2007chevy5.3l

iTrader: (21)

Ok so i had some free time today and decided to do a mild port and polish on my throttle body. I took out all the rough casting edges and knife edged the butterfly. Not much material was removed in the actual throttle body bore .... I installed it back on the engine and fired it up, I quickly noticed that it idled higher and when the engine was reved it took almost 30sec to return back to the near stock idle. Also while driving the truck i noticed it wouldnt go under 1,000rpm. Will a tune take care of this peoblem or am i screwed??
Thanks for the help guys

nonnieselman

iTrader: (10)

We encountered this problem on my buddys TA with a PP TB..
We messed with it for hours. We even put it on my truck and my truck did the same thing..
I reflashed the current tune on each of ours and they are fine now..

have no clue what happened but the TPS wouldnt read under 14% no matter what we did, until i reflashed them..

2007chevy5.3l

iTrader: (21)

So my ecu is going to have to reflashed/tuned then? It still is the stock pcm

GMCtrk

iTrader: (27)

I'd guess you ported too far into where the blade is.

I had mine professionally done and it idled perfectly when I first started it up.

2007chevy5.3l

iTrader: (21)

I hohpe not, i barely took out any material. Maybe the nbs pcm's are different than older trucks causing it to idle weird

l_kusler

You took the blade out of the body to knife edge it right? Would it be that the plate is binding in the bore when its nearly closed?

If you removed any material at all in the bore where the butterfly is positioned at rest you will affect airflow and idle, its like having an unwanted vacuum leak at idle. The amount of porting and polishing a person can do on these is pretty minimal. Hope you didn't cost yourself a tb.. I would definately check out the operation and try a tune adjustment if that doesn't cure it.

I personally as well have ported my own with no problems in the idle department.

GMCtrk

iTrader: (27)

Well, it probably doesn't take much to do it. When you port these things it's my understanding you really don't touch the area anywhere around the blade.

2007chevy5.3l

iTrader: (21)

Yes i took the blade out, knife edged it with out making the diameter smaller, just the edges were filed down. When i installed the butterfly i did make sure it wasnt binding or sticking and it was all good.

I can see by opening up the bore size even slightly will somewhat increase airflow, thus resulting in a higher idle.

But what gets me is when i first start the truck it idles fine, but when the throttle is moved to a higher rpm is seems to "hang" and come down slowly after a few seconds. When im at a light with it in drive the idle is fine, when its in park it sometimes goes up to 2k to 3k rpm. Almost like the pcm is hunting to find the idle......

budhayes3

iTrader: (19)

14% sounds about right for TPS voltage at idle, I've never seen a TPS at 0%


Is it possible that there's some debris stuck in the IAC or it's passage?

2007chevy5.3l

iTrader: (21)

Alright! I found and fixed the problem. It was the damn butterfly that was binding, I guess it didnt center it on there well enough when i installed it the first time around. It took a second pair of eyes to notice the bind. Thank God it wasnt anything more serious.
After it was all fixed we took it for a spin and it ran like a champ, my butt dyno picked up a few HP also lol.
Thanks again Guys, i do appricate all the help