It started with a check engine light that read Cylinder 8 misfire. The truck was still running fine at the time so i thought it was due to the rain. After it dried up the light went away. A few weeks later my engine started to run rough as if it were running out of gas(sputtering). Threw the code Cylinder 8 misfire. It seemed to only sputter in low rpms. I changed all of the spark plugs, rotor and cap since they needed to be changed anyways. Problem was still there but light went away. I checked my injectors and they are all fine, even used some gas additive injector cleaner. I checked my fuel pressure and it was also fine. After checking the injectors i got the codes p0202, p0204, p0206 and p0208 because those are the injectors i checked. A few days later i got the light checked again and it also had a cylinder 1 misfire code. Truck is still runnning rough especially in low rpms. It seems to be getting a little worse because now it backfires every once in a while.

The problem is still going on now for about 2 weeks, I had a reply to a previous thread that it was my crankshaft position sensor. I replaced that with a new one and the truck is still running rough. Im not sure what to do now. If anybody knows my problem please reply so i can either fix it or narrow it down to something else.

THANK YOU!

 

try changing your coolant sensor, throttle postion sensor and your Idle air control valve one at a time, and make sure you reset your PCM after each one. im currently experincing something similar. and the things youve done i havent yet, so maybe my progress will help you. also can you add your trucks info to your signature block so we know some more info like motor/trnsmission type/millage/1-2ton/3-4ton/etc

 

here comes the nastiest word on the forum: plenum..

the misfire is common with a blown plenum.. especially the corner cylinders.. the hesitation is likely pinging (pre-ignition)..

take your TB off, grab a flashlight and a mirror, and give it a good look around for oil.. read the plenum sticky..

 

i cant belive i didnt think plenum. if it is you can get a replacement plate off ebay for like 50 bucks. and drew please correct me if im wrong but i didnt think that a blown plenum could cause a funky idle?

 

What about the coil? since it is multiple cylinders...

 

because the PCM tells the coil when to charge up and when to fire. if it was the coil it would be random cylinders but sice its specific ones every time that rules out the coil. and the pcm know when to fire the coil via the CKPS so if its good then the pcm should be firing correctly, which means ignition is good to the output of the coil

 

could just as easily be the coil..

i went back to the stock coil after using a couple other coils/packs/ignitions.. i use the original coil that came on the rig.. it's pretty tough.. not to say they don't crap the sheets too, though..

the plenum is easy enough to check.. the ulterior motive is: you've got the TB off already, so why not clean the crap out of it? that eliminates the IAC in most cases.. you'll have to pull the vac line off the MAP, so yo can see if it's cracked at the same time.. basically, you'll be in the vicinity of several of the most likely culprits.. so, killing more than one bird, so to speak, comes to mind..

a blown plenum won't cause a funky idle.. it absolutely will though at 'low RPM's'.. the truck being under load at lower RPM's while accelerating is about the most evident place to feel pinging... there, and at cruising speed (low RPMs in o/d)

 

i stand corrected lol

 

you're right as rain.. in most regards.. it's been my experience that coils just up and go one day- they sputter and go in short order.. THEN, one day, with a horrible yellow accel coil, it felt JUST like pre-ignition- but it was the coil.. so, I learned that coils DON'T just up and go all the time, they create mysterious issues that drive you bonkers trying to locate.. especially when they are yellow..

OP: your coil wouldn't by chance be yellow would it?