I was determined to fix my stalling without computer tuning or drilling, and after scouring many threads (too many) I pieced together a solution to idle problems after a cam install. This should probably NOT be used to raise your idle above the target idle speed. What I am posting below is what I have done on my 98 LS1 M6 with a Hotcam, other PCMs may (but probably won't) react differently.

The issue is that your vehicle becomes dependant on your IAC to maintain enough idle speed for your vehicle to run after you install a cam. Why? I have no idea...less vacuum at idle I guess. Since your IAC is working so hard to keep you idling, sometimes your idle will dip based on computer variables that are far too complicated for me to care about when my car won't idle right. Drilling the throttle body takes up some of the slack for the IAC and prevents the idle from dipping so much. Overdrilling causes excessive idle speed. But drilling is a sloppy way to adjust something that can be done with the set screw on the throttle body.

Instead of drilling use the set screw on your throttle body, and here is how:
1) Hookup Autotap or your diagnostic tool of choice. You will want to monitor your IAC, Idle Speed (and desired idle speed if you don't know it), and your Throttle Position.
2) With the key in the ON position, adjust your tb set screw until your Throttle Position is 2-3%. You can do this all at once, or gradually in 1% increments if you like. (I started with +3% and ended up adding another +1%).
3) Turn your key to the OFF position.
4) Unplug your Throttle Position sensor.
5) Turn your key to the ON position for a few seconds, and then OFF again.
6) Plug in the TPS (don't know why nobody caught me forgetting that step) and then turn your key to the ON position and restart Autotap. Your Throttle Position will now be reset to 0 degrees (or really close like 0.4%, the point is it is now reset).
7) Start your engine. Autotap is unable to pull IAC counts from my computer, but you can watch the Idle Air Control Airflow in grams/sec. A stock vehicle should show about 20 grams/sec, and that should probably be your target. I overdid it a little myself with the extra 1% to reduce the amount of control the IAC valve has over my idle. My grams/sec is between 5-10.

I wish I had measured the IAC airflow before the change, but I just wanted to get the thing to idle better. You will probably see much much more than 20 grams/sec if you Autotap it before the adjustment.

Basically the point is that you CAN adjust your throttle body with the set screw withough messing up your Throttle Position reading. WOT will still be between 99-100% (perfectly normal). And you will now have an idle that doesn't go too low. If any of you guys have anything to add to this, please do...or if I have made some error in doing this.

 

LOL,I love the title.Was thinking that last week when I saw this monster hole in the blade.Before Edit I tried that a few times but the car alway's learned it out to crappy idle/start again.
Like alot of people might say and I agree with is that any Cammed car should be tuned which can fix all idle/start problems,nevermind the better throttle response/midrange power you pickup.

 

I have done this on several cars...works great.

 

thanks for the post I am going to try this

 

I am very interested to hear your results if you want to post them afterwards.

 

going to the track wed. don't what to change anything until I get back will let you know thur. or friday

 

I dont even have the idle air hole in the blade and idles perfectly, actually better than it used to with a stock TB.....

 

That is the way I tuned my cam a while ago. Works great.

 

i dont know about yall, but i had to do that and drill the TB to a hugh size plus i started a second hole. now it idles perfect.

 

Step # 4) Unplug your Throttle Position sensor. when do you plug it back in? after # 5?
I would like to do this also. I just installed my ported t/b from jantzer, my stock tb that I sent back for core was drilled . dont really wanna drill my new ported tb so this sounds like a good idea. Ill be using tech 2 for this procedure. thanks in advanced


Mark

 

Step 4 is right (forgot to add that sensor plug-in). I did it again today just messing with mine. You turn the key on for a few seconds so the computer acknowledges a problem with the sensor (or a sensor change), and then when you plug it back in with the engine off, then the computer sees it the next time you turn the ignition key to ON and recalibrates. If you follow the steps above you can't go wrong. It works great!

Hey...how did you get a tech 2?

 

Yeap same with me. Followed a tip from a mechanic I new 4 years back. Works well to help A4's with 112 lsa cams.

 

Thanks man. I work @ Hertz rent a car. We have gm's tech 2 fords ngs and wds, we also have the new one from otc genisys. Ill try this tommorow and let you know what happens.

Mark

 

FYI, a 3/32 allen wrench works great to turn the screw.

 

3/32 was starting to strip, so I switched to a star bit (whatever they are called), because that appears to be what actually fits in there...I haven't pulled it out to check though, but the star bit fit right. Then I turned the bit with a wrench. Crude, but effective.

 

if you take the screw out of the opening. Then screw it in from the top. You can agjust it without removing it.

 

You do have to be careful when using an allen wrench since it is a Torx head screw but flipping the screw works even better.

 

Yep, that is what I did. Its a great tip.

 

It works good on cams with a 109 LCA also... Got mine to idle at 800 rpms with an A4...

 

if we can monitor IAC steps but cannot monitor Idle Air Control Airflow in grams/sec what steps or counts should I be looking for?