How to read IAC Counts
 

Hey Guys,

I just installed a CC503 cam and I am having troubles getting my car to run right. I think I need to do the TB Drill Mod, but I dont know how to read the IAC counts. I have been considering getting some live scan software but need some suggestions. What is the cheapest/easiest software to get live scan data? I dont think I need to edit the data as I have no intentions of being a tuner, I just want to have better capability to troubleshoot my LT1 and provide data.

Is there any way to do an IAC count rather than having live scan data? If not, what do you guys recommend for a cheap guy on a budget?

Eehack is free data logging software. Iirc you can check voltage at iac to determine position but I'm not 100% on that.

the tb drill MOD is for people with aftermarket throttle bodies that were designed for tpi cars, do you have one?

I still have the stock throttle body, not an aftermarket one, but I got a mail order tune from PCM4LESS after installing my cam and 1.6 RR and he suggested I either bend the TB stop or do the TB drill mod. After looking at searches, it sounds like the TB drill mod is the way to go, but I dont know how to measure IAC counts.

is your car having idling problems WITH the PCM4Less tune and stock TB?

[QUOTE=derekstl;19586437]I still have the stock throttle body,
he suggested I either bend the TB stop or do the TB drill mod.

WHAT?? Bend? Drill? Never!

Yes. He said that since I have a bigger cam in it that it needs more air at idle. The way to do that would be to either adjust the TB stop or to do the drill mod and enlarge the hole thats already in my TB.

[QUOTE=moehorsepower;19586645]Well what should I do then?? :huh:

Derek

your car a 97 OBD2 car, right?

IIRC freescan or scan9495 is for obd1

if the car won't idle because the IAC is maxed out at 160 than you either need to drill the stock hole larger or crack the throttle blades open and then slot the TPS holes so you can rotate the TPS back to get VDC in range

....But you need a scan tool that reads IAC counts. My Actron scan tool does not read IAC

I had to drill my stock, bored to 52mm, when I went to a slightly larger cam with my 383 than I had on my stock bottom end H/C motor. I have autotap and a old laptop (Vista) that will run that software to read IAC counts. The program crashes a lot but will read, among other things, IAC on OBD 2 cars. I drilled the hole 1/64" bigger

I would not blindly drill the hole larger unless you have the ability to read IAC counts....to confirm if in fact they are high....and the idle issue is not tune related

Yes sir it is, 97 and OBD2.

I dont know for sure if my IAC is maxed out or not because i dont have a scanner that can read it, but I suspect that is whats happening.

This is what I was planning to do but need suggestions on what software or scanner to buy. I looked up autotap but they dont sell their product anymore. Right now the only thing I really know of is HP Tuners with the VCM Scanner Standard interface for $349.

No doubt you are correct, I dont want to mess with it at all till I can scan it and know for sure, then be able to dial it in correctly. I didnt spend all this money in upgraded parts and headaches and labor over the last several months to just start drilling holes and call it good enough!!

LS or LT1 motor?

It is an LT1 motor.

IDK why the OBD2 scanners don't read IAC. The read just about everything else.

I have not used HP Tuners but suspect it would read IAC. Check out their product info.

The symptom of a max out IAC is motor won't idle, especially when power steering or AC kicks in

I wound up drilling mine to 11/64" for my 383 H/C. Stock hole is 1/8" (8/64). Every motor combo will be different. The IAC was at 120 at idle but quickly pegged at 160 when any other load was on motor. Each 1/64" larger size dropped quite a bit.

You want 30-35 (32) at idle

A shop with a Tech 2 should be able to read IAC count if they would scan for free or cheap. But you would need to drill the 1/64 larger and check again (unless car idles good) before drilling larger

alternate method is crack open the TB blades with the stop screw on TB. Then you need to remove the TPS black top part and slot the holes so you can rotate it back compensating for the amount you opened TB more. You measure how much by using a DVM on the TPS. Want to be ,67 +/- vdc closed and 4,5 vdc full open

I use the drill method but have a way of reading IAC

If you got a stock TB from junk yard for $ cheap....could do the drill mod in 1/64" increments (no more than 2-3) if buying or paying for scan of IAC becomes a cost issue.

I think I may give this a try for now and see if I can at least get the motor to actually run. Right now it is hard to start and will only run if I keep my foot on the petal about 2k RPMs.

You should not need to drill anything to get the car to idle with the stock throttle body and the CC503. If it will not idle, something else is wrong.

