Assistance Needed

First and foremost I own a 2002 Dodge Durango, 5.9 Liter V8, 4x4.

I have been running into four persistent P Codes over five months; P0121, P0122, P0123, and P0442. It started way back in October 2014 but I didn't really pay much attention to it. Now its severely annoying and I am afraid that i am causing serious damage to the vehicle. Money problems as well as general use of the vehicle have been the reason why I haven't been able to get it fixed, but I refuse to take it to a shop because my stubborn DNA knows I can fix it myself. Also I had been driving around with a muffler that needed replacing for a while, at first I thought this was the problem, but when it was fixed sometime in November 2014, the problem still persisted.

The problem is that the car will not idle correctly. Either there will be a high surge in idling, or a low inconsistent idle that will eventually lead to the vehicle stalling/shutting off. The problem is so bad that in order to drive the car i'll have to have the foot on the brake and gas at the same time just to keep the engine on. Also while driving, the vehicle may not shift gears when at expressway speeds. I realized this when the vehicle would be at 2500+ rpms at 60-65 mphs, which is my usual expressway speed.

I've gone through multiple steps to get the problem resolved:

1. installation of a basic muffler (Novemberish 2014) - No luck, problem still persists.

2. Replace MAP Sensor (Januaryish 2015) - Engine light went off for 10 minutes, returned with codes P0121 and P0122.

3. Replace TPS (Januaryish 2015) - Engine light went off for 10 minutes, returned with codes P0121 - 123

4. Replace IAC (January 26, 2015) - Engine light went off for 2 days. The issue with the gear shifting was resolved as well. I noticed that the engine would rev to around 1200 - 1500 rpms while initially starting the vehicle. Although I thought that may be normal considering the IAC valve is supposed to "open" the throttle wider in colder temperatures. After my two days in Nirvana the problem restarted with a P0442 and eventually lead back into P0121 - 123.

As of February 17, 2015 I still have the same codes.

My thought process is that if I fix the P0442 then the rest of the codes would resolve themselves. But I don't know much about P0442 codes.

Given this information does anyone have any suggestions?

 

Also, does any one know if this may be a sign of a possible bad alternator?

 

this information taken from here
https://dodgeforum.com/forum/1st-gen...ine-light.html


now when you changed the sensors did you reset the PCM? did you remember to disconnect the battery when you changed the sensors (if you didnt it is possible that you damaged one of the sensors). It could also be a bad wire in the loom, or a bad connection at either sensor, i would get out a continuity tester and start checking for bad contacts between the sensor plugs and the PCM.

the 0442 is likely unrelated to the other 3 unfortunately, and is usually a simple fix by replacing the evap lines that connect to the charcoal canister under the vehicle (approximately under the driver seat). These lines are emissions to preven fuel vapors from being vetned into the environment, nothing more.

 

Thanks for the reply!

Unfortunately I did not make those adjustments when I was installing the sensors. Now it only makes sense to check and see which ones actually have a valid connection.

Thanks for the information as well as the tips on the P0442 code. Will reply with results when I get it done.

 

Just got through checking the voltage with the TPS and MAP. The readings are as follows:

PCM to TPS connector - 5.14 Volts (Ignition in "on" position, throttle closed)
PCM to MAP connector - 5.14 Volts (Ignition in "on" position, throttle closed)
TPS backprobe - 3.61 Volts (Ignition in "on" position, throttle closed)
MAP backprobe - 4.67 Volts (Ignition in "on" position, throttle closed)

These tests were made after I reset the PCM and drove the vehicle for 17 - 20 minutes. These readings are definitely off, but I was hoping that they would be off in a way that it would produce 0.0 Volts which could possibly mean that I just need to replace the sensors the correct way. However it is consistent with a P0123 code seeing that, that voltage is really high. (also P0123 is the only engine code currently showing)

From my understanding PCM - MAP and TPS connectors seem normal (around 5 volts) however TPS backprobe with throttle closed should be .35 to .90 and MAP backprobe with throttle closed should be 1.0 to 1.5. The throttle closed readings are like the throttle is half to full opened.

Also %50 of the time I was checking the voltages I heard whooshing sound akin to a washing machine discharging used water and filling up with fresh water. This sound was accompanied by the whir of a motor. It was different from the fuel pump in that 1. I heard the fuel pump come on and off within seconds and 2. the sound I heard was continuous until I turned the key back to the off position.

 

Do you have continuity to ground. Should be less than 5 ohms. Do those sensors share the same ground? Ask yourself what the circuits have in common when checking the schematics.

 

Should be less than 5? Through the manual that I'm looking at the voltage should measure apprx 5.0. Is .14 volts going to throw off the functionality that much?

 

Not voltage. Resistance to ground on the ground circuit. Reference voltage will be 5 volts on the power side.

 

I say completely remove the throttle body and remove the electronics and use 2 cans of throttle body cleaner and an old tooth brush and clean that thing up. Then reinstall.

Replace the TPS.
MAP, I am not sure sounds kind of high but that might depend on the manifold absolute pressure sensor.

I would first fix intake and TPS then go to the next step.