The REAL truth about Idle and IAC counts....
Thread Starter
Joined: Nov 2001
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From: Schiller Park, ILL Member: #317
The REAL truth about Idle and IAC counts.... While reading through many, many threads on IAC counts, I have realized that people have listed many different numbers as the ideal IAC range. That is rather confusing, IMO. So, I ask, what really is the ideal range? I've seen everything from 15 to 50 listed as perfect. How about we all make a final consensus on what they should be for:
M6 car
A4 car in gear
A4 car in park
What does everyone think? List your experiances, all info is welcome and appreciated.
M6 car
A4 car in gear
A4 car in park
What does everyone think? List your experiances, all info is welcome and appreciated.
TECH Resident
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Re: The REAL truth about Idle and IAC counts.... After installing my Hotcam I needed to crack the throttle blade a hair by adjusting the idle screw (I have an M6 so I decided not to drill since the TP is not a big issue compared to an A4). Anyway, MY IACs were around 80-90 and the car would not idle well in different conditions. Now the IAC count is about 8-12 and it idles great in every condition. Just wanted to give you my settings.... Good luck..
Tommy
Tommy
Thread Starter
Joined: Nov 2001
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From: Schiller Park, ILL Member: #317
Re: The REAL truth about Idle and IAC counts.... These are great replies here guys! Exactly the type of info I had in mind. 
I have personally tried a couple different TB hole & idle rpm combos with my setup. Right now I'm at 23-25 in Park (A4) and 28-30 in gear (A4). This seems to be the best compromise so far. When I was at 45-47 in Park and 50-52 in gear, I had more surging and hot start issues than I do now. I have never touched the idle set screw, only enlarged the TB hole.
Let's see how many more people we can get to share their experiances.
I have personally tried a couple different TB hole & idle rpm combos with my setup. Right now I'm at 23-25 in Park (A4) and 28-30 in gear (A4). This seems to be the best compromise so far. When I was at 45-47 in Park and 50-52 in gear, I had more surging and hot start issues than I do now. I have never touched the idle set screw, only enlarged the TB hole.
Let's see how many more people we can get to share their experiances.
Re: The REAL truth about Idle and IAC counts.... Before LS1Edit tuning I went through the t/b blade hole enlargement (didn't work, helped but didn't work), set screw ( made me go insane moving that up and down and get the iac to change, then found out the computer will just keep compensating to what is set in the PCM so without LS1Edit or somekind of custom tuning your wasting your time. You can get it to run a little better )
Now after getting ls1edit, and changing the idle in gear and in neutral 111c to 850 it runs great and no waiting for the engine to decrease rpms until a complete stop(can be dangerous).
I figured that after $2500 in a CAM, Valvetrain and LTHeaders that another $350 for LS1edit to get it running right was worth it.
No ls1edit is not $350 but if you go in with someone it is
Now after getting ls1edit, and changing the idle in gear and in neutral 111c to 850 it runs great and no waiting for the engine to decrease rpms until a complete stop(can be dangerous).
I figured that after $2500 in a CAM, Valvetrain and LTHeaders that another $350 for LS1edit to get it running right was worth it.
No ls1edit is not $350 but if you go in with someone it is
Thread Starter
Joined: Nov 2001
Posts: 34,646
Likes: 2,573
From: Schiller Park, ILL Member: #317
Re: The REAL truth about Idle and IAC counts....
then found out the computer will just keep compensating to what is set in the PCM so without LS1Edit or somekind of custom tuning your wasting your time.
Re: The REAL truth about Idle and IAC counts.... Great topic. 
My 2000 SS A4 is happiest with IAC counts @ 30. Cam is 220º XE-R lobes 112ºlsa installed +4º and converter is stock. The car has a strong idle at 650 rpm but it DOES take some tweaking with Edit to achieve this. I switched to a SLP 85mm MAF and the IAC counts went to 50 and the car surged slightly. I opened the throttle blade with the set screw and returned the counts to 30. Again, the car has a strong idle with no surging. It's my understanding C5s require a little more tweaking with Edit to get idle and surging under control.
