Throttle issues after porting any ideas?

[flynaked]

Engine is a bolt on 6.0L with stock intake, TB and MAF, I ported the TB last weekend and now I have some issues. I thought oh great I came across the bore and opened it up, but I don't think that's the issue as I only had 1000grit or 800 max come across it while I was polishing. I checked all the vacuum caps etc, doesn't appear to have any leaks. But here's the deal, it idles fine on start up, it will drive around fine up to half throttle etc, but once I get into the throttle anymore than 1/2 it will stick at around 2k rpm on the way back down and wont return to idle. I did file the throttle stop a bit but I don't think thats the issue, its not even to 90* at WOT. The tune is the original mail order tune that I got the truck running on after the 6.0 conversion. Could porting the TB have made enough of a difference to be a tune issue or is there maybe something else I'm not checking? Thanks for any input id really like to get this figured out, since I can't drive it right now.

[flynaked]

One more thing to add, the original tune was for a 5sp, now it has a 9.5in converter and a th400, drove fine with the stock TB but I'm wondering if it has anything to do with the returning to idle issue since it is now an auto trans?? Just a thought

[farmtruc]

i'm sure you have gone over all ur mods to the throttle body, but there has to be something ur overlooking.
if you only polsihed the bore that would have xero effects on idle.

if something is sticking it's mechanical ,

both of those transmissions wouldnt affect idle, as far have having input for idle; as far as the pcm is concerned it's the same one.
an auto 60e or such would make a diff.

i'm assumimg a few things so post up some more details

the iac could be sticking, does idle come down eventually or do u have to play with the the pedal to unstick the high idle?
also a vac leak will act exactly the same way; high idle until the iac eventually closes.

[flynaked]

Ok I just went out and hammered it a lot and nothing, couldn't get it to do it, 3-4 stop lights too and nothing wierd. As soon as I got home and drop it down and it hits hard in park and hangs at 15-1600, I blip the throttle a little to see if it will come back down and nothing, so it just hung there and I shut it down. Sounding more like a vac leak huh?? Kind of wierd that its actually quite a bit different than earlier today only doing it in park and all. I haven't been able to check the IAC for function as I don't have anyone to hit the keep for me tonight. The TB was the only thing I changed before driving it again, everything else is stock lq9.
Question, is there any kind of spacer on the throttle shaft that mine is missing, I got this TB from a friend and never saw one when taking it apart, seems to maybe have a little side to side play in the shaft, not sure if its too much. Thanks for the input, much appreciated!

*couldn't find any spot in the throttle travel where the blade sticks on a hot or cold engine, so I think thats ruled out*

[93GMC]

Ok I just went out and hammered it a lot and nothing, couldn't get it to do it, 3-4 stop lights too and nothing wierd. As soon as I got home and drop it down and it hits hard in park and hangs at 15-1600, I blip the throttle a little to see if it will come back down and nothing, so it just hung there and I shut it down. Sounding more like a vac leak huh?? Kind of wierd that its actually quite a bit different than earlier today only doing it in park and all. I haven't been able to check the IAC for function as I don't have anyone to hit the keep for me tonight. The TB was the only thing I changed before driving it again, everything else is stock lq9.
Question, is there any kind of spacer on the throttle shaft that mine is missing, I got this TB from a friend and never saw one when taking it apart, seems to maybe have a little side to side play in the shaft, not sure if its too much. Thanks for the input, much appreciated!

*couldn't find any spot in the throttle travel where the blade sticks on a hot or cold engine, so I think thats ruled out*

Re-tighten the TB just to make sure. Mine did this.. .stupid TB spacer