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Discussion Starter #1
Anyone else have the engine wind up pretty high in first and that slam into second with a pretty severe jolt and boom? had it happen 2 or 3 times now. :confused:
 

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Under what circumstances did this happen?

For example, if you had your foot planted to the floor on the loud pedal, I would expect nothing less.

If you were going uphill, my current car has logic in the transmission controls that detects the slope that the car is driving on. If it detects that it is going uphill, it will delay upshifts to make sure that after the upshift eventually does happen, the engine will have enough torque to maintain acceleration. The downside is that it sounds just like you describe - it revs way up in the lower gear before allowing the upshift. But it avoids a situation where the transmission upshifts early but then bogs down in the next gear causing the car to slow down until it eventually commands another downshift ... "hunting".

Old torque converter automatics traditionally haven't had logic like that - they just let the engine bog down in the higher gear against the torque converter until it starts multiplying torque - but it's more efficient (and generates less heat in the transmission) to lock the torque converter early and use the gears rather than the torque converter - but this means the controls need to anticipate bogging down, and stay in the lower gear to avoid it.

Does that sound like the circumstances in which yours did this?
 

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Discussion Starter #5
Brian, thanks for the post.

I believe the few times it has happened, it has been from a stop light. My van has a lot of weight in it always. I never floor it, no need ... it is a big heavy truck, lets just get it moving. But the description you give is pretty close. Revs way up and then when it does shift, it is with a bang. I am trying to recall if it revs up and I let off the gas and then it shifts ... not sure. Has only done it a couple of times, but now that it has I am more cognizant of it and will pay more attention when it does happen. I do want to say it as been on reasonably level ground when it has happened.
 

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wow. i really dont know what that could be. but that def sounds like something bad. if you can replicate it - i'd bring it back to the dealer to have it looked at.
 

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I've got a story to make you feel better.

I've had a Ford truck start slamming on shifts. It started transitioning from a smooth shifting truck at about 10,000 miles. It got so bad I was sure the tranny was toast. The dealer test drove it and said it shifted normal. Desperate, I replaced the tranny fluid. It returned to smooth shifting and never shifted hard again.

I felt like maybe after the transmission was broken in, the fuild was full of debris. So changing it fixed it.

4 years later my next Ford did the same. I changed the fuild. It fixed that truck too.

So now, I change fuild on any truck I own that does this during the first 25,000 miles.
 

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I would second what Dwight said " change the tranny fluid". Maybe the dealer you bought it from would do it as a courtesy. The tranny used in the PM has been around and has a good reputation overall.
 

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^ It's not a bad idea to change the tranny fluid at some point early in the vehicle's life, to get out any crap that might have shown up from the initial running-in period.
 

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Discussion Starter #10
Good advice, I just changed the oil about 1000 miles ago, I will watch this and plan for a full trans change at the next oil change (10k) unless it starts to do it more, then I will try it sooner.

Thank you all for the help and ideas.
 

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You might consider resetting the computer. That's a "disconnect the battery for an extended time" thing, and the computer re-learns your driving and shifting.

It seems that every once in a while data corruption occurs in the system that determines when and how to shift.
 

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Mine had a hard shift yesterday just after I put it in tow/haul mode to climb the mountains here in Colorado. I was at a stop sign behind a few people and as I moved forward with traffic I thought someone had rear ended me. It had just shifted to 2nd... My old Chrysler minivan used to do the same thing and we always thought the trans would go out anytime but it never has. It has over 350,000 miles on it now and has not broke yet.
 

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I had what I think is the same tranny in my VW Routan. Periodically it would do the same thing. Probably 25 times in 129,000 miles. Felt like it was breaking, but never did.
 

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Crash, what were the results of the fluid change? My first 10k it happened to me 3-4 times and when I changed oil at 10k I had dealer look at it but they couldn't duplicate or figure it out. Since then (3k mi.) it has done it over a dozen times. More often taking a left turn at stop light on flat streets. Anyone else know the fix?
 

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Our Dodge Caravan had this problem usually when we changed drivers. Go from a lead foot driver to a smooth driver or vice versa and the transmission seemed to get confused for a while. It usually settled down quickly. Over 60k on that van with no trouble.
 
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