2001 Dodge Ram 1500 5.2l with 4x4 seems to jump/buck into overdrive. The RPMs drop at the same time as the bucking at around 40-45mph so I know it's from 3rd to 4th gear. Overdrive always works. I noticed sometimes it does go into overdrive unnoticed cuz I have been watching the RPMs and it won't buck/jump. The transmission is really good other than this problem. It drives city/freeway no problem and shifts nicely. I'm honestly stumped about this. I appreciate any feedback. Thank you. -Dan

 

You have a miss. Probably blown plenum, old O2 sensors, etc. Everything that goes along with the HUGE vacuum leak on the bottom side of the intake. If pushing the O/D off button makes it run 'smoother' again, that is indeed your problem. (probably getting misfire codes as well?)

Known issue with the 2nd gens.

Welcome to DF!

 

Thank you Hey-You for the response. Funny enough I just had the intake gasket replaced by a good local shop because it was leaking. I also had a whole new distributor assembly put on with new cap, rotor, plugs, and wires. All of this using Dealer Mopar parts. It was not cheap lol but the truck definitely runs better. The truck has always done this overdrive jump/buck and I was hoping the repairs would fix it but it hasn't. The only code the truck had was for an O2 sensor and I had them replaced and now there are no codes. The truck does not have a cat so do you think that has something to do with it? And yes, the truck is perfect with OD turned off.

 

Cat likely doesn't have anything to do with it.... PCM would just whine about it if it were actually a problem.

What brand O2 sensors got installed? Our trucks seem to dislike the Bosch sensors......

Did the shop reset fuel sync when the replaced the distributor?

90% of the time, bucking at around 45mph (the speed at which the truck shifts into O/D, and TCC engages......) is a sure indication of a misfire. Do you have access to a scanner, so you can look at misfire counts? (you have to have quite few before it actually sets a code...)

Think I would be tempted to have a look at plug wire routing, and making sure firing order is correct. The dist is a pain to get to, so, it's pretty easy to make a mistake.

If you are brave..... (stupid? ) Take the truck out to a lonely stretch of PAVED road, and stomp on it hard from a roll. (up to about 30 mph) let the engine get north of 3500 RPM for a few, and see if the CEL starts blinking at you. (misfire) It won't necessarily be in O/D at the time, (likely it won't be) but, if you get misfire under these conditions, it becomes patently obvious. (that blinking light is REALLY hard to ignore.)

Running a can of seafoam thru the intake probably wouldn't hurt you either. Clean out some of the crap that has accumulated from the blown plenum.

Could also try unplugging the front O2 sensor, and see if the truck runs any better. If it does, replace the sensor... NTK, or Denso Please.

How many miles on the truck?

 

You seem like you really know what you are talking about. I like you lol and thanks for the help so far. It has 108k on it right now. I do not know what brand the O2 sensors are so I will definitely try unplugging the front one since the back really isn't needed. I do not own a scanner but plan to get one soon. I looked at the way they wired it and it looks fine to me. Can the plug wires touch? And they did say that they set the timing on the new distributor.

 

Timing isn't adjustable. The only thing you change when you turn the distributor is injector timing. You get a TINY little window of "correct".... plus or minus 7 degrees.... Not something you can set by ear. You MUST have a scanner that can read the data to set it properly. PCM gets all of its cues for ignition timing from the crank sensor. Hopefully, they actually used a genuine mopar unit, as our trucks really don't care for aftermarket sensors in critical locations.

Plug wires can touch..... but, they shouldn't be ran right next to each other. Most of the 'stock replacement' wires will crosstalk like that. (which gives you a miss.....) There is a service bulletin in the FAQ/DIY section here on plug wire routing. May wanna have a look at that too. A "good quality" wire set will alleviate most of those problems.

If you suspect plug wires, get a spray bottle with just water. Wait until it is good and dark, start the engine, let it idle, and start spraying water on your plug wires. If they are leaking, the light show will let you know. (and it looks really cool too....)

At this point, recheck everything the shop did, short of disassembling the intake.

 

Since its the 3-4 shift, I wonder if its a problem with the 3-4 accumulator spring. I rebuilt a 46re back in tech school because it had a weird 3-4 shift. Turned out the very last coil on the accumulator. Spring broke off. It still shifted but wasn't right.

 

I checked the front o2 sensor and it's NTK so that should be good however the back one is not labeled but looks different... hmm. But that one shouldn't matter anyways.

 

Where exactly is that located?

 

I'm definitely going to look into the plug wires and try to separate them... I noticed that two of the wires are laying on the headers... These are "Hi-Temp 7mm suppressors". Should be dealer replacements. Should I try to get heat shields or something for these wires or not even worry about it? My guess is they will melt over time.