97SSdude

I installed kooks LT's on my 97 SS and I removed egr and air. I had PCM4less tune the ecm to remove the egr and air. I put the ecm back in and car started fine and runs fine. Problem is when I'm going down the road and shifting gears (M6) the rmp's dont seem to drop quick and sometimes they increase a few hundred rpm's before they start to drop. But before they drop enough I have already shifted gears and the car jumps because the rpm's are still alittle high. I was wondering if anyone had an idea what this could be? Is it because I removed the egr and air? Thanks!

maybe2fast

sounds like a vacuum leak

Injuneer

I'm assuming these are lifting throttle shifts.

The PCM opens up the IAC valve as RPM increases, to prevent the engine from stalling if the throttle blades close suddenly. I think the way the IAC reacts to this is controlled by something called the "follower tables". Sound like it might be a programming issue.

Mystery Bird

I agree, either vacuum leak of the throttle follower vs. IAC vs. speed table.

97SSdude

Ok thanks guys. I guess I'll give PCM4less a call or email and see what they say.

maybe2fast

Is your air duct on properly?

97SSdude

Yes the duct is on. Everything seems to be where it's supposed to be. This all started when I got the tune. I just thought someone on here had a thought of what it might be before I contacted pcm4less.

97SSdude

So I heard back from pcm4less and they told me to check tps voltage? I don't see how this could be the problem when it was fine before the tune? I have a feeling I shouldn't have let them tune it now.

Injuneer

Since it's so easy to check the TPS sensor, why not give it a try?

Harness unplugged, key on, do you have 5V between the black and gray wire pins in the harness connector?

Harness plugged in, is the closed throttle voltage between 0.30-0.80V across the black and dark blue wires?

Slowly open throttle blades, watching voltage. Voltage should increase slowly, with no dropouts or spikes, until the throttle is wide open. WOT voltage should be about 4V higher than the closed throttle voltage.

ACE1252

Also make sure your throttle is not hanging up in some way(bad throttle spring...etc).