Firechicken

I want my IAC counts in the 30-40 range or what ever it takes to get a good Idle right?

I noticed that drilling the TB hole or turning the screw on the TB stop both lower my counts.
But by turning the screw my TP senser volts go up.

1.Where do I want the TP senser volts to be at Idle?
2.Why has my Idle not gone up after drilling the hole out 3 sizes up from stock?
3.Do I need to do a Idle relearn every time I drill the hole bigger?

Thanks for you help.

Pro Stock John

iTrader: (34)

Well, is it there yet? TPS will go up if you crack the blade open. Too much and it will set an SES code.

Firechicken

John,
Whats the best way to do this? Do I just want to drill out the hole or mess with the screw or both? Because I can get the IAC counts down enough by doing just one of the two. So what way is the best? I thought is was good to keep the TB sensor volts down in the 40s at idle. Or does it even matter?
And why does my idle stay at 750 even though I've drilled the hole 3 sizes bigger??????
Thanks Jeff

Colonel

1. The lower the better. I've found that a lower TPS voltage makes for a less surgy idle.

2. Because your IAC closes up it's pintel more and more (that's why the counts are lower) to keep your idle at what it is programmed for. I don't know why people think they can raise the idle by turning the screw or by drilling. If you screw it or drill it far enough your IAC pintel position counts will hit zero and cause a code which will disable the IAC (yes, your idle can then be too high since the IAC will no longer have any control but this is NOT a good way of raising your idle.)

3. Couldn't hurt but it'll figure it out on it's own.

Get the hole big enough so that the counts are about 20-35 with the engine FULLY warmed up.

Firechicken

Thanks for the help.
Jeff

Pro Stock John

iTrader: (34)

Haha, my car has idled anywhere from 600 to 1200 since I bought it.

Here is how I look at it.

I would just crack the blade a wee bit if for example you just did a converter and you just need a bit more.

I would drill out the hole for a cam. I would first find the drill size for the stock hole, and then go two sizes bigger. Drill it out. Now drive the car for at least a few days. Go from there. If you overdrill you can epoxy the hole up and start over. PCM will set an SES lite if your idle is more than 200 over 'desired.'

Now, I just have put a towel behind the blade and have drilled the hole while leaving the TB on the motor. Yeah we don't want shavings going into the motor. None go into mine.

Right now I still have to play with mine, it idles poorly on cold start, and I have to feather it.

Colonel

Hmmm...I wonder if the idle control behaves differently on different years.

PSJ, here is what I found on my 2000.

Drill hole larger- IAC counts come down. Idle stays the same.

Drill hole a little more- See above.

Turn screw so that it holds the throttle blade open ever so slightly - Idle goes slightly higher...but then the IAC counts come down as the computer learns. Idle returns to match the "Desired Idle RPM."

Turn screw a little more- See above.

Maybe on some cars you can permanently raise the idle rpm a little above the programmed "Desired Idle RPM" but that wasn't the case on mine. I tried, and tried, and tried. The 'puter readjusted for everthing I did so long as I didn't render the IAC non-functional.

[ December 19, 2001: Message edited by: Colonel ]</p>

CHRISPY

With the screw turning <img src="gr_stretch.gif" border="0">
Can I get the IAC's stable at 35-45 with the car hot and they'll never move or throw a code?
Or do I have to drill?
thanks,
Chris

Colonel

IAC counts are going to move some with engine temperature and weather conditions. That's why you don't take them much lower than 30 or so.

[ December 19, 2001: Message edited by: Colonel ]</p>

The Alchemist

iTrader: (19)

I just recently got Auto tap and I am trying to locate the setting to monitor IAC counts. The only option I have found is the IAC position feature.

Any help would be appreciated.

Tom99SS

iTrader: (2)

I have done both, or should I say the people who installed the cam did the drilling and I did the idle screw. Here is how it has worked.

1) Drilled TB to get IAC counts to good range. Car still wanted to die. Even died while making a turn. Did a few Idle Relearns / reset PCM by disconnecting battery for more than 30 minutes and did the same.

2) Decided to reset IAC. That is disconnected battery, pulled TB off and moved the IAC pintle all the way open. Waited 30 minutes and reinstalled everything. Idle jumped up to 3000rpm at startup (was to be expected) but settled down and the IAC started to learn. Still idle was too low and would surge. Got this idea from ls1.com post.

3) Raised idle via idle set screw and small shim on top of screw to get the idle at 750 rpms (I did take a volt reading first before touch screw so I would know my baseline, .54 volts).

Results, no codes, idle is at 750rpms (+/- 50 rpms) and idle does not surge but has a very slight lope to it. I did get a p0507 code (High idle) once and thus turned the idle set screw down a 1/4 turn and this has not come back (DTC freeze frame had rpm at idle at 757 rpms, over by 7rpms).

If I decide to get costume programming I will lower the idle set screw back to .54 volts first.

This has helped me with my cam and an A4 car.

- Tom

<img src="gr_grin.gif" border="0">

phantom meneSS

As far as TPS voltage goes, on the Aussie cars the TPS resets it self to zero everytime the ignition is turned off and back on, so if its the same on your cars(i cant see why it would be differant) the TPS position is no concern.