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1994 3.9L V6 Dakota- I’m thinking the PCM is not right and I am wondering if PCM upgrades on these trucks are worth it or should I just go for a replacement OEM PCM? Here’s the story.
I posted complaining about the low RM’s and poor performance after a lot of work. I did the Hughes Engines Intake Plenum and the timing chain with TSB tensioner. I added all new sensors to the intake and TB. All the tune up stuff & coil, oil sensor, EGR, and had the tranny adjusted.
It has improved responsiveness over time but its not yet right. I increased mileage from 170 miles on the 22 gal tank when I bought it to 365 miles last full tank which I ran dry because the fuel gauge don’t work yet. (its got a new pump)
I took it on a 200 mile trip last week and that seems to have helped it some but the RPM’s are still way low and responsiveness is not yet reliable. I always have to wonder if its gonna decide to delay when I hit it and that makes for frustrating driving as I have to stay behind idiots I would sooner pass.
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Update- I have spoken to the guys @ Hughes Engines who helped me with the Intake Plenum they referred me to a transmission shop in Indiana. Very nice helped me a lot on the phone. He seems to think there are indications of engine running problems which I should eliminate. He also says even if its only the TC he would recommend a customer in his shop do a rebuild just so the new parts don’t break any old parts.
I tried a test he suggested which was to unplug the OD solenoid and drive it to see if the RPM’s go up. I didn’t floor it to see if rpm’s would go up to 4500-5K but the truck drove better and revved better. I figured that meant the motor was OK but he said the hesitation I mentioned was not a TC or transmission issue. When I mentioned the PCM as a possibility he was not sure.
I’m going to price a used PCM and see about finding e local mechanic that will check to make sure the motor is running right/diagnose any issues.
Just made an appointment to have the motor checked be back later today to let you know.I didn’t say anything but “please check if the engine is running right”. That way I avoid creating a problem of them looking for my inexperienced impressions.
The mechanic says on paper he is unsure if its enginemiss ir transmission. They told me the engine was fine. He recommended a rebuilds as he felt it was slipping. There were two codes (I hadn’t checked in a while) 37 & 45. Apparently what I have been describing as jumping is slipping. They recommended a guy named Guy!
I went to see him. He said the codes for TC are basically a way of saying its slipping. He drove it. He felt it wasn’t slipping as much as it seemed to be losing pressure. He figured the pump or internal seals or both either way the fix is a rebuild. $1922.70 or less.
I finally got the numbers off the side of my transmission as it seems if this is a late 94 it will be a 95 transmission and the problem may be a circuit board where the items for both codes would meet on a 95 transmission.
I’m gonna research it and then have to figure out how to get 3 days without a rig. Maybe I will tear into that Ram while I’m home bound.
EDIT The truck in this thread is a Dakota the Ram50 I am referring to after this has a blown head gasket. I should have posted what follows in that thread instead of here but I was tired and being lazy. Sorry for any confusion. I intend to rebuild the tranny as soon as I work out how I am going to go 3 days without this rig.The mechanics told me the head would cost $700-$900 for a rebuilt one and 2 grand total to install it!!!!!
I kept my mouth shut I can get one for less than $400 ready to install. I figure if the block looks good and the existing head is trashed or needs rebuilt I will get the new one and just let them have the old one for core. Oh yea they would not install a head if I got it myself. I suppose that’s normal.The hole sounds like it’s getting deeper. As to the pricing, you have to consider the service you’re getting. We don’t work for free and our expertise comes at a price. I don’t recommend ‘price shopping’ for repairs like that. You often end up getting what you pay for. Honestly those prices didn’t sound unreasonable for a transmission rebuild.
At this point it sounds like you’re ready to start throwing parts at it. This may not be the best corse of action to get the results you’re hoping for and may end up being more expensive in the long run. To me it sounds like you need a transmission replacement or rebuild for starters. It sounds like 2 shops have told you such. I would not ignore their advice and start replacing expensive engine parts that you really haven’t proved are bad. That said, it is your vehicle and you can do with it as you like.
Good luck and keep us posted.
Sorry for the confusion. I do intend to get the tranny rebuilt now that it was diagnosed properly. $1922.70 or less is a good deal. Since I have it I’ll have him put in the new TV cable and return spring.
The guys who checked the motor before sending me to the transmission shop told me that other guy who wanted to do the Torque converter sounded fishy to them too, The guy in Indiana that Hughes gave me the number for said the same thing.
Dirt in the pan does not equal new tc which is how it was presented to me at the time. I allow that experience may have lead them to the recommendation but by not saying so or making a better case related to my symptoms to me it I cannot give the credit for it. I’ve also been told an old tranny will often break down in a few thousand miles if you put a new TC in it without rebuilding it.I forgot to mention the main reason for this thread, The tranny man said the low RPM’s are probably an OEM thing that it is supposed to be doing (lower RPM’s better MPG’s) and he also felt the tach may not be reading true. It seemed to him the real RPMs were about 100 more than was showing at idle.
The head I was talking about is on another vehicle which I posted about on here an 85 ram 50.
I do intend to fix the tranny but I have to figure out how to go without a truck for 3 days or fix the Ram so I have something to drive. I just added that at the end of the post because I was tired and being lazy. I should have put it in the correct thread.Just to be clear. Torque converters don’t go bad in the way that people think they do. In fact, whenever I hear about a transmission problem people often say it’s a torque converter problem. The truth is it’s the torque converter clutch that can go bad, not so much the torque converter itself. Here’s a video I did on the topic.
The reason you replace or rebuild a transmission when you replace a torque converter is because of the work involved. As I said, there’s not much in the torque converter that can go bad, most times it’s a transmission issue. Therefore it’s a good idea to service the entire unit rather than cherry pick parts.
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