NO CATZZ

iTrader: (10)

Just finished my motor rebuild and I am having trouble getting it to idle. ATAP shows 0 for IAC counts. Been searching for vacuum leaks(pulls 23 inches when I nurse it into a steady idle) but I can't seem to find any. Swapped IAC motors and same results.

One thing to note: I have the Holley 'heatsoak' intake manifold and homemade gaskets. I already heat cycled the motor 3 times and retorqued everything. TB hole is drilled to 13/64 and is ported.

Please give me some advice.

Thanks
Josh

Colonel

Any codes? And does the IAC stay dead on zero all the time? What happens if you plug the TB hole?

Dave Carney

Do you have Edit? Who tuned it? Sounds like they were set to zero my mistake during the tune. Is it the same in gear as in park? There's a setting for each in Edit.

Y2KSS

iTrader: (2)

I just had a 02 silverado in our shop doing the same thing. At idle it had 0 counts but everthing was fine off idle. The intake gaskets were leaking on the driver side. Also, the truck was setting no codes.

NO CATZZ

iTrader: (10)

Here are the codes that I have:

P0405 EGR Low Voltage(removed EGR and haven't turned the code off yet)
P1637 Generator L-Terminal Circuit(?? never seen this before)
P0108 MAP Circuit Hi(did not through this one first 2 times I fired it up)

And yes, the IAC counts stay at 0...even with the hole plugged.

Thanks for the quick response...any suggestions?

Josh

NO CATZZ

iTrader: (10)

Yes I have edit...and I am the only one that has ever tuned it(so if it is messed up it is all my fault).

Here is what I have done in edit for idle characteristics:

Idle speed: 900
IAC Park: all points from 40C and up to 21
Idle air in gear: all points from 60C and up to 8.6
Main VE: 400rpm * 60%
800rpm * 80%
1000rpm * 90%

Colonel

It stays at zero even when not at idle? If that's the case (and the fact that you haven't set an IAC DTC) then it sounds like you got the version of Autotap that does that. I've heard of this several times. Or, somebody really mucked up the PCM tuning.

JimMueller

iTrader: (9)

I have the same problem with AutoTap 2.04 for Windows. If I switch to the DOS version the IAC's behave normally.

NO CATZZ

iTrader: (10)

Well, the tuning should not be 'mucked' up because I tried to run the same program that I had in it before. Figured it would be close(my cam is a little bigger now) because it ran fine before the rebuild.

I have never used ATAP in DOS, how do you set that up? I am a point and click kinda guy so I don't use DOS much at all. I don't remember what version I have and my laptop is at the shop.

Thanks for your inputs.

Josh

EFILive

iTrader: (2)

If you can't log the IAC you could try logging Desired IAC PID?

The Desired IAC PID is what the PCM wants the IAC to be.

The IAC will almost always match the Desired IAC and when it differs it is only because it takes the PCM a finite amount of time to "move" the IAC position to match the Desired IAC position.

Regards
Paul

P.S. If you have an AutoTap interface you can download EFILive V5 (free) and log up to 5 seconds of data - that will show you if your IAC is ok or not. EFILive will og the IAC correctly.

Brains

iTrader: (7)

the Windoze version of Autotap doesn't report the IAC .. Any time I want to view it, I'm forced to fire up the DOS version

I wish I wasn't so broke right now, I have used and LOVE Paul's software -- I'll will definitely pick it up once I get back into a job (damned mortgage gets in the way of my car mod budget).

NO CATZZ

iTrader: (10)

UPDATE

Used 5 seconds of EFI Live this morning and my IAC counts are maxed out!! Talk about going from one extreme to the other.

Like I mentioned before my TB hole is at 13/64 right now...should I go bigger? I really need this thing to idle cause I want to go for a drive. This project has taken me 8 months to complete. I tore it down, rebuilt everything, installed some Absolute Stage II heads with nice cam, stabbed the motor back in(that was 4 months) then got deployed for 4 more months...now I am back and so close to being done I can taste it.

Please Help

Colonel

IMO, you should get the DOS version of Autotap. It's all I've ever used and I've never had any of the problems I've seen with the Windows version.

If your IAC is truly maxed out, try this before drilling (a little known trick that I've learned.)

1. Open the throttle blade up with the idle set screw by a few degrees as measured with Autotap.

2. Turn the ignition on and unplug the TPS sensor.

3. Turn the ignition off, and then back on.

4. Plug the TPS back up.

5. Your TPS should now read zero or close to zero.

This does the same thing as drilling a hole in your TB.

If it doesn't bring the IAC down enough, repeat.

NO CATZZ

iTrader: (10)

DOH! I wish I would have known that about an hour and a half ago. I went ahead and drilled TB hole out to 1/4 and it worked. It idles fine now, hot starts fire right up only thing is idle down is a little slow now. Took it for a drive(6 miles I needed gas bad) now I am going to pull the codes, check the plugs, check for leaks....then I am going data log for about 20 miles.

I have other TB's at my disposal so if my idle down doesn't suite me I will try the reset procedure.

Thanks for all of your help Stephen as well as all the other people that chimed in.

Woo Hoo!! The HotRod lives again!

Josh

NO CATZZ

iTrader: (10)

DTC's

P0405 EGR
P0121 Throttle Position Sensor Performance(?)

Got any ideas on this one Stephen?

This is all I got on my 6 mile drive...not bad for shade tree mechanic on his first LS1 rebuild.

Thanks
Josh

Colonel

Well, you already know how to fix the EGR code. Turn it off.

The TPS code...does the TPS appear to be functioning properly? Goes to zero (or at least below 1%) when you let off and goes to 100% when you mash it to the floor? The readings seem smooth in between when you slowly take it through it's range?

rwb

I'm getting the same trouble code, and yes I've done all of that and I still get the PO121. It goes smoothly through its range on Autotap. 0% to 100%
Any help would be appreciated.

Colonel

If you can get your hands on a new TPS, that would surely help to narrow it down.

I might also try reseting the TPS as I described as well as resetting the PCM.

rwb

I put a new TPS in and did all of the resetting, still the same thing. It constantly surges and hunts for a continueus idle. Left just idling it will die. No other codes just PO121.

WicketMike

iTrader: (13)

anybody find a fix for this code?