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stalling/poor idling issues 1997 Dakota 3.9L

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Feb 9, 2011, 8:50 PM

Post #1 of 2 (2454 views)
stalling/poor idling issues 1997 Dakota 3.9L Sign In

I am experiencing increasingly worse stalling out problems with my 1997 Dakota Sport 3.9L 2wd, automatic.

Recently I got my diagnostic scanning capability back and I now have the following codes PO138, PO141, PO783 (the O2 faults seem to come and go)

I think I could also possibly have a vacuum related problem. Can't visually locate a problem but engine sounds "funny" when cold, almost like i can hear it trying to suck for air.

Fault: especially when cold, engine will stall out in Drive. Even after it's warmed up, if traffic slows to a crawl or i stop at a light, the truck will stall out unless i keep the rpm's up. Lately i've had to put the transmission into neutral in order to stop it from stalling out.

What had I done maintenance wise lately:
replaced plugs, wires, ignition coil, temp sensor..........removed and cleaned IAC............cleaned throttle body and used recommended liquid cleaners (fuel injectors were cleaned last year)..........had exhaust work done a few months back --> duel leads of cross over pipe into the engine had to be re-clamped. No other apparent exhaust trouble

I am wondering about three things now:
1. EGR valve related issue? btw, does anyone know for certain if the 97 3.9L engines use an EGR ?
2. transmission problem - do i have a potential torque converter problem ? (code indicates a 3/4 shift malfunction)
3. finally, how would i know if my catalytic converter is plugged or no good ?

I know that's a fair bit of info and questions, but truly appreciate any/all advice.

Veteran / Moderator
nickwarner profile image

Feb 19, 2011, 9:40 AM

Post #2 of 2 (2426 views)
Re: stalling/poor idling issues 1997 Dakota 3.9L Sign In

A suspected vacuum leak should be confirmed or ruled out. It can and will cause poor running. With the motor running spray in one spot at a time with some carb cleaner and see if the idle changes momentarily. If it does you have found a leak. To check the cat for restriction either install a backpressure gauge or plug in a vacuum gauge and see what you get for a reading. If vacuum is strong at idle and drops near zero when you rev it around 3000rpm thats a pretty good indicator of a plugged cat.

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