Trans Trouble?

[rokkitpete]

I recently purchased a 98 sho with 98K. I noticed that the rpm seems to jump 100-200 rpm when the car is on the highway. Car seems to shift fine when accelerating. Is this the start of a trans failure:rainshit: or is it simpler than that?

 

[LJRuddy]

Do you have your climate controls on during this?

If so, that is normal. Every time the compressor clutch cycles, the torque converter briefly unlocks and then locks.

 

[rokkitpete]

I have tried it with a/c on and off. Doesn't matter. It seems to do it more when going down a hill with the cruise on than going up a hill. I just had ford flush the trans. but it didn't make any difference. Probably needed to be done anyways.

 

[LJRuddy]

If you are going down a hill with the cruise on, it could simply be the fact that the cruise takes out all throttle input as the hill is steep enough to not require throttle input. Every time you let off the gas and then get back on it, the torque converter will have to re lock

 

[rokkitpete]

Thanks for the replies. Now I need to get the cams welded.

 

[stephen newberg]

Actually, the only position where it will not happen, IIRC, is if the climate system is set to vent. In all other positions the climate control system runs, and as a result the 300 rpm bump will occur. You can get rid of it with a new chip and a tune, if it is bothering you a lot, though I think that is about a $500 operation. Paul could tell you for sure as he does them.

pax, smn

 

[SHOZ123]

Stupid Ford programming. It will happen in any Climate Control position but vent and floor.

I set the tuners so it will unlock still with throttle movement but stay locked for when the AC cycles. Also adjust the time it will take before it locks again.

 

[rokkitpete]

It really doesn't bother me but I would think the locking/unlocking would ******* the transmission. Seems dumb to me but what do I know.

 

[stephen newberg]

It will happen in any Climate Control position but vent and floor.

Right, floor too. I had the feeling I had forgotten one. Thanks Paul!

pax, smn

 

[whiteguy3]

You can get rid of it with a new chip and a tune, if it is bothering you a lot

Can that be done through the tweecer (CalEdit)?