I suppose an A4 might pose more of a tuning challenge than an M6, but I don't think it should be having enough trouble to start drilling the throttle body. When is it having trouble? In park? In drive?
When slowing to a stop? All the time?

I would agree. I only had to drill mine out when I went 383 and bigger cam. My 350 H/C motor with stock TB was fine

Assuming there is not a mechanical issue (stuck IAC solenoid)....perhaps there is a issue with the pcm4less tune....which is not unheard of

unfortunately scan software or tool would considerably narrow down the problem but OP does not have those resources

cracking the blades open could be a way to see if the idle issue is better. Suggest OP write down the amount of turn for the TB stop screw (1/4, 1/2, etc) so he can restore that. Or at least measure TPS VDC with a DVM before and after the stop screw adjustment and use that as a compass to restore TB blade.

If a A4 car fing with the TPS will affect tranny shifting

[QUOTE=ACE1252;19587526]You should not need to drill anything to get the car to idle with the stock throttle body and the CC503. If it will not idle, something else is wrong.

^^^ What ACE says, I have NEVER had to drill a T/B, 383, 396 cu in, cams in the 250 duration + range. what you can do is get a shim and put between the T/B stop pad and tab, this would represent opening the blades, then you can see it it helps, but from your descrition, Im sure its something else, especially stating that you have to hold it at 2000 RPM's to stay running..

There possibly could be something else, but I am struggling to figure out what else it could be.

I havent even gotten the car out of the garage yet, it barely starts/runs at all so I have never put it into gear.

That is my struggle, if there were a problem with the tune, the only way I would know is to ship the PCM back to the Tuner to have him double check, but that could be a waste of time and I would have to pay for shipping twice if there is nothing wrong.

I did go ahead and adjust the stop as well as slot the TPS holes and positioned so that I got the .67 V. Unfortunately I wasnt able to measure exactly how much I changed it because I had messed with it before.

[QUOTE=moehorsepower;19588062]Since I did adjust the stop and TPS, I will see if that helps at all. I finished up last night around 10:30 but it was too late to start it up. I will do it today after work and see what we've got!

Was the car running fine before the cam work? What all was changed with the cam?

Are you 100% sure the rockers are lashed correctly?

Dude, I just saw your other thread....and I forgot that you had that voltage/cranking issue. Did you not figure out what was causing the cranking issue before changing the cam?

You might be still having current draw/voltage issues. That would cause it to do all kinds of stuff.

Is it still laboring to turn over? What are the voltage readings when cranking it? Pull the PCM fuse(fuse box inside the car), put a voltmeter on the battery, and video the reading while cranking it. I want to see what the voltage does.

If your car won't start or hold an idle there is likely a timing issue (either ignition or valvetrain) or a massive vacuum leak. I'd make sure cam is installed properly, opti installed properly, plug wires in correct order, and rockers adjusted properly before I started messing with the throttle body.

I had a CC503 and even with a stock tune it idled well enough.

Yeah the motor was running just fine before, I put in a CC503, springs, 1.6 rockers, studs, pushrods, valve covers, 160 degree thermostat, yank 3600 stall, switched from rusty pacesetter LT's to stainless LT's, solid motor mounts to poly mounts, trans cooler, maybe a few other small things. Also ended up putting in new optima battery, starter, battery cables too. I know not all related, but figured I would throw it out there.

I cant promise the rockers were lashed correctly because I did it myself and this was my first time doing it. I did read up on it and tried my best, cant remember exactly how much I turned the nut after zero lash, I would have to dig it up as that was months ago.

It is still struggling a little bit, but is much better than it was. It will crank enough to start the motor, but I guess I thought once it was running then it was fine, didnt think about how varying voltage could possibly affect other things. I did mess with it last night and identified that it is the aftermarket fuel pump wiring that is causing it. Gonna open the trap door access back up and take a look at it. Unfortunately the way the car is parked in the garage I cant open the drivers door to pull the PCM fuse. If needed I might move the car to do that.

It may be a timing thing . . . I had been looking into the TB as the tuner suggested it. I guess I will pop off the valve covers and check the lash on the rockers. I dont know how I could have installed the cam incorrectly . . . I feel confident in the opti, its an MSD that is fairly new, very low miles, and I know its lined up with the pin in the right hole as the motor was out and striped down when I did this, it was very easy to put on for once. Same thing with the wires although I have triple checked those.