About a month ago I bought a 1992 Dakota with approx 135,000 Km ( that's Canadian for 85,000 miles). I had to drive about 300 miles to pick it up and on the way home I noticed that it initially would shift into overdrive and then, after it warmed up, it ran in 3rd gear. Funny.
When I got it home and drove it a bit I found that it had to be warm to run with power and would still pop and backfire through the intake. It ran like a carb that was lean. I started studying the situation and replaced the TPS as many people suggested this might help. It did for about a day and I have heard that many fixes last about a day. I read somewhere that a fellow spent $600 for a tuneup for a days good driving. Sounds expensive.
I read about poor grounds and a lot of other problems and learned a lot of new three letter abbreviations for components and said a number of four letter words and still I could not find a solution.
Early this week I went for a drive and the shifting was still erratic. It seemed at times that the timing was way off and it was trying to push the motor in reverse rotation Bad noises! and I continued to read and consider. It seemed that all problems involved the computer and the various components on the motor and drive train. The subject of the 60-pin connector on the PCM came up repeatedly and I had the thought that there could be some corrosion in that connection.
Yesterday morning I went out and took the connector apart ( after disconnecting the battery) It didnt look too bad in there but i sprayed it with electrical contact cleaner anyway. The stuff I used is Nexxtec tuner control cleaner and lubricant. Basically it is a potentiometer cleaner, available at Radio Shack. I put the connector back together and hooked the battery back up and went for a drive.
The motor ran very well and the tranny shifted very well. No popping or farting through the intake!
The truck was almost impossible to start in the morning and would hardly idle. If it was not warm it would only run for a moment and then stop or it would run at very high revs and then die. This morning I went out and hit the starter and away it went. Running at a smooth and steady idle at about 800-950rmp. WOW. I took it out on the highway for a short drive and it is like a new truck!

At this point I believe that most of the problems that I have read about come from resistance in the 60 pin connector on the PCM. Not a lot of resistance as the connections didnt look too bad. Just enough to give false readings to the computer and throw the whole system off.

What do you think? The truck runs and shifts great so far. I will continue to monitor how it works and, when it warms up here I will probably pack the connections with Di-electric grease and I believe it will keep on going for a long time.

I love my truck even more now that it works right! Try this fix and send me a 6 pack if it works!

Old Toad

 

Cool. I'm glad you got it. That is a great tip.

 

So we took a road trip today and the truck ran pretty well. Smooth and steady on the way there and a bit hesitant at times on the way home. Stopped by at a friends house on the way home and after the motor cooled it was all farty and wanted to quit at low rpm's. Shifting was great at all times.
Could this be the IAC module on the throttle body? I have a new one coming from ebay... Hope it is the fix. Probably going to get the transmission fluid changed this week. I think it is way past due.
How does a bad oxygen sensor effect the system and what are it's actions?
Any assistance is great!
Thanks for the wonderful resource!
Mike

 

I ran the codes and learned that the O2 sensor is not working. Will this be the final fix? No one knows!!
Mike

 

The O2 sensor is a post combustion sensor. The computer does read it to help determine fuel trim, but the computer mainly looks at the MAP sensor, and IAC for those things. Bottom line, the engine should run pretty good whether the 02's are working or not. I would look at fuel pump or some other cause.

 

The PO said that the fuel pump had been serviced.

 

Start by checking for codes, and then hook up a fuel pressure gauge and a spark tester to try and determine what is being cut out. It sounds like fuel.

 

I borrowed my father-in-law's 96 silverado while I replaced the water pump in my Ram about 3 months ago, and the thing ran like an absolute dog. Fairly rough idle, hesitant, stumbling, and crappy gas mileage... I drove it to Autozone to get the new water pump and figured I might as well get the codes read while I'm there. IIRC 3 out of the 4 oxygen sensors were throwing codes, but he has still not changed them or even tried to fix it because he barely ever drives it.

I personally would replace it if it is throwing a code, but just because it is throwing a code doesn't always mean that is what is causing it to run bad it could just be the result of something else. Good luck

 

Thanks Guys. This weekend I will install new cap, rotor, wires and remove and clean the throttle body. We will know where we stand on these issues then. It continues to run better all the time. I believe it has been sitting for some time, probably has some nasty gas lying around.
I had the tranny drained and new fluid installed and it seems to be working better.
We will see how things work after the tuneup!?!
Mike

 

So I borrowed a friends garage and installed new cap, rotor and wires along with removing and cleaning the throttle body and IAC. I made sure to blow lots of cleaner through all vents and loosten the really stuck carbon on the plates and in the bores. I looked into the plenum and there was no pooling of oil there and the inside is quite dirty.

I took the truck for a drive and it is still having some issues with low speed running although it runs well at speed. Driving on the highway the truck would cruise quite well in overdrive for some time and then shift somewhat erratically and sometimes ping. Then it would return to running normally and repeat the process. This did not occur at regular intervals or under any particular condition that I noticed but at random times and situations. I have a new IAC unit coming.
The gas tank is running low so I bought a can of seafoam and put it in and ran long enough to get some into the system. I hope that this will help clean any gunk out of the system and will see how it is in the morning. There have been issues with cold starting so I will see how it reacts to being left out at around zero F and see if it starts in the morning.
Any ideas with the sketchy running after the new wires and cap & rotor? Bad gas maybe?
Thanks
Mike