I always hated working on exhaust.

 

I went back out and put a C clamp on the pipe where it came off the Y. Whacked it with a hammer a few times. It did not move. I slid back to under the CAT and grabbed it with both hands again and it came free. I cut it poorly with a grinder cutting blade. the CAT was fine. connected the pipes with pipe repair stuff and put it back in sans CAT. The truck still runs like crap and dies. It sounded like it was sucking or blowing air near the TB, maybe below it. It took a lot more out of me than I expected. I'm done for the day. the MT2500 did not tell me much except no codes. I'm going to climb on top and look down the throttle body and check the injectors are fully seated. Can't imagine how one wold pop out but?
Maybe something will come to me in my sleep. I think I have been getting signs of this problem coming on for months when it started. It would lope and take a bit to start revving up to normal rpms. It always registered low on the tac. The distributor is only a couple years old. Very low miles. I've only put 33K on it since I bought it. It is at 173266. All sensors new since I bought it. Maybe do another compression test. Could this be the computer going bad?

 

Entirely possible. The PCM does have quite a few years on it.....

Will your scanner do graphing? If so, how many sensors?

 

The PCM is new to me reman 7-20-21 Rock Auto
The MT2500 reads stuff that didn't show me any problems. I wasn't using the manual, I usually have to have it in hand and go step by step.
It does a test on activating all sensors and relays. It can do some one at a time. I was able to run it and I heard all the clicks. It did not indicate anything was wrong with them. I have no idea if that means they are working.

 

A fair few sensors won't set a code unless they fail completely, or, in such a way that gives readings the computer can't understand..... Being able to graph the data, lets you compare what is going to, to what the PCM is seeing. All it takes is one sensor to give slightly wrong readings, and the engine runs like crap. Figgering out WHICH one it is though, that's the fun part. Another fun part is, these trucks just don't like aftermarket sensors. They *may* tolerate some, but, the cheap fellers? (duralast....) Nope. They tend to introduce more problems than they solve.

 

The crank sensor is Mopar. The temp sensors were Advanced auto or RA and the plate in the dist is Napa and the map and IAc are napa too. I do not recall what the TPS is. Probably Napa. Dist is newish from RA. I just tightened the cap. Apparently the far side screw was not all the way in.
So I slowed down. I've started it a couple times. It was bad yesterday I only tried once. Today I jiggled the harness and hit the computer with my hand. it ran longer then died. Each time I restarted it quit faster. There is a giant sucking sound I have never heard before this, coming from the TB. I sprayed cleaner around outside the TB and got no reaction.There is no oil on the plenum. Last time it quit a puff of what must be fuel or smoke came out of the TB with force. That sound might be something blowing back into the manifold??
I think I just moved too fast on that CAT thing and it is probably valves. But I am guessing I ave never gone that deep into a motor.

 

What you are hearing is the IAC trying to get enough air to the engine. That isn't abnormal. Have you replaced the PCM? (I don't recall.... I read too many threads. ) If you have, where did you get it from?

 

I never heard the IAC make that noise before.
New to me PCM June 10, 2021 RA I checked earlier it is out of warranty.

OK this may be new hopeful info.
I wanted to move the truck to the backyard. it struggled to start since I tried earlier. I had not disconnected the battery and I got it backed up about 10 ft before it died. Then it did not want to start. I disconnected the battery for a few minutes and it started. I got halfway through the gate and it died. Again I had to disconnect the battery to get it to start. It is in the back now.

Does it starting after I purge the PCM by disconnecting the battery say the problem is PCM or is it something to do with one of the sensors telling the PCM what is going on???
Cannot find the PCM and how to check it in the FSM?

 

The sensors are all dependent on the PCM, resetting sensors does nothing..... I think the PCM is failing....

 

OK then. Now to find one cheap