I bought a 99 Durango SLT 5.9 that has 157000 miles on it. It had an aftermarket stereo, which really sounded good. I had to have a car and I got it for 800 dollars. It seemed like a good deal, and got me through a bad time. I really like the looks of it, and thought I had really sliced a fat hog on the ***. Only problem is, it looks like I am the fat hog, and my wallet is screaming like a stuck pig. It had been sitting for 8 months and it was running really rough. I figured how hard can getting it to run BE? Well, now, 2000 dollars and a hell of a lot of frustration, I am about out of ideas, and am out of ideas.

I have also posted this in Dodge Durang.net, but, I figure every little bit helps. The first issue was that the vehicle kept losing power and dying at random times, roughly every 20 miles or so. I had the "No Bus" issue. Got a new (well reman) PCM and it started to run better. It didnt lose power and die while driving. It then started running like crap, no real power etc, So, I went with a new MAP. It solved some more of the problem but it was still surging. I found that my voltage is erratic coming from the PCM to the TPS while the vehicle is running. So, I thought I would replace the TPS, That did little to solve the problem, and then I decided to get the IAC. Well, some more of the problem worked itself out, and I thought, Ok this is reliable now. In a day or so, the idle started surging by about 100 to 400 rpms and then dying. I replaced the battery at that point and as usual......NADA!!!!! Out of frustration, I took it to a mechanic. He reset the parameters and then shot the throttle body with some cleaner. It solved a bit more of the problem, but not all the way. I can take the thing on the road and it will die intermittently now, but its not nice and smooth on the ide, nor is it reliable. There has been an electrical burning smell and I cant see where it is coming from. To top all of this off, the rear windows wont roll down, and I am throwing NO codes, nothing is stored in the OBD and the reader doesnt pick anything up at all.

The goofy part is that there are some days when it runs like a new car. Nice smooth shifts, smooth as glass idle, like today. It was idling perfectly, right around 700 rpms, and as smooth as glass. I put it into drive, and the idle stayed the same. I drove out of the parking lot and the thing stalled. I started it and still the same idle. It would stall as soon as I took my foot off the accelerator, but if I kept a little pressure on it (the accelerator)when I stopped it would idle perfectly. That was the good part, and I was really excited as the rango has a lot of power and a really nice ride. I left a stoplight and had someone on my rump, so I had to gun it a bit. It acted like it didnt want to shift. I almost was at WOT when it finally did shift and then I noticed it went back to the high idle and not stalling. It jerked a bit and I was puzzled because normally the shift is pretty smooth, but it doesnt shift up and down what seems normally to me. If I go up a hill it shifts down and revs the rpms up to around 2000, then comes back down to around 1500 then back to 2000 then shifts to a normal range. The shift itself is smooth, and I dont have any worries about the tranny.So I guess here is my question, would the tranny shifting have anything to do with killing the truck if something is off? I still have no codes (I checked it when I got home). Anyway, any help would be appreciated. Thank yall its nice to meet you.

 

Was the throttle body cleaned of carbon in the iac port? This needs to be done because if there is carbon in it the the new iac will still not work correctly. It may be the iac itself, Some people have gone threw 3-4 of them before they find one that works. Do you have any vac leaks? Was the plenum gasket replaced?

 

I didnt get a really good clen out on it. Ill hit it again today. The IAC is good, I am not getting any codes from it, and generally speaking the throttle is good, so I am reasonably assured it is doing its job. Would you happen to have ground locations for the PCM, and sensors in the wiring harness? I wanted to to check for continuity, and make sure nothing is shorting.

 

the IAC only controls the idle, has little to no effect on throttle response, and if the port wasnt cleaned it can hang up on gunk in the hole, it is a very good fit since it controls airflow when the throttle plate is all the way closed.

the other question i am going to ask is what is the condition on the battery cables? are they corroded/dirty (what about inside the insulation?) i have seen cases where the cables were corroded internally creating resistance which lowered the voltage that was seen at the PCM which screwed up all the sensor voltags.

 

Thank you for the response. I have to do a clean out on the TB, and I was checking the battery cables and found that the negative doesnt tighten down all the way. I also saw that the Pos cable is basically brand new. The good news is that I had high idle this morning, but this afternoon it ran perfectly. So, I think I am getting somewhere. Does anyone have sensor grounding locations (ie Wiring harness for the PCM to the IAC, TPS, MAP, CPS, etc) so I can make sure I have good continuity and no breaks in the system? Thanks again.

 

The sensors get a ground and a 5 volt supply voltage from the pcm.

 

High idle can and usually does mean there is a vacuum leak. The extra air sneaks in, the PCM has no choice but to add fuel to keep air:fuel right, so it idles higher.