Getting ready to put on a new throttle body and was wondering...
Can someone please explain the exact procedure to set the correct voltage on the IAC?
Can someone please explain the exact procedure to set the correct voltage on the IAC?
Question about IAC...
- Thread starter finally
- Start date
Anyone? I know all you guys with new throttle bodies know how to do this.
Hey, thanks Doug!
IAC ADJUSTMENT
You need to set the MECHANICAL idle to about 750 RPMs, by installing the new TB, TPS and only the ELECTRICAL connection to the IAC. TAPE over the holes on the new TB. Start the engine and SET the TB MECHANICAL idle screw for about 750 RPMs ilde. STOP the engine. Remove the tape and install the IAC. START the engine again, the idle shoud be about 750 RPMs. The TPS voltage should be about .98 v. There is very little adjustment aviable to the TPS.
AMB
You need to set the MECHANICAL idle to about 750 RPMs, by installing the new TB, TPS and only the ELECTRICAL connection to the IAC. TAPE over the holes on the new TB. Start the engine and SET the TB MECHANICAL idle screw for about 750 RPMs ilde. STOP the engine. Remove the tape and install the IAC. START the engine again, the idle shoud be about 750 RPMs. The TPS voltage should be about .98 v. There is very little adjustment aviable to the TPS.
AMB
Re: IAC ADJUSTMENT
how do I do this part
I can handle the taping (I hope) but is the IAC attached to the electrical connector during this procedure? Is it placed over the taped holes? Laid along side the TB connected? Disconnected? In my pocket? The guys at billetflow tried for an hour last night but it still idles at 1500rpm if I drive it. They did not try this tape trick.
If I just start it and let it idle it stays at 750, any touch on the go pedal and it won't go below 1K. In traffic it won't go below 1500.
I will try the tape trick if you could clarify (dumby-proof) where/what the IAC is doing during this procedure.
I need help, my TB is a gorgeous, customized work of art and I want it to work properly.
Thanks
how do I do this part
I can handle the taping (I hope) but is the IAC attached to the electrical connector during this procedure? Is it placed over the taped holes? Laid along side the TB connected? Disconnected? In my pocket? The guys at billetflow tried for an hour last night but it still idles at 1500rpm if I drive it. They did not try this tape trick.
If I just start it and let it idle it stays at 750, any touch on the go pedal and it won't go below 1K. In traffic it won't go below 1500.
I will try the tape trick if you could clarify (dumby-proof) where/what the IAC is doing during this procedure.
I need help, my TB is a gorgeous, customized work of art and I want it to work properly.
Thanks
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I just finished my install and just put everything back on the new one in exactly the same position as it was on the stock one and it idle's perfect at 750, in the driveway and in traffic. Didn't do the tape trick. WOW what a difference in throttle responce. With the new TB and the adjusted (firewall adjuster)clutch, it's like a different car.
postban
The IAC is not installed on the new TB untill AFTER you set the MECHANICAL idle on the new TB. Billetflow has had problems with there TBs iddling. If the TB is sticking around the closed idle position, it will not come back to 750 RPMs idle. CHECK the TPS voltage, it may be TOO HIGH.
AMB
The IAC is not installed on the new TB untill AFTER you set the MECHANICAL idle on the new TB. Billetflow has had problems with there TBs iddling. If the TB is sticking around the closed idle position, it will not come back to 750 RPMs idle. CHECK the TPS voltage, it may be TOO HIGH.
AMB
finally
What TB are you using ?? Accufab. Bulletflow, BBKor PHPs !!
AMB
What TB are you using ?? Accufab. Bulletflow, BBKor PHPs !!
AMB
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Re: finally
Using a Billetflow.
I tried the tape trick, covered both holes on the plenum, car would not run at all. It would turn over, sputter at about 400rpm and die. Took the tape off the plenum holes, with the IAC off the plenum. It made a whistling noise, sputtered and died, would not start at all.
I put the IAC back on. Measured idle IAC voltage .97-.99, rpm approx 700 rpm. Took it for a drive, really enjoying the custom Predator tune:burnout:
When coming up to a light it wants to stick at 1500. About half the time it will idle down a little bit, maybe 1250rpm. Rarely it will idle down to 1000. If I tap the throttle up to 2500 it seems to run down to 1000 more often then not. Used to have to do shit like that to tame the Holley 750 on my '69 Firebird 400.
