I'm struggling to find a good way to describe what's happening with my van, but I'll give it a shot.

When the engine is working hard (accelerating or going uphill), it will sometimes hesitate like it's going to downshift but then changes its mind and goes right back to the gear it was in. For example, let's say I'm driving up a long, gradual incline. I'm in 4th gear, maintaining a constant 65 mph, but after a while the van acts like it's going to shift -- the engine sound changes and rpms drop momentarily -- but then it changes its mind and goes back into 4th gear.

The behavior becomes more pronounced when using cruise control, because it will do this over and over again. The fix is to just tap the brake and back off the throttle for a second, but it's irritating and I'm worried that it might be an early sign of a larger problem. A couple months ago my wife took the van on a long road trip and it did this so many times in a row that the Check Engine light came on. Unfortunately, I don't know what code it threw, because it self-cleared before she got home.

Other than what I've described, I don't really have any complaints about the way the van shifts. The only other shifting issues are that it sometimes makes a bit of a clunking sound when shifting when I'm really gunning it, and there's a small transmission fluid leak at the shift solenoid pack (I top it up periodically, so the fluid never actually gets low despite the leak).

Does this sound like something I should be concerned about, or is this normal behavior for these vans? My dad owned an '87 and a '95 and says the shifting issue is normal, but he had to do multiple transaxle replacements, which I would like to avoid. I want to replace the solenoid pack gasket to fix the leak, but if I'm going to have to replace the solenoid pack I'd rather do it at the same time.

Any insight or advice would be much appreciated.

 

I'd be a little suspect of a leak at the solenoid pack. keep in mind that the solenoid pack is what controls all your gear shifting.

What you describe almost sounds like the TC locking up and unlocking, which is normal behavior. I have heard in some cases of a TPS causing erratic TC lock/unlock, erratic shifting, etc. You may want to test it and see if there are any worn points

 

Thanks for the input, issakar.

Driving home through the mountains two days ago, this "shift stutter" was worse than usual, and the check engine light came on again. This time I was able to read the code: P1391 - CMP or CKP Signal Intermittent Condition. Possible causes listed are:
- Timing belt or chain stretched or jumped
- Faulty Camshaft Position (CMP) Sensor
- Camshaft Position (CMP) Sensor harness is open or shorted
- Camshaft Position (CMP) Sensor circuit poor electrical connection.

None of these seem to fit, though. I'd expect the van to run very poorly (if at all) if the timing chain had jumped, and none of these possibilities explain why I only get this code when I have this shifting issue repeatedly.

The strange thing is, the MIL self-clears whenever this happens (it's off again today, and I never cleared it).

Could this code be thrown due to a bad shift solenoid? Or due to a bad TPS, as issakar suggested might be at the root of the problem? It seems odd that the MIL only comes on when this shift stutter happens over and over, but I don't know if the shifting issue itself is causing the MIL to light up, or if a separate issue is causing the MIL to light up and is also causing the shifting issue.

Any ideas?

 

This may not be relavent to your problem but the 1391 code is a manufacturers code specific to Dakotas and Durangoes it indicates a signal loss telling the computer where it is in the 4 stroke cycle. My pick up coil (located in the distributor (on my truck)) failed and the engine stopped it restarted after it cooled down and ran for short distances ( I wasn't planning on going too far until the problem was resolved) but would not restart until it cooled down again. It's possible under extended load the signal is momentarily lost then reaquired early sign of sensor failure. There were two other codes P320, P340, and a fourth code which has been occurring for about two years P304 which is a misfire in cylinder 4. It has only been a week since i replaced the pickup coil so I don't know if the P304 code will reoccur or not but if it doesn't that would indicate my coil has been the cause of the recurring P304 code for the last TWO YEARS if that's possible for it to go so long before complete failure. The part was not cheap $60 but considering fuel economy is affected it could be worth looking at. Hope this is of some help.