Throttle body changed...

Bdenmark73 · Dec 1, 2021

Ok so finally got a chance to install the 75mm throttle body and plenum and I like how much smoother the butterfly moves compared to my stock one and gas pedal feels much smoother with the set up as well... but having problems with it at times with shift points and trying to kick down when WOT. I knew the ECU would have to relearn the idle and air flow with curves with the change but is it common to not want to kick down into passing gear at 50 or 60 mph at certain times? Its not doing it all the time, so am thinking it might have to be something it will have to relearn... or am I going to have to do the old drain the ECU power trick and have to let the car start over relearning the new throttle body and shift points? Any help from my fellow SN95 brethren will be appreciated

07GtS197 · Dec 1, 2021

I would start by resetting the ecu. I’ve never heard of that happening but you just never know. Usually when you start getting random shift weirdness it’s the mlps or neutral safety switch but no need to jump to anything just yet.

Bdenmark73 · Dec 1, 2021

I was thinking the same thing because it wasn't happening until the throttle body change

ttocs · Dec 1, 2021

if the IAC is like my holley system there really isn't any learning. You program the IAC hold position that it stays at while your driving as well as the decay rate that it returns to idle when you get off the gas. These are numbers you set that it goes to and then when it goes to idle then it just keeps it at the programmed idle speed vs coolant temp.

07GtS197 · Dec 1, 2021

With a change in airflow the ecu will need to relearn how to control idle. These ecu’s have some ability to learn on the fly but an idle relearn will be quicker.

Bdenmark73 · Dec 1, 2021

Ok so ECU relearn has been completed and it's idling fine, from standing start WOT to 90 mph pulls extremely fast and hard... but at cruising speed say 60 mph, when giving WOT it will not kick down a gear still, but if I lift off and let 5he rpm drop about 200 so it tries to downshift on its own, give it WOT and it kicks down and wants to go like a bat out of hell and didn't do it before the throttle body change... does anybody have any suggestions?