98 Manual tranny - Unexplained engine revving

[coolbane]

Hello all,I have a 1998 2.2L Camry manual 5 speed. Since I purchased this car 3 years ago, it has always had a very annoying habit whereby the engine revs increase when I depress the clutch to change up to the next highest gear.

For example, if I'm changing from second to third, I generally change up at around 2800 RPM. When I release the accelerator pedal and depress the clutch, the engine revs will often increase by 200-300 RPM for 1 to 3 seconds before it then begins to drop back. This really makes the gear changes very jerky unless I wait a few seconds until the revs drop down before I engage the higher gear.

Several Toyota dealers have told me that this over-revving occurs because of North American pollution control requirements (something about burning residual fuel in the inlet manifold) . I don't believe this because I have had several manual 5 speed cars and I have never seen this type of over revving on any of them.BTW, this over-revving only occurs when the engine is warm.Any suggestions for diagnosis would be greatly appreciated.

[xtremeskier97]

Let off the gas earlier. Ive driven a Gen4 5spd and never had that issue.

[Kitto]

I know what you are talking about, my 95 5sp 4 banger do this too... I think most of the cars do this...including 96 Subaru Legacy, 96 Mazda Miata, 94 Honda Integra... I have owned all these cars over a year, they all do these...

[coolbane]

Thanks for the feedback.

I’ve driven standard for 25 years now and I have never seen this bad over-revving when selecting the next higher gear on any other problem!!! I have driven some cars where the revs hang for a second or two before dropping down, but not this bad.

Also, my wife has a 5-speed Honda Civic, it definitely does not have this kind of engine delay when you change-up thru the gears.

There has got to be something specifically wrong with the fuel injection, emissions controls or CPU to cause this problem.

Any further suggestions would be greatly appreciated.

[Kep]

This is a stretch but maybe it has something to do with the air conditioner. There is an idle up control that activates when the AC compressor is on. Now for a question, On a manual Camry, does activating the transmission clutch have any sensor for shutting off the compressor clutch during the shift? If it did, and if the AC idle up system didn't react quickly enough I could envision an RPM increase. I would be especially suspicious if it only happened when the AC was running but it might impact it even if it wasn't.

Shear speculation.

Kep

[coolbane]

Interesting idea, Kep.

Unfortunately, it does not apply to my problem because I very seldom use the A/C.

However, is it possible that the Idle air control circuit is continueing to allow air into the engine after the accelerator is released becuase of a faulty control unit or a ECU issue?

Alternatively, could a stuck EGR valve cause this type of over-revving?

Thanks,