you dont have to touch the distributer to pull the intake off,i think id defininatly fix the plenum 1st then go from there,im surprized you dont have a random missfire code...

 

I guess I should have looked at it a little bit closer before asking about the distributor. LOL


OK....Over the weekend I tore it down and replaced the plenum plate plus all of the associated gaskets. I also replaced the thermostat and bypass hose. It wasn't as hard as I was expecting it to be. Just time consuming because you have to move a lot of stuff out of the way to get to the intake manifold. I took pictures as I went and wrote down everything in sequence as I removed it. I figured that if I did it that way, I wouldn't run the risk of forgetting anything during re-assembly. It's a good thing I decided to do this job because it WAS leaking. The inside of the plenum was all wet looking from being coated with engine oil.
Now the unfortunate thing.....After doing all of this (which it needed very much) the truck doesn't run any better than it did before I started. But at least I can cross this off my list of things that might be making it run bad. Eliminate one thing at a time, I guess.
Oh, and one other thing, to anyone thinking of taking on this same project with the plenum plate, I strongly suggest that you go ahead and change the thermostat and bypass hose while you have everything apart....especially the bypass hose because you can't access it without removing the A/C compressor, generator, and the accessory bracket they are both bolted to.

 

Take it out on a long run and get it hot it may clear up

Reset the computer also

worth a try

your valves may be very dirty covered in oil your O2's may need to be burned off also.

Run a can of cleaner through it a full tank or two

 

Sounds like some good advice, but what do you mean about resetting the computer? If you mean erasing DTC's, It doesn't have any and never has.


I'm considering changing the Y-pipe exhaust (with the mini cats) and putting all new, fresh O2sensors in it. I've been suspecting that from the get-go and some scan tool Mode $06 information is indicating that it could be an issue along with EVAP probs. The weird thing is that I never get any DTC's. I know the MIL is functional so it isn't a burned out bulb.

 

Reset the computer the PCM it puts it back in start mode clean mode or whatever they call it.

How unplug the Neg battery terminal for around 10 minutes re hook it off you go its reset.

 

you said you replaced the crank sensor? what did it look like???reason I ask is I just went through an issue with my flexplate(reluctor for CPS)were one of the windows outside the ring was buggered up do to me using those windows with a screwdriver to help rotate the engine(this can happen very easy)..basically one of those windows was rubbing my CPS and caused all kinds of funny things to happen to the way the engine ran...this may be a long shot,but,possibly worth looking into..

 

When I replaced the CKP sensor, it looked old and dirty but there was nothing abnormal looking about it. The grommet that goes around it was a little bit misshapen due to it being improperly installed but I SERIOUSLY doubt it had any effect on the sensor because the sensor will bolt into place in only one position. The grommet is only there to keep contaminants out of that area. (water, dirt, etc.)

 

I had the battery disconnected while I was servicing the intake manifold. It should have started "clean" after the repairs. I have one more thing I'm going to take a look at today...maybe I'll get lucky. :-)

 

It has been a long while since I've posted on this thread so I'm going to revive it and add some new information.
I have completely replace the exhaust system...catalytic converters, O2 sensors, muffler and associated plumbing.
I noticed something unusual when I had my scan tool plugged in a short while back. After running the engine to operating temperature, I would shut it off and let it sit for about 15-20 minutes. Upon re-start and watching the engine data in real time, the engine would be in open loop for about 10 seconds then go to closed loop. Upon going closed loop, the Short Term Fuel Trim percentage in both banks would drop like a rock and bottom out at -36.3% causing the engine to idle rough. If I was to try to drive the truck at this point, it would backfire through the throttle body. If I sat and watched the data, after about 45-60 seconds the STFT(%) values in both banks would start to rise until they were at normal values. During this time I could feel and hear the engine idle starting to smooth out. Then I could put it in gear and drive away with NO backfiring and it would run great.
What would cause the STFT percentages to drop like that and stay there for that length of time? If I can just figure this out and correct it, I'll be a happy camper.
I've had the truck to an independent shop and also a Chrysler dealership (before I saw what I just mentioned above) and neither could figure out the problem.

 

What brand of O2 sensors did you use if Bosch that could be the problem many people complain about them causing poor running