?'s on Drill Mod on PP TB
12-23-2013, 09:47 PM
#22
The drilling is usually just to make for the IAC bleed the stock TB already has, and the brass tube used to keep that circuit isolated from the plenum so it can be distributed more accurately to each cylinder.
http://para.noid.org/~lj/PCM%20Tutor...litBLMinfo.htm
http://www.hashmarks.com/techtips/throttle_body_mod.htm
There used to be a better site but it went down a couple years ago.
http://para.noid.org/~lj/PCM%20Tutor...litBLMinfo.htm
http://www.hashmarks.com/techtips/throttle_body_mod.htm
There used to be a better site but it went down a couple years ago.
12-24-2013, 10:05 AM
#25
The tube done right just isolates the IAC circuit the way it was from the factory rather than leaving it open to the plenum. The front feed manifold will burn lean in front and rich in back if the IAC circuit is completely disabled as in say the case of a monoblade. The aftermarket TBs that have leaks to the plenum wont show it as drastically but idle and cruise can be improved by isolating the IAC distribution of aftermarket TBs. Done it on a couple cars myself.
How can that possibly be considered a "dumb assed hack"?
How can that possibly be considered a "dumb assed hack"?
12-24-2013, 02:19 PM
#28
I would hate for somebody to type something out instead of all this lame-assed short hand.
Professional Products is a sorry Chinese knock off of an American product. Buying that crap is stealing from the company that made the original.
But, Holley and other aftermarket throttle bodies have that area on the back milled out. I agree, it is wrong.
The 58mm units about never need drilled anyway. Just crack the blades open a little. That open area does need addressed.
Professional Products is a sorry Chinese knock off of an American product. Buying that crap is stealing from the company that made the original.
But, Holley and other aftermarket throttle bodies have that area on the back milled out. I agree, it is wrong.
The 58mm units about never need drilled anyway. Just crack the blades open a little. That open area does need addressed.
12-28-2013, 12:35 PM
#31
Also give the PCM time to learn, I have seen some so called tuners or wannabe's do an adjustment to fix idle issues, start the car, not get the desired idle, then immediately shut the motor off and do another adjustment and just keep chasing their tails..
12-28-2013, 01:15 PM
#32
when you put on a aftermarket TB and have idle issues...then scan and read IAC counts and find they are pegged at 160...your PCM can't command any more movement from the IAC valve as the IAC is out of travel at that point. That is when the "drill" mod or "crack the TB blade" some and then slot the holes on the TPS so those dcv read right can be done. Golen engines has 411 on the how to by cracking TB blade/slot TPS holes on their FAQ LT1 page. My $02 is drill mod.
you do need some form of scan tool though to read wtf your IAC counts are as blindly drilling a hole is not advised. also just a 1/64" increase in the "hole" size makes a big diffrence in IAC counts so take baby steps if drilling. start with a 1/8" hole (same as a stock TB). 11/64" is about as big as I have ever needed on a 383 H/C car to get them at 32....but every motor will be diffrent. Just don't go to big
even if you manage to get the car to idle right and IAC counts are still high, when you turn the wheel or turn on AC putting more load on motor the PCM commands more from the IAC to compensate so idle remains constant. If it is already close to being peged the car will want to stall. IAC counts of 30-35 at idle with motor at operating temp with no AC on is what you want.
you do need some form of scan tool though to read wtf your IAC counts are as blindly drilling a hole is not advised. also just a 1/64" increase in the "hole" size makes a big diffrence in IAC counts so take baby steps if drilling. start with a 1/8" hole (same as a stock TB). 11/64" is about as big as I have ever needed on a 383 H/C car to get them at 32....but every motor will be diffrent. Just don't go to big
even if you manage to get the car to idle right and IAC counts are still high, when you turn the wheel or turn on AC putting more load on motor the PCM commands more from the IAC to compensate so idle remains constant. If it is already close to being peged the car will want to stall. IAC counts of 30-35 at idle with motor at operating temp with no AC on is what you want.
12-28-2013, 01:19 PM
#33
I send a sheet out with all my chips & PCMs for doing this if it the tuning is for a different camshaft. When people say "But I don't have a scan tool." I wonder what the hell they are doing trying to modify an EFI vehicle. That is like trying to work on a carburetor with no screw driver. smh
12-28-2013, 01:38 PM
#34
Even my ~$500 AS&M billet 58mm needed the drill mod to idle properly once I had a H/C. With bolt-ons it was fine though...
I just drilled a stock size hole and adjusted the blades to 30-35 IAC counts at idle and everything was fine. I also isolated the passage into the IAC hole like the stocker does with JB weld and two strips of aluminum bar so it dumps the air into the IAC circuit and not into the main plenum.
I just drilled a stock size hole and adjusted the blades to 30-35 IAC counts at idle and everything was fine. I also isolated the passage into the IAC hole like the stocker does with JB weld and two strips of aluminum bar so it dumps the air into the IAC circuit and not into the main plenum.
12-28-2013, 02:37 PM
#36
Even my ~$500 AS&M billet 58mm needed the drill mod to idle properly once I had a H/C. With bolt-ons it was fine though...
I just drilled a stock size hole and adjusted the blades to 30-35 IAC counts at idle and everything was fine. I also isolated the passage into the IAC hole like the stocker does with JB weld and two strips of aluminum bar so it dumps the air into the IAC circuit and not into the main plenum.
I just drilled a stock size hole and adjusted the blades to 30-35 IAC counts at idle and everything was fine. I also isolated the passage into the IAC hole like the stocker does with JB weld and two strips of aluminum bar so it dumps the air into the IAC circuit and not into the main plenum.
12-28-2013, 03:15 PM
#37
