Another_User

Ooops.
<----pwnt

Actually I just wanted to throw that in, just in case some other sucker with a 98 tried to log desired IAC counts. I already lost that battle. I asked to get it fixed...the fix was removing the option to log it...apparently it never should have been an option for me to log with a 98. So basically HPTuners pwnt me. LOL!

WS6FirebirdTA00

iTrader: (33)

my car does that now too, so log dynamic and desired and then shift the table? what do you do about the ends when you shift the table, if u go left then what do you put on the last one?

P Mack

iTrader: (6)

I'm almost positive you won't have to go to the left, especially after you adjust your tb for the cam.

WS6FirebirdTA00

iTrader: (33)

ok cool

MeentSS02

iTrader: (11)

Yeah, I can't really see any way you'd have to adjust to the left with this table. Basically, from what I can tell, you use this table to tell the computer to be ready for more air than it was originally expecting since you (and not the computer) are letting more air in (by adjusting the set screw/drilling out the TB).

RedHardSupra

iTrader: (1)

could someone write it up in some easy steps sort of instruction? it's 6:22am and while i'm interested, my brain just ain' up to it yet

99whitews6

iTrader: (2)

Just wondering if you know what your TPS voltage is at idle? I have the same IAC counts at idle although I cant set the screw any higher. I am at .78 volts right now and if I go to 0.8 or higher my TPS will not allow me to reset it to 0% TPS; which means that it idles at 2% and 1800 rpms.

I really want to bring my IAC counts down without drilling

P Mack

iTrader: (6)

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.

WS6snake-eater

Hey P mack, have you noticed any difference in your drivability since doing this? Did it help buck or surging, or hunting idle?

MeentSS02

iTrader: (11)

I'll certainly take a stab at it...

As it came from the factory, your car is expecting approximately 12mm^2 of area that your engine can draw air from at idle (with the TB closed, of course). If you alter the throttle body, change to a larger throttle body, have to adjust the idle set screw due to a cam, etc, you are changing the effective area in the TB that your car can draw the air from. This is evident by an idle that will stick at something like 1000-1100 RPMs as it is settling back down to idle. The IAC vs. Effective Area (Edit -> Idle -> Idle Airflow -> IAC Position vs. Effective Area [under the "General" heading]) table is meant to tell your computer how much area it can expect to draw the air from.

1. Get your IAC counts in line by adjusting the TB set screw/drilling out the TB, whichever you choose (I'd recommend the former rather than the latter).

2. Once you get them where you want them, you now need to log the Dynamic Air Flow and the Idle Desired Air Flow. These numbers will most likely be off. If your Idle Desired Air Flow is smaller than your Dynamic Air Flow, you need to adjust the IAC vs. Effective Area table to the right.

3. Notice in the table how the columns 0-12 are zeroed out. This is telling you the computer is expecting to see 12mm^2 of area to pull air from at idle. If you can figure out how much your new area is after you have adjusted the TB, good on ya! I, however, could not. So this will be trial and error.

4. Copy the existing table from where the values are not zero all the way to the right. Now, zero out another 4 or so more cells (until 0-20/whatever all read 0). Now paste back in the original table right after your last zero (this would now be in column 22), and your table will fill back in, clipping off the last four numbers at the end.

5. Log your Desired Air Flow and Idle Desired Air Flow, and see if it is closer. Once again, if your IDAF is smaller than your DAF, then you need to adjust the table to the right some more (that is, 0 out some more columns). I adjusted mine so 0-22 are zeroed out, cell 24 now has a value of 1, cell 26 has a value of 10, etc).

6. Once you have them close, your car should now stop hunting for an idle when coming to a stop.

Feel free to add/ask questions. I'm a rookie at this tuning stuff, so please don't take this as the gospel.

MeentSS02

iTrader: (11)

It certainly helped my hunting idle issues when coming to a stop, and I don't even have a cam (just a ported TB).

WS6FirebirdTA00

iTrader: (33)

i am not understanding you here, by getting your air counts in line what do you mean by this? is there something you log to figure this out?

MeentSS02

iTrader: (11)

Yep, log your IAC position...some people say it should be between 30-50 at idle with the AC off, but mine is even lower. If you read up, you'll see where a guy was getting 95 at idle, which really limits what your IAC can do to control your idle when you turn your AC on (it can only open so far, after all).

So to keep your IAC from having to open as much, you crack the throttle body with the set screw, and make sure your TPS% still reads zero (you probably already know how to do this). This lets more air in manually, but your computer doesn't know this since the TPS % is still reading 0. That's where this table comes in handy...you can now tell it what you did, and it will start working with you instead of against you.

Please let me know if that makes any more sense.

WS6FirebirdTA00

iTrader: (33)

ok so you want the IAC position to be low, and then you go and alter the effective area once you get the reading of IAC opening to be low like you would like, correct?

the lower the better because it give the computer more room to compensate?

WS6FirebirdTA00

iTrader: (33)

i noticed that when i rev the car, sometimes the idle will hang higher and sometimes it will dip and recover, this shoudl straiten that our right, or at least help it, i have a ported TB with epoxied holes and copper tubes inserted, so i woudl imagine this changed drasticly

MeentSS02

iTrader: (11)

This stopped my idle hunting issues with the exact same type of throttle body...

I personally don't know how low you can go on the IAC position, but mine sits down in the teens, and is working quite well. I can't for the life of me figure out why people want them to be 30-50 (the wording usually gives me the impression that anything below 30 is bad). I guess if they were too low, your car would start idling high since the computer couldn't close off enough of the idle air flow.

If you don't have that cam in yet, your IAC position should be just fine. Log your Dynamic Air Flow and Desired Idle Air Flow and see how they compare...it took me about 20 minutes total to get everything in line.

Another_User

I modified my base running airflow table and then used poly smoothing on it. That was the only thing that got rid of my oscillating idle at all temperature ranges. I decided against modifying anything else...

MeentSS02

iTrader: (11)

With that cam, I'm not surprised...I think this table definitely helps the whole equation though. For a stock cammed guy like me, this table did the trick.

MeentSS02

iTrader: (11)

That being said, I still need to log my STIT and LTIT from a cold start to see where my base running airflow sits. Might have to work that back into this whole equation depending on what I find.

WS6FirebirdTA00

iTrader: (33)

what exactly is this, can you elaborate? you can pm me if you dont wanna take up this thread. is that the same as the airflow modes??