I just replaced a 21 year old worn out air coupler between the throttle body and the plastic coupler to the cold air intake added by a previous owner. I bought one those smooth intake couplers and ditch the OEM accordian unit. Why the heck not, can't hurt right?
I was surprised but the throttle response was night and day better. Much better acceleration everywhere in the RPM range from throttle tip in to redline. Idled just bit lower and ran smoother at all rpm's.
The intake roar was now louder than my Corsa extreme exhaust. Only thing I can think of is that the original part was collapsing with air flow or it really is much more restrictive. Visibly it certainly looked like it.
So.. after a couple days of combo city and interstate driving it's back to the way it ran before..
The ECM must have dialed back the throttle plate opening in relation to pedal input.
I disconnected the battery last night and bled off any capacitor voltage storage by touching the disconnected battery cables together to dumb the ECM. Reconnected the battery and yep. It's much faster again.
So it looks like I need a tune? Can the pedal to to throttle plate correlation be recalibrated with an HP tuner or the like? One to one would be nice. I am told that it takes 60 percent pedal input or more to get a wide open throttle plate with a stock tune.