Here is a scan log of my last run. If you go to the end of the log, the TPS is at zero and the car is in park. My IAC count is arount 120. What should it be at and how do I adjust this?
Here is a scan log of my last run. If you go to the end of the log, the TPS is at zero and the car is in park. My IAC count is arount 120. What should it be at and how do I adjust this?
2000 Trans Am WS6, 383 RWHP 344 RWTQ
2006 GTO, LS2, Cyclone Gray, M6, 1 of 475
2009 Chevy Silverado
It should be at 60-70 with a cammed car.
1) You will want to monitor your IAC, Idle Speed, throttle position voltage and your throttle position %.
2) With the key in the ON position, adjust your tb set screw until your throttle position is 2%.
3) Turn your key to the OFF position.
4) Unplug your Throttle Position Sensor (TPS).
5) Turn your key to the ON position for a few
seconds, and then OFF again.
6) Plug in the TPS and then turn your key to the ON position and restart logging. Your throttle position will now be reset to 0 degrees and about .45-.55 volts. Any higher can put you into the wrong fueling cell.
7) Start your engine, if you are not at your desired IAC position redo the above procedures in smaller increments.
8) If your TPS voltage should be between .45 and .55 volts you may need to drill the mounting holes a little bigger and remove the
locator tab so you can make an adjustment.
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Michigan Snowmobiler
1969 Firebird: 11.67@114 [email protected] 1/8 1.70 60 ft. EPS cam 234/246 .602.606 114+3, 6.0 LQ4, L92 heads milled 10.5:1, Ported L76 intake, ported 90mm Holley TB, 100mm MAF, FIC Custom injectors, Hooker LT, PYPES dual exhaust with an X pipe, 4L65e with all of the good parts inside, FTI 4000 RPM Stall, 12 bolt with 3.73 gears. HP Tuner tuned by me
You say to monitor your IAC, Idle Speed, throttle position voltage and your throttle position %. Do you mean Idle RPM for the Idle Speed?
I don't think there's anything wrong with IAC at 120. It's less
than half of full scale.
The thing that will bring IAC down (aside from more bypass
air) is more spark and proper fueling. Fueling is going to be
bugged by O2 sensor fidelity (cold from headers) and
airflow (VE) fidelity, tending to overfuel after a cam swap.
But there's nothing wrong with 120 IAC counts in itself.
Originally Posted by jimmyblue
If 120 is good then I will leave it.
2000 Trans Am WS6, 383 RWHP 344 RWTQ
2006 GTO, LS2, Cyclone Gray, M6, 1 of 475
2009 Chevy Silverado
IAC counts are adjusted by moving the set screw in the throttle body or enlarging the hole in the throttle body blade. Allowing more airflow into the engine by enlarging the hole or opening the blade with the set screw will reduce IAC counts. The trick to using the set screw is having to reset your TPS after you make the changes. This will ensure you're registering 0% throttle at idle. If you go too far, it will register more than 0% at idle - even after you reset the TPS (described above in post #2 - steps 4 and 5).
2013 Mustang GT
If your P&P TB involved epoxy filling, make sure the
IAC port is opened up to 3/8" or so. I went with a
3/16" hole originally ('Net advice) and it was choking
IAC flow and making surge. Opened it up, and a lot
better.
Mine is not surging. If you say 120 IAC count is good then I am leaving it alone.
2000 Trans Am WS6, 383 RWHP 344 RWTQ
2006 GTO, LS2, Cyclone Gray, M6, 1 of 475
2009 Chevy Silverado
I would open your throttle body by increasing your set screw a touch. That'll bring your IAC counts down. Personally, I would prefer to be at 70~80 steps for a warm idle.
2013 Mustang GT
How do I get my scanner to read the throttle position voltage? and how do I adjust your tb set screw until your throttle position is 2%?
Last edited by ws6ick; 10-05-2009 at 06:27 AM.
2000 Trans Am WS6, 383 RWHP 344 RWTQ
2006 GTO, LS2, Cyclone Gray, M6, 1 of 475
2009 Chevy Silverado
Why do you want to adjust it to 2%. If it reads 2% it is going to hurt the idle.
You add TPS voltage to the scanner just like any other PID.
