RPM Pause on deceleration

[ab6cr]

Hi all, and thanks in advance for the help. I have a 1999 Rodeo with 3.2L and manual transmission. Runs great and no trouble codes.
Here's the problem, minor but annoying:

When upshifting through the gears, I push in the clutch and let up on the gas pedal. I can watch the RPM gauge drop from ~3,000 rpm (assuming I shift at that rpm) and when it drops to about 2200-1800 rpm it will pause for perhaps 1/2 second before dropping again. This causes me to have a jerky shift sequence.

So what is causing the pause??

Thanks for any help.

[szg3vr]

I have a '98 manual and had some problems with the RPM speed too at about 140k. The problem started affecting the RPMs during idle. I replaced the idle air control valve on the throttle body and haven't had any troubles since. The part cost me about $50 at Autozone, but it was not OEM.

[ab6cr]

Thanks for the response.

Well, I did some more checking of the engine by pulling the electical connector off of various sensors. After pulling off a connector I did the RPM test as in my post above and and there was no change except for when I disconected the TPS (Throttle Position Sensor). Then the RPM dropped fine, but of course a TPS trouble code appeared on my scan tool. With the TPS connector on, the scan tool reads the TPS percent just fine (linearly) as I press the gas pedal. (Did this with engine off). In otherwords the TPS test out fine, but I replaced it anyway along with the IAC too.

I still have the same problem, no change as posted above.

Any suggestions???

THANKS!!!!

[ronhl80]

Just an idea, maybe check inside your throttle body and see if your plate is sticking at a certain position?

[rodeo02]

Could be a dirty TB, sticking throttle cable, bad IMG, etc. If it doesn't stall out, cause perfomance issues for you, or light up the CEL, I wouldn't worry about it.

Joel

[ab6cr]

Originally Posted by rodeo02

Could be a dirty TB, sticking throttle cable, bad IMG, etc. If it doesn't stall out, cause perfomance issues for you, or light up the CEL, I wouldn't worry about it.

Joel

Thanks for the reply,
It is not a sticking cable or dirty TB as when I disconnect the TPS electrical connector the delay goes away.
The delay happens just as the clutch is being reingaged as in shifting up a gear. To have a smooth transistion the RPM needs to be lower or I have to press the gas pedal to further to keep the rpm from falling from clutch engaging resulting in a jerky shift.
Sorry if this doesn't make sense but it is a real nuisance. Yes, I know how to drive a clutch. Been doing it for 30 years....
Likewise, when you let up on the gas to slow down(clutch engaged the whole time) when the rpm drops to ~2,000 rpm the pause causes the car to jerk as the momentum shifts from slowing to constant speed and back to slowing again.

I'll take a look at the IMG.

Thanks again!