[DeadEndCustoms]

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.

 

[skitzo.d]

you said you replaced the battery lugs.. did the battery get checked out? was the PCM new when it was replaced? have you bypassed the common ground pin on the PCM plug? maybe it's the pin?

you put a new engine in... dumb thought but did you put a new oil pump on? what oil are you running?

 

[DeadEndCustoms]

you said you replaced the battery lugs.. did the battery get checked out? was the PCM new when it was replaced? have you bypassed the common ground pin on the PCM plug? maybe it's the pin?

you put a new engine in... dumb thought but did you put a new oil pump on? what oil are you running?

1) Battery checks out good, although I have not tried using a different battery (will do today).

2) The Replacement PCM was aftermarket new, and not from a salvage vehicle.

3) By common ground do you mean sensor ground? Either way, I have not bypass from the PCM. How would I do this? I'm thinking the PCM needs the feedback, I don't recall seeing continuity between the chassis and sensor ground.

4) Oil pump was from the replacement engine (2001 5.9 Ram). Had to replace the oil pan and cleaned/reused the pickup tube from the Durango. Using Castrol High Mileage. Having same issue between 2 oil pumps, 2 engines, 3 sensors, and 2 computers. I actually chased this problem down first, and ended up with the Castrol High mileage oill. I have not seen the oil pressure drop since August when it was replaced, until yesterday (12/1/15), and its pretty consistent again (after bypassing sensor wiring to the IAT.)


Additionally, all jumper connections I have performed are clean and soldered. Nothing is disconnected with battery connected and ignition switch on to bleed down.


I want to think its a ground issue, being that I have had codes from IAT, IAC, TPS, and the oil pressure dropping. They all share the sensor ground. Interesting enough though, the battery temp, trans temp, and water temp, also share this ground and I don't have any codes for them unless I remove the sensor ground from the PCM.

 

[Volphin]

Have you confirmed the oil pressure drop with a mechanical gauge? Or are you going by your dash? You may not be losing pressure at all and just need a new sending unit.

Now, on to your drivability issue. Are all ground straps in place and clean? What is the condition of the PCV valve? IAT sensors are very susceptible to damage during "cleaning". That sensor is suspect and it needs to be replaced, because it sounds like an aftermarket part. Never had any luck with those. The coolant sensor does indeed play a key role between open and closed loop running. Further, because of their location, they are easily damaged along with the harness connection.

I'd also be looking very closely at the fuel mapping signal sent from the upstream O2 sensor, and if possible, use a scan tool that allows you to monitor each system sensor in real time and capture the data.

Finally, why the hell are you using high mileage motor oil? All it has added to is a seal hardening additive. BAD JUJU. Use Mobil 1 or Valvoline full syn from Wally World.

HTH

V

 

[DeadEndCustoms]

Have you confirmed the oil pressure drop with a mechanical gauge? Or are you going by your dash? You may not be losing pressure at all and just need a new sending unit.

Now, on to your drivability issue. Are all ground straps in place and clean? What is the condition of the PCV valve? IAT sensors are very susceptible to damage during "cleaning". That sensor is suspect and it needs to be replaced, because it sounds like an aftermarket part. Never had any luck with those. The coolant sensor does indeed play a key role between open and closed loop running. Further, because of their location, they are easily damaged along with the harness connection.

I'd also be looking very closely at the fuel mapping signal sent from the upstream O2 sensor, and if possible, use a scan tool that allows you to monitor each system sensor in real time and capture the data.

Finally, why the hell are you using high mileage motor oil? All it has added to is a seal hardening additive. BAD JUJU. Use Mobil 1 or Valvoline full syn from Wally World.

HTH

V

* Oil pressure when hot gets to around 3-5PSI at idle, which is tripping the sensor, with standard oil. Did not use mechanical gauge after replacing with high mileage as the problem went away when switching for 5 months.
* As far as I know the ground straps are clean, definitely tight. I will revisit this. The only ground straps I took off and put back on were at the driver rear of the engine and passenger rear valve cover.
* PCV has been replaced, grommets too. So far a total of 3 PCV's have been used. Also for testing reasons the PCV was plugged, and the intake was capped, to which no noticable change whatsoever, essentially eliminating that as the problem, the PCV is also functional and the plugs/caps were removed and the PCV restored in case someone is wondering.
* I don't have the ability to map the sensors, I'll have to get a shop to do this. I saw a downstream O2 code a few months ago, this was replaced.

* The reason I'm using high mileage is because almost every thread online with oil pressure dropping on the 5.9 has suggestions and results for the high mileage oil. After it's had 3 sensors on it and a mechanical gauge, along with 2 oil pumps and clean pickup tube, and new oil pan, this actually worked and took that headache away for a while. Now its back, along with 2 other sensors that come and go with heat. I've got less than 50 miles on this thing since the engine was dropped in so whatever keeps the light off is one less thing, I'm not worried about the oil. The high mileage is synthetic blend. Usually introducing a full synthetic into an engine that has never ran it, along with high miles, results in leaking.

 

[tomk]

an old battery, even one that tests good, will cause all kinds of idle misbehavior. So definitely swap in a new battery, at least for several start/drive cycles.

make sure all the IAC passages are at least reasonably clean.. and be careful of the IAC motor pintle when you have it out, it is easy to screw it up (though it usually eventually fixes itself)

5psi at idle seems pretty low.. the min spec is 6PSI (which also seems low)

 

[Volphin]

Q: How many miles were on the donor engine?

Also, have you looked at the intake manifold through the TB for oil? The plenum gasket can leak and cause drivability issues as well as oil consumption. Was this swapped at install or did the donor come complete?

PS: That is a wives tale about syn motor oil. The reason your issue went away is likely because was there was a spot of sludge plugging the sensor and it has worked free. I'd still confirm.

 

[DeadEndCustoms]

Q: How many miles were on the donor engine?

Also, have you looked at the intake manifold through the TB for oil? The plenum gasket can leak and cause drivability issues as well as oil consumption. Was this swapped at install or did the donor come complete?

PS: That is a wives tale about syn motor oil. The reason your issue went away is likely because was there was a spot of sludge plugging the sensor and it has worked free. I'd still confirm.

Yeah, i've swapped throttle bodies, looked inside the plenum, a little wet but nothing extreme. It came assembled. I have all same symptoms that it had before an engine swap (after the first one blew)