I am posting this for the next poor soul who trys to solve this problem.

So here is the scoop on this 1992 Dodge Dakota 5.2L 4x4 LE truck. This truck would stall when coming to a stop, would only start by feathering the throttle while cranking and ran really rough below 2500 rpm.

My son originally bought this truck and was told it had been sitting for quit some time.

The following is a list of parts that were replaced and did not fix the problem.

Engine air temperature sensor.
Throttle position sensor.
Map sensor.
Crank sensor. (definitely ugly looked kind of melted.)
ECM (After it totally died, the second rebuilt one died, currently on the third one.)
IAC solenoid.
Distributor Cap
Rotor Button
Spark plugs.
One fuel injector (cylinder #5)

The distributor was timed using the back probe 5 volt trip method with the crank set on 17.5 degrees.
Searched for vacuum leaks until I was sick of it. Even used an unlit torch for search by gas pickup. No external leaks found. Check the wiring splice under the fuse box in the engine bay as well.

After all this my son was driving to work one day and the truck quit altogether and would not start. He was done. Wanted to trade it in on new car so I bought it from him for what the offered him for it. Turned out to be the fuel pump. So I put a new fuel pump on it and it started right up but it would still stall and run rough.

So I did some research and discovered the air intakes on a 5.2L 318 C.U. engines for many years have a pan and pan gasket on the bottom of the intake or probably more correctly now called an intake plenum. After some reading I discovered the gasket between bottom of the plenum and this plenum cover fail quit often and cause an internal vacuum leak. The tell tell sign is to hold the throttle body open use a flash light to shine light into the bottom of the intake the if you see oil or burned oil residue build up you have a plenum leak. Mine was bad.

I replaced the intake/plenum gaskets. While I had it all apart I also replaced all eight fuel injectors and the EGR valve. This engine now runs 100 times better than before. I hope this help the next poor soul who runs across this problem.

 

Sorry you found out this way. It is a known issue with the Barrel intakes. The problem is caused by the dissimilar metal of the intake and the plenum. There is a permanent fix sold by a couple of companies. It is essentially a plenum plate made of 1/4 inch aluminum and gaskets.

 

Thanks for the reply onemore94dak! This engine is now running just fine however I still have some computer codes coming up even though the check engine light is not on. The codes are 12 (Battery Disconnect), 15 no vehicle speed sensor input (the speedometer does not work) 23 air charge temperature sensor, 24 throttle position sensor, 55 end of codes. I discovered the "COMPLETE" intake gasket kit I bought came with a shiny brand new thermostat so I installed it. Lo and behold the thermostat was a 185 degree instead of the factory recommended 195 degree. So I am wondering if the air charge temperature sensor is picking up a colder engine temp? The nagging TPS sensor code is about to drive me crazy I have replaced that TPS twice. Any idea why it keeps tripping this one?

 

You'll keep getting the 12 until you get I think it is 50 starts after the last time you disconnected the battery. There can be codes with no ck engn light. IDK if there is an Air temp/thermostat connection. I changed all the sensors in mt TB and Intake when I did the plenum kit. I have heard the TPS can be installed improperly but I don't know what the symptoms would be. I think you need to check the speedo cable.

 

I'd check the speedo cable at the transmission end - sounds like it's come loose, or was taken off.

It's (internal) drive gear --> Vehicle Speed Sensor (VSS) --> Speedo cable --> Speedometer. Since both the VSS and speedo are inoperable, I'll bet they were taken loose or off during the intake work, and not put back on.

Edit: Oh, and for 1988, it is 50 start cycles. That's not start/turn off/start/turn off, but start / drive / turn off / wait at least 15 minutes / lather, rinse, repeat.

RwP

 

Ok So the speedo cable is installed and connected on both the VSS (Vehicle Speed Sensor) end and the Instrument cluster end. I replaced the VSS with a shiny brand spanking new one and no joy. Both the speedometer does not work and it still kicks a code (15?) I think? Yes I checked it. So now I am thinking maybe the "speedometer pinion gear" (see page 14-91 of the factory service manual for picture) may be broken missing or otherwise not turning. So how about it? What do you think? Is this possible? Could that be the culprit? I would take a screen shot of the FSM figure 23 and post it but I am fairly sure that violates some rules here or might get me sued by Dodge.

 

The cable can be bad internally. I would suspect that first.

 

Yah, but a bad cable won't kick a 15 code ( presuming it IS a 15, no VSS output signal ).

Yes, that speedometer pinion gear can pop out of the cap. Took four tries to get my "new" 29 tooth gear in (when I bought my truck, it had a 32 tooth gear, and as a result the speedo indicated LOWER than I was going ... )

I hope posting pics / PDFs from the FSM doesn't get you in trouble, I've done it a few times. (Not to mention, check the FAQs and stickies in the subforums ... )

If you take the plug off the transmission, two notes: 1) Have it pointing as uphill as possible, put a drain container under before you pull it, and be prepared to top the transmission off, since you'll be breaking the seal. 2) Pay careful attention - the unit is non-concentric, and you turn it to one of four "clock" points. Note the clock point (i.e., which numbers are pointing which way) and put it back the same way.

RwP

 

I had an egr problem that was just like that. Egr was sticking open sometimes.

 

haha yup. sound all to familiar to my 1992 5.2L 4x4 i had. never got as bad as yours but was the same problem. its like it had a farting issue and just let up on the power when stepping on the old girl. after i got them fixed up it like the truck got a second life. wish i didn't tip her on it passenger side and screwed the body on it.