1993 XLE 3.0 Camry Acceleration Problem

I'd first like to say that it is great that there is a board where Camry owners can help each other out.
With that being said, I have a strange problem.
I have a 1993 Camry XLE 3.0 with an acceleration problem. While traveling over 55 mph, it you attempt to go WOT, (wide open throttle) the engine refuses to downshift to a lower gear, and will acctually declerate. If you back off the throttle to half way, the engine will downshift and accelerate as it should. It seems as though the WOT condition is causing the problem.
There is no check engine light, the car runs VERY well, except for this problem. The engine has 180K miles and has been very well maintained, timing belts, plugs, wires, injectors, etc.
Any suggestions, before I take it off to the dealer?
-PurdueDood
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PurdueDood
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When did you last get the throttle body cleaned? Perhaps that could cause some restriction or the linkage that opens the throttle could need adjustment.
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Why would you beat on a car with 180k miles, you are lucky it runs.. Try a trans drain and new filter and drive easier
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Would guess, the first item to check would be the TPS (throttle position sensor). This is a rheostat (variable resistor) attached to the throttle butterfly valve that sends signals to the ECM (electronic control module aka "computer"). Simply put, the TPS signals throttle position. Since your car has an electronically controlled transmission, that could be the source of your problem. The TPS can be easily checked with an ohm meter. I'm not sure if the data is in the Haynes repair manual, but the factory service manual will show the correct data. Actually, you could just check resistance to see that it moves smoothly with no dead spots or spikes as you move the throttle from idle to wide open.
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Agree with what you have said Daniel,..the other odd part is he says the car actually slows down if he plants it above 55mph,..that would seem to indicate the ECM is not aware of the WOT,..apart from the TPS you'd think the manifold pressure sensor would signal the ECM the throttle is fully open (manifold pressure drops). If there is a problem in the TPS and/or MAP area, the injectors may not be signalled to open for longer as required.
Jason
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Thank you everyone for your great advice. I will first check the TPS, and have the throttle body cleaned.
The transmission was recently rebuilt, down to the very last part. Overall the car is very well maintained and drives like a dream. It has just recently had a problem with highway acceleration, which has been a concern of both myself and my wife.
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Update:
I checked the TPS with my VOM and I noticed at closed throttle the reading is about 500ohms, as the throttle opens it climbs to nearly 1.8kohms then about 2/3-3/4 throttle it begins to drop back near 1k ohms. This leads me to beleive that the TPS has failed. Anyone know where to get the specs for this measurement?
-Purduedood
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