Rough Idle at Park/Idle in drive

Odd, It roughly idles in Drive at a stop, driving down the road is okay. Lack of power, Lack of fuel Eco. I get 220Miles on a 24Gallon tank? Ew.
Used to get 320?


Well, This is what I have replaced, gone over, checked and my symptoms.
Plugs, wires, Cap, rotor, all pullys, new intake gasket with plenum, new injectors, new intake filter, cleaned TB, New TB Sensors, new Intake Sensors, New Smog related Parts, New Water Pump, New Chain, New Timing gears, Compression is great, fuel rail receives Proper PSI. vacuum would be constant issues? New O2, New Cat, New Flowmaster exhaust system.
Anything around the motor you can think of, PCV, Only Pully I have not changed is the Alternator?


Symptoms - Rough Idle at dead stop in Drive, Or Park. Intermitint issue, Not 24/7.
Rough running feel.
Squeely belt when reved, Alternator Pully??
interfearence in sterio, When driving down the road, I can hear the subs beating even with sound OFF and Sub Selected OFF on deck. Still receives the hitts/ I could stomp on floor and it plays the stomp? I regrounded the Amp, Checked the Battery Grounds, those are good.
Bad Eco, Like I said above.

I have seen a lot of people posting on here about a similar issue. Never find out what it was exactly, Any idea's?

Could alternator possibly be going out causing strain on the pully and as well low voltage or improper voltage for the vehicle.
180k miles on truck


I did receive a Engine light for Injector malfunction.
Get this though, I had key turned over at gas pump for music and filling up. It started pinging that issue? Bad fuel pump? or regulator?

P.S. Truck was NOT started when filling up ofc. lol.
Just on ACC.

FWIW, when my battery was going bad years ago, my idles were a tad lumpy and jumpy. Put a new Interstate in and its been fine ever since, so you might be onto something with questioning the integrity of the alternator.

Well, My Battery isn't even 2 years old. AGM Sealed SLI78AGM From Batterys Plus.
Used to work there, but can always use second opinions on mechanics.

I know the battery is good.

Alternator throws...


13.53-13.57 with Loads, Which I placed AC on, Highbeams and turned sterio to 10 which isnt anything.
No Loads is 13.80 Volts around that.

Normally should be 14.2v no load, then no less then 13.80 with loads in my experience in the store of batterys plus.

As well, getting noise inside the subs, I checked grounds, there all good. Every bump in the road seems to make them hit lol.
Bad Fuel, Malfunction in the injectors? As well if its not supplying good voltage for fuel pump or injectors or PCM it would cause issues.
Its as if its a Vacuum leak, but that would be constant, all the time not once in a while.
Used to be 1 time a month, turned to be a couple times a week now?
Fuel SUCKS. Haha

So I think i'll check alternator and replace it.

It Squeels when reved high, so my guess is that its worn from the 180k miles put onto it.

Well, Replaced the alternator, no change, still roughly idles. I am gonna take in to get the PCM Checked.

Comp test on the motor would be where I start.

Merc225hp said:

Comp test on the motor would be where I start.

Click to expand...

Yeah, Sadly the Regulator is regulated by the PCM. :fp:

Trevorlw said:

Yeah, Sadly the Regulator is regulated by the PCM. :fp:

Click to expand...

Yup. Could have told you that. Usually when the PCM/regulator goes out it causes a huge voltage spike.

dodge dude94 said:

Yup. Could have told you that. Usually when the PCM/regulator goes out it causes a huge voltage spike.

Click to expand...

Well I dont see a voltage spike even when it idles roughly. Just around the same voltage.

I'll have to take in and let someone figureout what it is, Short in wire? Bad Ground? Fuel Regulator or pump going out? Bad Voltage regulator in the PCM? or bad wiring harness and/or cam sensor wearing out.

I'll keep yall posted once I get this done.

Have you replaced the TPS? A worn one will get a "flat spot" causing erratic, inconsistent idle, power loss, and poor fuel economy.
The squealing could also be the belt, they get glazed from heat which can cause a loss of friction. Come to think of it, a sloppy belt will cause irregularities in alternator output. Food for thought.

I know this is simple and you may have already done it, but check and if you want replace your ground straps. A bad ground can cause electrical problems, specifically with a PCM, which can cause problems like the ones you're having. I had a guy tell me one time his truck was acting weird.. lack of power, rough idle. He suspected it was a PCM going bad but and all it ended up being was a bad ground. It's worth a quick look.

Well sad to say the PCM Voltage Regulator is bad. Instant Fails on testing equipment. Everything else passed with flying colors. So Yeah, my PCM is doomed. :/

TPS has already been replaced, its good. As grounds are good, checked them. No Corrosion, tight, snug, good ground. ;')

So yeah, I am stuck with getting a new PCM. Ew.

Dealership - 912$+Program+Core
Orielly auto - 319.99 + Program 75$ and shipping ofc most likely.

So you tell me who I am buying it from

Give these guys a call.

1992-2003 Dodge Truck 3.9L/5.2L/5.9L/8.0L Tuning

Merc225hp said:

Give these guys a call.

1992-2003 Dodge Truck 3.9L/5.2L/5.9L/8.0L Tuning

Click to expand...

I'll give them a call once available, but I did send them an Email and hope they get back to me.

As well, gotta be careful since I live in California Smog Retardation State. Lol
So, I am gonna probably hit the Dealer New or Reman from Oriellys like I said.
Not too sure just yet, A good chunk from Factory, but if these guys are able to program a tune specific for me? That would be wonderful!

This truck I tow a boat, at max, so I want ECO mostly, but if there able to program the PCM to performance to where I just Burn them off? That'd be wonderful! Lol - Power is the Demand now days.

Cali truck ok.

I come up with Mopar part number R6040140AJ

So after searching this part number I get a bunch of Mopar sites saying NLA and some up to $1000+ then I found the one's below, if they have it. I don't see a core charge but you never know.

Edit: Found the core charge.

I can't speak for either site never bought from them so no help there.

http://www.partswebsite.com/moparonlineparts/oemparts/R6040140AJ.html

R6040140AJ Dodge MODULE-POWERTRAIN CONTROL