Dakota wont run right

[1966 dart wagon]

its a 96 dakota v8 auto, 4wd. It started running rough a couple weeks ago, no cel though, finally a cel popped up reading codes P0138(O2 SENSOR) p0135, p0740, p0141, all for o2 sensors cept 740 which is Tq.

Anyways i put new NGK o2 sensors in and it still doesnt run quite right, and still throws those codes as of tonight. It idles like crap at times, barley runs at times, idles at 500rpms, oil light will flicker and it almost stalls, then will go up on the idle. then at times im driving and i go to hit the gas more and it does almost nothing, barely moves then will pick up, almost making me thing its also a TPS and/or idle air controller.

I put a scan tool on it tonight with freeze frame when it reads cod P0318 it says:

Fuel system 1
-Closed loop

Calculated load
-4.7%

Coolant temp.
-192*F

STFT bank 1
- (Negative) 2.3%

LTFT bank 1
- -4.6%

Intake Manifold pressure
- 8.2 in.hg

RPM: 832
Speed: 32mph

Thoughts???

[JDAWG]

take a look at your cat

[ScottD]

RPM: 832
Speed: 32mph



This does not look right, at 32mph rpms should be more than 832. Was it sitting and idling with the scan tool on it and reading 32mph? I've seen speed sensors go bad and read mph when the vehicle is sitting still.

[1966 dart wagon]

This does not look right, at 32mph rpms should be more than 832. Was it sitting and idling with the scan tool on it and reading 32mph? I've seen speed sensors go bad and read mph when the vehicle is sitting still.

it was on freeze frame, and showed the code and the info on the code, i assume that is when it was detected, ya the speed/rpm doesnt make sence, when i ran the scan it says to just have the ign. on and engine off.

[CobraT93]

Sounds like the intake manifold plenum pan gasket leaking vacuum....sucks crankcase fumes and oil into intake causing erratic behavior, O2 faults, rough running and the like. Pull the air cleaner off, open the throttle body butterflies, or better yet, take the T.B. off and shine a light down inside the intake and look for oil, and/or pieces of lower pan gasket broken/sucked in..... This usually occurs in newer body(97-up) Dakotas, but I have seen it on occasion in the older ones.

[turbovanman²]

What's your vacuum at idle? What are the IAC counts?

[Mopar318]

Any time there is a problem with a 2nd or 3rd gen dakota check the battery and alternator and make its holding charge, and charging. Infact right after you read this go check those things!
Then move onto the Intake gasket to check for signs of leakage. Put the scan tool on it at idle and it should read about 18-20 in hg for vaccum. If its lower then you probally need to change the intake manifold plenum gasket.

Edit...Looking at the amount of estimated load I would say you should the vacuum looks too low. Probably the gasket.

[Mopar318]

Sounds like the intake manifold plenum pan gasket leaking vacuum....sucks crankcase fumes and oil into intake causing erratic behavior, O2 faults, rough running and the like. Pull the air cleaner off, open the throttle body butterflies, or better yet, take the T.B. off and shine a light down inside the intake and look for oil, and/or pieces of lower pan gasket broken/sucked in..... This usually occurs in newer body(97-up) Dakotas, but I have seen it on occasion in the older ones.

Its happens pretty quick at 10psi boost.:)

[Vigo]

The easiest way to check and see if that gasket is broken (because you cant always see it) is to pull the pcv and breather hoses off the valve covers and plug em both with your finger. If you pull em off in 5 seconds and it sucks a big whoosh of air in, its probably that gasket.

[Sgt Craig]

Another thing to check is the power steering pressure switch.What happens is when it starts to leak the fluid wicks up the wiring harness to the ECU causing all sorts of problems.Ive seen quite a few do that.

[Turbo3Iroc]

While you have the TB off it is a good idea to clean the AIS motor and passage. Usually causes a stumbling idle, might be contributing to your issues above. Sounds like the intake gasket.

[1966 dart wagon]

I havnt seen coolant in the oil, or oil in the coolant. I was going to clean the ais but still doesnt help with the o2 codes

[Big_P]

said gasket will only cause a vacuum leak and will not cause coolant in the oil or oil in the coolant.

[1966 dart wagon]

The easiest way to check and see if that gasket is broken (because you cant always see it) is to pull the pcv and breather hoses off the valve covers and plug em both with your finger. If you pull em off in 5 seconds and it sucks a big whoosh of air in, its probably that gasket.

did this today, it actually pushed air out.

Looked down the TB looked kinda oily

INtake gasket? oh im going to check the vac soon too