2002 3.0 with a little over 100k. auto tranny

So i had noticed some worse than normal gas mileage, also its been idling a little rough sometimes. ive even caught it idling a little high sometimes. Ive been running on steelies recently, so i had been attributing the gas mileage to that. My comparison to how my truck normally feels is a little off because of the different rims/tires.

Well anyways i threw a check engine light yesterday morning. I kinda guessed it was my IAC valve or my Throttle position switch reading to low. which is a problem i have had before which went away with a little cleaning. I pulled the code and it was showing a cylinder 4 misfire.

I havent had any experience with misfires, but what do they feel like. ive noticed a rough idle sometimes, but not really any bucking or anything on the road. I cleared the code yesterday and it hasnt come back on yet (havent done too much driving though). How long would it take the code to show back up? if it doesnt show back up should i not worry about it?

Also i dont have my manual, so which cylinder is # 4 anyways.

Ive been searching and it seems like just about anything can cause this problem. what do you think?

Here is what i have come up with. whats a good order to do this, and which are a waste of time?

- Pull the plug and see how it looks
- vacuum leak maybe (how and where do i check for this)
- plugs and wires (replaced maybe 6k miles ago)
- coil pack?
- TPS sensor and IAC valve?
- clean out throttle body and MAF? (worth the time? cleaned TB not too long ago)




thanks,

Lee

 

hey i am having the same problem right now. from what i can tell the misfire just feels like the truck is hesitating real bad and kind of stumbly feeling. if i am sitting at a light and floor it, it revs but hesitates the whole way through the rpm range, its really annoying. the first time it happened i changed all the plugs and wires and it didnt help a week later it threw the code at me. i was going to change my coilpack but then it stopped "misfiring" for a week or two it ran great and then started doing it again, and now its been bad lately. i have tried water remover and that has done nothing, i think it has to be a vacuum leak. it has thrown 3 "misfire in cylinder 3 codes" i dont know what to do

oh yeah and i have a 2002 3.0l auto with about 95k miles on it

 

Go directly to cyl 4 and pull the plug.

1.) If it's wet, it's getting fuel but may not be getting a spark. Inspect the spark plug wire for cracks and cuts and also make sure it was secured to the coil and plug properly. If it's still acting up, chances are it's the coil pack.
I had this scenario last fall with my 6th cyl and it turned out to be the coil pack. Replaced it and all was well.

2.) If the plug is dry, it may not be getting fuel. Check your fuel injector for that cylinder.

I'm sure others will chime in on the "if it's dry" scenario. I'm not all that familiar with that as I've never had to cross that road yet.

 

thanks for the help. can anyone tell me which cylinder is #4

 

is it the driver side front cylinder?

 

Yes, #4 is driver's side front.

 

thanks. man i have no tools here at school anymore. need to go get a spark plug socket

 

Chris is right I would look at both the injector and the coilpack. If either one is bad it would cause that misfire issue right away. It can also be that the coil is only working sometimes so maybe that is why it is running ok then bad on and off.

Let us know how it turns out and what you find

 

good luck man let us know what you find

 

so ive been doing some running around and didnt have a chance to get to it today, but did a bunch of driving today and no trouble or light thrown up. could it just have been a fluke? or should i still check it all out

 

yeah i would check it out; however, you cant fix something thats not broken, so maybe wait for it to act up again? i drove around today and my truck felt great, light was still on, but right before i came home i could feel it start to hesitate again