drilling throttle body?
Thread Starter
Teching In
Joined: Aug 2005
Posts: 26
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drilling throttle body? I am having problems with my idle. I have a 216/224 113. I never had this problem with my first motor, but after getting my new motor my idle sucks. keep stalling at stops.
MODS added to 2nd motor.
LS6 intake
Aluminum flywheel
I'm a little confused with drilling the tb blade. Does that raise my idle speed? Should I even attempt this on vettes knowing it's different from the F-bodies?
MODS added to 2nd motor.
LS6 intake
Aluminum flywheel
I'm a little confused with drilling the tb blade. Does that raise my idle speed? Should I even attempt this on vettes knowing it's different from the F-bodies?
TECH Enthusiast
Joined: Mar 2003
Posts: 618
Likes: 0
From: San Diego
There is no reason you should ever drill a hole in your throttle body with current technology except in the most rare of circumstances. Have someone tune it. If they aren't sure how to do it, refer them to this reference material 
TECH Senior Member
Joined: Apr 2004
Posts: 6,157
Likes: 1
From: Texas
AIC should open up enought for it to idle correctly
Sounds like you need to have it tuned.
I didnt drill the TB when I had the trex because the tune was good.
Yes drilling a hole in the TB will allow more air to go in and in turn raise your idle.
Sounds like you need to have it tuned.
I didnt drill the TB when I had the trex because the tune was good.
Yes drilling a hole in the TB will allow more air to go in and in turn raise your idle.
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TECH Senior Member
Joined: Apr 2004
Posts: 6,157
Likes: 1
From: Texas
Idle Air Control valve - (IAC sorry it was a typo)
It opens up to allow air into the intake when the tb is closed so your engine wont die at idle.
Im not sure what a cranes cam tuner is but im 99% sure this is a tuning related problem.
I would take it to a shop and have them scan/tune it with hptuners or something similar.
It opens up to allow air into the intake when the tb is closed so your engine wont die at idle.
Im not sure what a cranes cam tuner is but im 99% sure this is a tuning related problem.
I would take it to a shop and have them scan/tune it with hptuners or something similar.
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Do not drill your TB...you never need to do that..it IS a tuning issue..and it can be fixed with proper tuning...I am really surprised that you would have an issue with that mild of a cam...my 233\233 .595\.595 112 would idle on the stock the tune before the custom tune was done.. 
Thread Starter
Teching In
Joined: Aug 2005
Posts: 26
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I don't see any IAC on the throttle body. I pulled the TB off the manifold. All I see is the motor and the TPSensor, no idle controlling valve. Anyways, I figured out what the problem was, it turned out to be the IAT sensor. It reads about 140F. So I bought a 570ohm resistor and plugged that in, it runs fine now. I think the thermistor went bad sometime a few months ago. Thanks alot everyone, especially the person that had that tuning link.
Originally Posted by Mirek
Do a good search and see who recommends drilling and exactly why.
Then drill the hole.
Then drill the hole.
Any body that tells ya to drill a hole does not know what they are talking about..take that to the bank...it is tuning and nothing more...check around with people who know what they are talking about..or check with a competant tuner and you will learn the truth..happy new year..
TECH Fanatic
Joined: Mar 2003
Posts: 1,946
Likes: 1
Originally Posted by Mirek
Do a good search and see who recommends drilling and exactly why.
Then drill the hole.
Then drill the hole.
You need to log your Long Term Idle Trims (LTIT) and your Short Term Idle Trims (STIT) from a cold start to operating temp. This will show how far off you are. Add the LTIT and STIT values together and adjust (add to) your Base Runing Air Flow (RAF) for each specific engine coolant temp range. Make sure you are using the same units of measure i.e. G/sec.
EFI-Live or HPTuner will let you do this... It is one of first and most simple things you can do with them... The process is even automated in HPTuner now... couple clicks maybe two logs and you are done...
I have used this on my last four cams and my F13 (112lsa) which idled perfect at 800rpms....
Last edited by SideStep; Dec 31, 2005 at 08:06 PM.
On The Tree
Joined: Dec 2004
Posts: 100
Likes: 0
From: Satellite Beach, fl
I drilled a hole out of frustration. Was using un named $%$#@ programer. Then I got EFI, closed the hole, tuned one start cycle from cold to operating temp, no more stalling or stutter. Same cam.
Originally Posted by redfulcrum
I don't see any IAC on the throttle body. I pulled the TB off the manifold. All I see is the motor and the TPSensor, no idle controlling valve. Anyways, I figured out what the problem was, it turned out to be the IAT sensor. It reads about 140F. So I bought a 570ohm resistor and plugged that in, it runs fine now. I think the thermistor went bad sometime a few months ago. Thanks alot everyone, especially the person that had that tuning link.