Damn nice night for cruising tonight, shame to be having niggling issues like this.
Using a Billetflow.
I tried the tape trick, covered both holes on the plenum, car would not run at all. It would turn over, sputter at about 400rpm and die. Took the tape off the plenum holes, with the IAC off the plenum. It made a whistling noise, sputtered and died, would not start at all.
I put the IAC back on. Measured idle IAC voltage .97-.99, rpm approx 700 rpm. Took it for a drive, really enjoying the custom Predator tune:burnout:
When coming up to a light it wants to stick at 1500. About half the time it will idle down a little bit, maybe 1250rpm. Rarely it will idle down to 1000. If I tap the throttle up to 2500 it seems to run down to 1000 more often then not. Used to have to do shit like that to tame the Holley 750 on my '69 Firebird 400.
Damn nice night for cruising tonight, shame to be having niggling issues like this.
postban
You NEED to" ADJUST" the IDLE for 750 RPMs with the NEW TBs idle adjustment screw, with the IAC off, and the TBs holes taped up. If it stalles/ does not keep running "ADJUST" the TBs idle screw in about 2/3 turns, it will idle above 750 RPMs , ADJUST it for 750 RPMs. Untape the holes and install the IAC. It should ilde at 750 RPMs. The electrical plug should be hooked up to the IAC for all adjustments.
AMB
You NEED to" ADJUST" the IDLE for 750 RPMs with the NEW TBs idle adjustment screw, with the IAC off, and the TBs holes taped up. If it stalles/ does not keep running "ADJUST" the TBs idle screw in about 2/3 turns, it will idle above 750 RPMs , ADJUST it for 750 RPMs. Untape the holes and install the IAC. It should ilde at 750 RPMs. The electrical plug should be hooked up to the IAC for all adjustments.
AMB
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You really need to give Doug at BF a call. There are issues with the way that the engine vacuum affects the backside of the throttle blade which causes the idle to hang. I also had a high idle for several weeks after installing the TB, but I kept trying different adjustment procedures until I finally arrived at a steady 750 idle. I haven't talked to Doug lately, so maybe he has an updated procedure for TPS/IAC adjustments.
ps. I installed an auxillary throttle return spring to help the TB come back to normal idle.
ps. I installed an auxillary throttle return spring to help the TB come back to normal idle.
I didn't do the IAC thing with my TB.
I installed the TB and set my TPS to about .97VDC as that was the highest I could get it. I found my idle hung high and I had to blip the throttle to get it to come down so I added a extra return spring which took care of it. Then I noticed my throttle stuck slightly so I gave the screw a half turn and my TPS voltage ended up at .989. Still slightly sticking so I gave it another half turn and no more sticking, .99V and 750rpm idle. I did disconnect the battery after each change and the car did take approx 5 drive cycles for the idle to become a steady 750rpm. Works perfect now.
Just don't go bananas with the adjuster screw. If you turn it do it a 1/2 turn at a time and only if the throttle is sticking. The function of the IAC is to make it idle. If the throttle plate is too far open it can't do it's job.
I installed the TB and set my TPS to about .97VDC as that was the highest I could get it. I found my idle hung high and I had to blip the throttle to get it to come down so I added a extra return spring which took care of it. Then I noticed my throttle stuck slightly so I gave the screw a half turn and my TPS voltage ended up at .989. Still slightly sticking so I gave it another half turn and no more sticking, .99V and 750rpm idle. I did disconnect the battery after each change and the car did take approx 5 drive cycles for the idle to become a steady 750rpm. Works perfect now.
Just don't go bananas with the adjuster screw. If you turn it do it a 1/2 turn at a time and only if the throttle is sticking. The function of the IAC is to make it idle. If the throttle plate is too far open it can't do it's job.
Re: postban
OK, the adjustment thing worked. Removed IAC, Taped the holes, started it, sputtering at 300rpms, adjusted screw up to 750rpm, removed tape, replaced IAC.
Now it idles down in traffic just like it is supposed to.
Thanks for a great tip!:thumbsup:
OK, the adjustment thing worked. Removed IAC, Taped the holes, started it, sputtering at 300rpms, adjusted screw up to 750rpm, removed tape, replaced IAC.
Now it idles down in traffic just like it is supposed to.
Thanks for a great tip!:thumbsup:
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