Slow engine response when foot lifted from throttle pedal (decelerating)

Maintenance/Repairs
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1

I drive a '99 Chevy Tracker with the 2Liter engine, a 5 speed manual transmission and 110K mi. on it. When I lift my foot from the throttle pedal in preparing to shift gears the engine takes a very long time to reduce it’s RPM. This is a problem, when up shifting, as the transmission is spinning too fast for smooth gear engagement. Does anyone have any ideas on what could be causing this?

The engine idles normally under all other circumstances. It is only slow to decelerate whenever I lift my foot from the throttle pedal. This makes up shifting very slow and/or causes the gears to sometimes grind slightly.

Thank you,
Leo

2

First try cleaning the throttle body to make sure the throttle plate isn’t gummed up.

If that doesn’t fix it, the Idle Air Control valve is what controls the idle speed between shifts.

https://www.rockauto.com/en/moreinfo.php?pk=942676&cc=1353754&jsn=427

Try removing it and clean it with throttle body cleaner to see if gum and varnish is causing it to react too slowly.

If that doesn’t fix it the IAC valve probably requires replacement.

Tester

3

Good advice and great insite. I’ll try these fixes, which now that I hear them sound right on. Thank you.

4

@ Tester gave some great advise.
The only other thing I can add is that you could have someone step on the throttle and release it while you watch under the hood at the mechanism where the throttle cable is attached. You may see something out of place that is hanging up the cable. You should be able to do this with the engine off.

Yosemite