Richard
My 2000 SS A4 is happiest with IAC counts @ 30. Cam is 220º XE-R lobes 112ºlsa installed +4º and converter is stock. The car has a strong idle at 650 rpm but it DOES take some tweaking with Edit to achieve this. I switched to a SLP 85mm MAF and the IAC counts went to 50 and the car surged slightly. I opened the throttle blade with the set screw and returned the counts to 30. Again, the car has a strong idle with no surging. It's my understanding C5s require a little more tweaking with Edit to get idle and surging under control.Richard
Re: The REAL truth about Idle and IAC counts.... From what I have read the IAC in Park in the PCM is what the car is going to try to achieve.
Here is what my IAC in Park table is, this is still the stock settings I did not touch them.
-40C -20C 0C 20C 40C 60C 80C 100C 120C 140C
33.00 28.00 23.00 21.00 19.00 14.00 10.00 9.00 9.00 9.00
So at each temp, the car is going to increase the RPMs, which opens the blade, which increases the IAC.
So theoretically, by increasing the RPM for IN GEAR ( ac on and off) from 800 stock to 850, the IAC will come in line.
Mine sit normally around 35 all the time, I have seen stock sitting at 50, and tuned sitting at 50 but this was done by increasing the RPMs to 1050. But to get mine to 50 the idle had to be 975-1000 and just made smoother. I didn't get the 112 lope to have a smooth idle. So to get teh best of both worlds, I have it low enough to stay lumpy but high enough to not surge or stall.
Here is what my IAC in Park table is, this is still the stock settings I did not touch them.
-40C -20C 0C 20C 40C 60C 80C 100C 120C 140C
33.00 28.00 23.00 21.00 19.00 14.00 10.00 9.00 9.00 9.00
So at each temp, the car is going to increase the RPMs, which opens the blade, which increases the IAC.
So theoretically, by increasing the RPM for IN GEAR ( ac on and off) from 800 stock to 850, the IAC will come in line.
Mine sit normally around 35 all the time, I have seen stock sitting at 50, and tuned sitting at 50 but this was done by increasing the RPMs to 1050. But to get mine to 50 the idle had to be 975-1000 and just made smoother. I didn't get the 112 lope to have a smooth idle. So to get teh best of both worlds, I have it low enough to stay lumpy but high enough to not surge or stall.
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Re: The REAL truth about Idle and IAC counts.... On cold starts my R1 cammed 427 will bounce in idle from 950-1100 rpms (like it's hunting for the right amount of idle) and then after a minute of sitting or just driving it immediately it'll idle as smooth as glass. Any ideas why it hunts at 950-1100 rpms on an initial cold start only?
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Verdad Gallardo Re: The REAL truth about Idle and IAC counts.... I assume you have not ls1edited or raised your idle?
The RPMs your talking about sound like the stock rpms when cold.
Here is the stock table - all I changed were the 800's and the one 825 to 850. No more surging or searching. Some go higher to 1050 to get the IAC up.
Temp degrees F: -40 -19 3 24 46 68 89 111 132 154 176 197 219 240 262 284
In Gear A/C Off 1050 1050 1050 1000 1000 1000 1000 900 800 800 800 800 800 800 800 800
In Gear A/C On 1050 1050 1050 1000 975 950 875 825 800 800 800 800 800 800 800 800
The RPMs your talking about sound like the stock rpms when cold.
Here is the stock table - all I changed were the 800's and the one 825 to 850. No more surging or searching. Some go higher to 1050 to get the IAC up.
Temp degrees F: -40 -19 3 24 46 68 89 111 132 154 176 197 219 240 262 284
In Gear A/C Off 1050 1050 1050 1000 1000 1000 1000 900 800 800 800 800 800 800 800 800
In Gear A/C On 1050 1050 1050 1000 975 950 875 825 800 800 800 800 800 800 800 800
