Idle Problem?

[Kdunham32]

Ok This is what it does: At idle if you bring it up just a little above idle say around 800-950 rpm's it will flucuate up and down almost like its missing. Thats where its most noticeable. You can also notice it around 1800 rpm.

I've got good fuel pressure, I've pulled injectors and had tested, New Vp twice just to rule it out, cleaned MAP sensor and IAT sensor, replaced the APPS with a williams from timbo, cleaned all my grounds just now. I am running a SMarty on level 3. I have no codes except the 1693 and the other one is a fuel calibration error code and when the rpm's at idle do this weird idle like it misses, every once and a great while it will throw the P0500 speed sensor code and the ABS light will flash once or twice.

The Truck runs great other than that.

Only thing i can think is the APPS might be bad.(I may be having a hard time with the calibration of it and setting the voltage correctly, as when i set it i can't get it to stay at a steady voltage reading.) Or my 2nd thought is the APPS sensor is picking up Voltage output from the alternator from having "leaky rectifiers" in the alternator causing the Apps signal to flucuate up and down.

Just my thought? What you guys think i should try next? Or you think i'm on right track????

[Kdunham32]

Nobody????

[Mopar1973Man]

Hmmm... You might fill out your signature with make, model, year of truck, mods, etc... If there is no codes for APPS sensor or VP44 then leave them be... But check the voltage signal from the APPS and make sure is smooth. You might use a tool like a ScanGauge to measure TPS (APPS) movements. I would check the crank/cam sensors since relationship of the timing/fuel is relies on these sensors. Check the plugs and connectors. Make sure you grounds are good... The master ground for the engine is hidden behind the starter. This has the ECM, and all the sensor tied to it. You should be able to put a POS probe in a ground connector of the sensors and the NEG probe to engine block and show 0.00 Volts if this rises above 0.20 Volts then you got a bad ground. As for the alternator you could pull it off the truck and have it bench tested. Make sure they test for diodes and power noise. Just a wild idea... Valve adjustment?

[Kdunham32]

Forgot to put that in there...When i did the VP i also changed out the cam sensor as well since its right there. My truck details should be in my SIG? They not there?

Truck Details: 2002 Dodge 2500HD, Di-pricol pyro, boost, Fuel pressure, Mach 1.6, Rip's 4" Exhaust, Raptor Lift Pump, New VP at 83k, Liner Sprayed N-fab Steps and Rockers. mostly stock for now.....94k on the clock as of now.

How exactly do i do this step by step....

"Make sure you grounds are good... The master ground for the engine is hidden behind the starter. This has the ECM, and all the sensor tied to it. You should be able to put a POS probe in a ground connector of the sensors and the NEG probe to engine block and show 0.00 Volts if this rises above 0.20 Volts then you got a bad ground."

POS means????

Valve Adjustment directions?

Thanks.

[Mopar1973Man]

Forgot to put that in there...When i did the VP i also changed out the cam sensor as well since its right there. My truck details should be in my SIG? They not there?

Sorry I must not of seen it... :rolleyes2:

Truck Details: 2002 Dodge 2500HD, Di-pricol pyro, boost, Fuel pressure, Mach 1.6, Rip's 4" Exhaust, Raptor Lift Pump, New VP at 83k, Liner Sprayed N-fab Steps and Rockers. mostly stock for now.....94k on the clock as of now.

How exactly do i do this step by step....

"Make sure you grounds are good... The master ground for the engine is hidden behind the starter. This has the ECM, and all the sensor tied to it. You should be able to put a POS probe in a ground connector of the sensors and the NEG probe to engine block and show 0.00 Volts if this rises above 0.20 Volts then you got a bad ground."

Ok first go out and download the FSM book.

http://forum.mopar1973man.com/downloads.php?do=cat&id=2

Then look up the wiring for what every sensor. To test ground ability is simple. You'll need a digital volt meter. Basically take the negative probe of the DVM and place it in the ground socket of any sensor. Then take your positive probe and place on the negative battery terminal. If there is more than 0.20 Volts displayed there is a ground issue!

POS means????

POS = Positive and NEG = Negative

Valve Adjustment directions?

Thanks.

Valve Adjustment is here...

http://mopar.mopar1973man.com/cummins/2ndgen24v/valve-adj/valve-adj.htm

[Kdunham32]

So do i have to do that with every sensor or just one sensor?THANKS

[Mopar1973Man]

One or two wires should give you a clue... If both that you choose have volatage above 0.2 then you know you got to chase a ground issue... No you don't need the key on either... Simple story. Buddy calls me up that his father-in-laws jeep won't start. They tried jump starting. They clean battery terminals. But everything they did it still refuse to start or show life in the vehicle. But if you check the battery voltage there was 12.7 Volts. So I started with basic +12V testing finding that power is present. But now NEG probe on the engine block and POS probe on the negative battery post. I showed 12.7 Volts!!!! :eek: I told my buddy to grab his jumper cables. He's all yelling at me that "You can't jump start it". So I used the black side clamp one on the battery NEG and the other black on the block. He's looking at me funny now... I told him go start it... Sure enough it fired right up... The Negative cable failed but the test proved it without tearing the vehicle apart chasing. :biggrin: Strang part of the failure you could take that short 18 inch cavble and hold a ohm meter to it and wiggle it and it would go back and forth 0 Ohm to infinite ohms. Here is the Dodge test... http://mopar.mopar1973man.com/cummins/general/voltage-drop/voltage-drop.htm

[guesswho512]

my 99 was doing something similar...it would slightly bouce at idle...i hit 160k and decided to do the valve lash and after that no more bouncebefore you could see the bounce on the tach and even hear it outside the trucki had 3 valves that were wider than spec and i think 6 valves right on the edge of oki ajusted all of them to the fsm spec...no reason to b in there next year