 4.7 so nevermind checking wires, cap, and rotor.

 

What plugs did you install and did you gap them?


This brings me to my next question, you overheated the motor? How hot?

 

The plugs were replaced at the dealer. The overheat was happening during hot conditions at idle. Never for very long as it came back to the normal range. Replaced the fan clutch.

 

How about the efan? Did you have them check that out?

 

+1 Dan!


Also the stumble could be a sticky injector so run a bottle of SeaFoam through it, even though I don't like any additives it might help?

 

efan is OK and no more overheat issues.

 

Drove it to work this morning after sitting the entire weekend. Idled rough and got an engine light with trouble code 302.