It's my first post here and it's because I really need some help here. Original owner has worked on this Durango for over a year, I've been working on it since July, it's been to the shop for 2 of those months, and still I'm ready to set it on fire.


A little about the vehicle:
1999 Dodge Durango (Not sure of the package, has leather, heated seats, no sunroof, most of the bells and whistles).
143,000 Miles
5.9L
Automatic
4x4


I bought this Durango from someone that had given up. They had replaced computer, MAP, IAT, TPS, IAC, Crank Position Sensor, Water Temp Sensor, Oil Pressure Sensor, and replaced battery lugs. Finally he had a rod let loose during the testing and destroyed the engine. I bought it with the understanding that all sensors had been replaced and it's still giving issues with oil pressure dropping to 0.


I bought it in July, replaced the engine, started with rough idle, check engine on, oil pressure continuously dropping to 0. Replaced oil with castrol high mileage and the oil pressure drop stopped. Then the fun begins

Check Engine Light Codes: TPS Range Performance, IAT High



So I unhooked the battery, turn key on for 15 minutes to reset computer, go through the TPS setup with the accelerator pedal.
EVERY TIME, it idles rough and high up to 2,000 RPM, then the check engine light comes on and it idles right where it should at what appears to be 750 on the tach.


What I know:

If its cold, the IAT with throw the CEL (Check Engine Light).
If I drive it, and get the engine to temperature, I can knock out the CEL and it for the most part acts normal, but the oil pressure starts dropping, if at idle.
After its to temperature, and I let it sit for a while, it will start acting stupid again. (Appears to be temperature related)

Since I've owned it, I too have replaced sensors. (I have lots of used Dodge/Jeep sensors). I have put on a new and used TPS, no change. 2 used MAP, no change. New and used IAC, the new IAC worked for a few hours, then back to normal, this was also at the time when the CEL was showing IAC codes. 3 new IATs, and each time the IAT code goes away, for a few hours, then it comes back, and no change in performance throughout.


I took it to a real mechanic, who replaced the IAT, and TPS, and got it running normal, but would still occasionally throw out the IAT code again. Placed jumper on the IAT harness, it kept it off but idled rough. At this point we were thinking the harness, so I brought the Durango home.


NOW: (December)

Bypassed the wiring harness with new wires soldered directly to the IAT, and straight to the PCM (2" behind the connector). No change.

Still to this day, starts, rough idle, CEL comes on, idles fine, drives fine but will shut down (Replaced the Auto Shutdown Relay, no change), gets warm, CEL stays off, drives as it should, cools off, pain starts over.



CONCLUSION (Without resolution).

* If my sensors are now bad again, somethings killing them.
* If the computer is bad again, why was there no change between the original computer, and new computer, and it appears to work once up to temp (Can the water temp circuit be causing this?)
* The common theme with all these code is SENSOR GROUND (TPS, MAP, IAC, IAT, Battery Temp, Trans Temp, Water Temp, Oil Pressure, all have common sensor ground at PCM)


What would you do, prior to parting it out, or driving it off a cliff .

Thank you for your help in advance. I have been scouting multiple forums since July and have yet to run across one this extreme, or the problem solved that fixed my issue.

 

since you determined that they all share a ground i would be checking the ground connection for all the sensors, and the connections at the PCM, it sounds like that would be the source of the problem, a loose or dirty/corroded ground.

 

I haven't gave up on this thing yet, I did find a loose ground on the front of the engine, and it ran "better" for a little while, however, but it quickly went back to its old ways.

Still no go, have tracked down all other grounds, loosened and retightened..

 

I could see a temperature sensor making it run rough, but I wouldn't think it would actually kill the engine. From what I've seen, if you have an engine that shuts off while you're driving or once it warms up, it's either the PCM or the crankshaft position sensor.

 

Checking grounds should go beyond cleaning and tightening connections. After all the connections are good and clean, check the resistance back to the battery negative post while flexing the cable. The problem could be caused by corrosion inside the cable. I just had to replace one of the ground wires to my battery caused by damage you could not see.