1992 Camaro Z28 with MXO Automatic 4 speed tranny with Overdrive..

Seems my tranny is shifting at quite a high RPM I think.. Anyone know what RPM the car should first shift if you were at a stand still and just slowly starting to drive?

I have been able to get a video of what *I* am experiencing..

Video #1 - If you listen closely you'll hear what sounds like the tranny is TRYING to get to the point to shift but is slow at doing it. As if the engine is revving too high before it shifts.. http://media.putfile.com/100_9778

Video #2 - MUCH better example..

0.15secs - 0.23secs : Can you hear like the engine is revving really high and the trans sleeping when it should be shifting??

0.29secs -[end] PERECT EXAMPLE! You'll notice just before the end of the video the engine is really revving (needle getting awfully close to the yellow!) for a long time before the tranns shifts and you see rev needle bounce back down.. http://www.camarosource.ca/temp/Production%202.mpg

Does this look and sound NORMAL to you guys??? I've had the car since 1998 and NEVER had this problems.. It's really bad going up hill where it is in gear, then perhaps slip down a gear cause the engine revs and I have to put my foot really into the gas pedal to get it to move!!

Seems to do this more as the engine warms up.

 

Maybe the tranny is slipping. How many miles do you have on the transmission? When was the last time the fluid was changed? Does it do this going into every gear, or just 1st to 2nd?

 

157K or so.

Was serviced in June (1st time since I bought it in 98') and had oil changed and visually inspected. This problem seems to occur more when the engine is warmed up for a while, and started I would say around October.

 

If the tranny is in good shape, maybe the oil cooler is plugged up. If the tranny fluid gets hot enough, and can't go through the cooler, the fluid will heat up drastically, and it will most definetly slip. You don't happen to have a temp gauge for your tranny, do you?

 

Nope, stock instrument panel.

Update: Someone mentioned if my K&N's (which have never been cleaned-reoiled) since 2 years ago when I bought them) might be a factor to this? Can dirty air filter(s) (TPI air induction box) by the cause? Doesn't seem likely to me.. But I am heading out to get the cleaner/oiler kit now since I DO obviously need to clean them.. 2 years.. geez.

 

No, an air filter would not cause a problem with your tranny shifting. I think it may have something to do with you tranny oil cooler. Maybe someone with more knowledge of the 700r4 can give some advise. Have you noticed a loss in fuel economy? I wonder what your torque converter's lockup clutch looks like, and if maybe some of it has blocked up the cooler. How does the tranny shift at WOT after the engine is warmed up? If it shifts firm with no slip then we can probably rule the oil cooler thing out.

 

UPDATE: More news on the transmission problem:

I went to my local (like family) mechanic shop and they spent a few hours helping to diagnose the problem.

1. The last place (Transmission shop for a transmission flush, change filter, and fluid) I took the car in (June of this year) put WAY too much fluid. On the tip stick, it was reading RIGHT up to the "S" bend on the dip stick (appox 1 1/2" higher than the most amount)..

Removed excess trans. fluid to the correct amount. Still the same problem.

2. Mechanic went on test drive with me and trial and error with the gear shifting shows this ONLY OCCURS WHEN IN OVERDRIVE (D).

Reserve, 1st, 2nd, Drive "D" is PERFECT. Put it into OVERDRIVE and it's as if my gas pedal is effecting the REVVING of the car rather than powering to the wheels.

He is thinking it is more along the line of a SPEED SENSOR or some sort that deals with the engine knowing when to change into OVERDRIVE. He suspects that the car is going into OVERDRIVE WAY too soon (almost instantly) before the transmissions actually is.

Your opinion? What sensor would this be?