IAC position vs effective area
10-05-2007, 11:31 PM
#104
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The table does affect idle airflow but ask yourself, why is
stock not right anymore?
In my case I have just found that the epoxied TB with 1/4" hole
is only able to let 11 g/sec max, which makes everything over
IAC 150 "no help". Drilled it out to 3/8" and it's way better for
starting, surging and dying with A/C on (not anymore, woot!).
If you take all of your TPS=0 cells from a long log file and plot
airflow vs IAC like this, it may show you something you can use
to true up your Area vs IAC table, or fix the mechanical side of
it. If you are using a stock GM IAC then there should not be a
big difference in slope. Baseline air is your TB blade hole, slope is
IAC plunger coming off the seat, a limiting sort of line (like you
can see for the 1/4" trace) means a restriction besides the IAC
valve itself. Can't see offhand why you would ever see -excess-
IAC-metered air unless it was a non-stock IAC servo.
stock not right anymore?
In my case I have just found that the epoxied TB with 1/4" hole
is only able to let 11 g/sec max, which makes everything over
IAC 150 "no help". Drilled it out to 3/8" and it's way better for
starting, surging and dying with A/C on (not anymore, woot!).
If you take all of your TPS=0 cells from a long log file and plot
airflow vs IAC like this, it may show you something you can use
to true up your Area vs IAC table, or fix the mechanical side of
it. If you are using a stock GM IAC then there should not be a
big difference in slope. Baseline air is your TB blade hole, slope is
IAC plunger coming off the seat, a limiting sort of line (like you
can see for the 1/4" trace) means a restriction besides the IAC
valve itself. Can't see offhand why you would ever see -excess-
IAC-metered air unless it was a non-stock IAC servo.
10-08-2007, 08:05 PM
#105
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Try this, with the scanner on and the key on, adjust the set screw where you want it so it reads 2 percent. Then get yourself a torx bit and unscrew the tps screws. Crank the tps sensor clockwise while you tighten the screws back up. If there was room for movement, hopefully you'll be back at 0%. If not i guess you could try slotting the holes on the tps a little and try again.
03-14-2008, 09:31 PM
#106
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I need help. I just adjusted my IAC and got the Desired airflow almost exactly the same as the Dynamic Airflow at idle.....BUT when I turn on the A/C, the Desired is higher than the Dynamic Airflow by around .2g/sec. How can I adjust this?
Also, the car is still having a hard time finding idle when I clutch in. Do I need to adjust my base running idle airflow or throttle follower or a little of both? Thanks!
-Chris
Also, the car is still having a hard time finding idle when I clutch in. Do I need to adjust my base running idle airflow or throttle follower or a little of both? Thanks!
-Chris
