Weird uprev issue, quick burst from 3000rpm to 4000rpm

Diablo3

Yesterday I was driving over a mountain (for those that live in Huntsville, it's the one that divides Hampton Cove from Jones Valley).



Long stretches, long straight aways....at some points along the drive, as you're driving 65, 60....etc, the road dips down, so you have to naturally break to slow down to not hit the car in front of you...or to keep a safe distance.


However, about 3 times this happened yesterday.
When I was around the 65 mark, holding the break in to slowly slowdown, not a slam break...the car went from 3000 rpm's to 4000 rpm's for a split second, then it went back down to 3000 rpm's....Figured it would of been masked a little better,it was pretty noticable.


What could cause this?
Only happened during situations like the one described above, 3 times throughout thedrive on the mountain, both ways.......


Touring automatic '12 Z

MattP725

Not sure but a couple things...

First I would post this in the tuning section... second I would give some more info on the uprev you had done... did you have it dyno tunned, etune or canned tune?

If it was done by a shop I would take it back to that shop and have them re-dyno/tune the car.

If it was an e-tune or canned tune I would contact uprev directly.

Diablo3

Sorry, about using wrong verbage "uprev".
RPM/Acceleration issue would be better used, instead of up rev'd..

It's a stock car, with no modifications done.



It was a quick and noticable 3k-4krpm spike, when slowing down while driving on a mountain downslope.....

flashburn

It just sounds like it downshifted, and then upshifted right after that. Unless you had it in Manual mode, I don't think it did anything wrong.

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MattP725

Almost sounds like Syncro Rev match... it is possible that you have a leak in your idle air control valve. But there are several things I am sure that could cause a rising idle. It "could" be a downshift but I've never owned an automatic that downshifted while braking (it usually waits for you to reapply the throttle so it knows what gear to pick). My Z isn't an auto though so I am talking out my rear on that one.

Your best bet is to try and document it via video phone and bring it to the dealership. If you go there unequipped they will almost certainly tell you they couldn't replicate the problem.

DjSquall

The auto won't downshift until its right about to stall... So that's probably not the issue.

Could be the torque converter locking/releasing.