Sulski Performance Tuning
2000 WS6 M6 - LS6 (long block, refreshed top end), 10.8:1 CR, 90 mm ported FAST, Exo-Skel, 227/232 cam, QTP HVMC, EWP, GMMG, 9" w/4.11s
2018 Sierra SLT 5.3L A8 - Airaid intake tube, GM Borla catback, L86 Intake/Ported TB
I was going by this.
1) You will want to monitor your IAC, Idle Speed, throttle position voltage and your throttle position %.
2) With the key in the ON position, adjust your tb set screw until your throttle position is 2%.
3) Turn your key to the OFF position.
4) Unplug your Throttle Position Sensor (TPS).
5) Turn your key to the ON position for a few
seconds, and then OFF again.
6) Plug in the TPS and then turn your key to the ON position and restart logging. Your throttle position will now be reset to 0 degrees and about .45-.55 volts. Any higher can put you into the wrong fueling cell.
7) Start your engine, if you are not at your desired IAC position redo the above procedures in smaller increments.
8) If your TPS voltage should be between .45 and .55 volts you may need to drill the mounting holes a little bigger and remove the
locator tab so you can make an adjustment.
2000 Trans Am WS6, 383 RWHP 344 RWTQ
2006 GTO, LS2, Cyclone Gray, M6, 1 of 475
2009 Chevy Silverado
I disagree with that, my opinion is that the only thing
you want out of the set-screw is to keep the blade
from binding under vacuum. You want to keep TPS
voltage in the good idle range and not make it go
relearning, because that might well steal from your
WOT TPS %. If the throttle body is not physically
munged then barely-off-seat for the blade should just
give you the right volts.
TPS voltage is not zeroed with a reset, it will keep a higher voltage.
Sulski Performance Tuning
2000 WS6 M6 - LS6 (long block, refreshed top end), 10.8:1 CR, 90 mm ported FAST, Exo-Skel, 227/232 cam, QTP HVMC, EWP, GMMG, 9" w/4.11s
2018 Sierra SLT 5.3L A8 - Airaid intake tube, GM Borla catback, L86 Intake/Ported TB
If you have much of a cam, and you don't adjust for 45-75-ish counts at hot idle (and in some conditions less), you won't have enough airflow at cold-start and cold idle conditions. This problem already exists with tons of 'popular grinds' even with the TB opened up, but if you leave it in the 100s count area at hot idle you will be running out of IAC for cold starts/idle even sooner.
That offset proves to be important. I am working on a car right now that has a Cam Motion custom 232/235 on a 112. SCR is high 11s:1. I have it at about 20 counts at 212degF. There is not enough blade offset and IAC to satisfy the car under about 65degF at cold start. I am requesting a low idle RPM when cold to help stretch the IAC out as well. By high 50-degrees, it will take a little pedal to get it going. We need more IAC sometimes.
My IAC at warm idle is around bounces from 35-40. My Cam is 228/228 588/588 112 lsa. Is this good or not? I thought it should be 40-60.
Last edited by ws6ick; 10-06-2009 at 06:25 PM.
2000 Trans Am WS6, 383 RWHP 344 RWTQ
2006 GTO, LS2, Cyclone Gray, M6, 1 of 475
2009 Chevy Silverado
What is warm idle? like 150s? If so, that is definitely too low. You will end up at 0 and lose control of idle.
180 in Park. How do I bring it up and what should it be at in park? Do I need to adjust the throttle body blade to be opened more?
Last edited by ws6ick; 10-06-2009 at 06:41 PM.
2000 Trans Am WS6, 383 RWHP 344 RWTQ
2006 GTO, LS2, Cyclone Gray, M6, 1 of 475
2009 Chevy Silverado
You bring it up by closing the TB blade a bit... look for 40-45 at 210degF. You will have to use the scanner to force the fans OFF (they have an airflow adder) or set the fans high in the editor (and update PCM) so that they don't run.
So turn off my cooling fans by using the scanner, The IAC counts should be 40-45 @ 210 Degrees in park even with the cam I have. If its lower, close the throttle body blade a little by adjusting the screw on the TB?
2000 Trans Am WS6, 383 RWHP 344 RWTQ
2006 GTO, LS2, Cyclone Gray, M6, 1 of 475
2009 Chevy Silverado
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