can't get IAC counts down
03-28-2004, 03:18 PM
#1
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Join Date: Oct 1999
Location: Maryland
Posts: 159
can't get IAC counts down
I am having an idling problem with my 94 Z28, I just got finished with the rebuild. It has a CC 306 cam and an LT4 top end. with Hooker LT's and more.
I scanned it today and my IAC counts were running in the high 90's, I tried turning the Idle screw down but that didn't help much so I drilled out the IAC passage hole to 11/64 and tried again. This helped alittle, it set it at 88 while idling. This is with the stock MAF ends. I used to have ported ones but I heard that they are problematic.
It is acting strange, when I first start it, it idles where it is supposed to (programed to 800), If I wait for it to go into closed loop before driving it the idle stays the same. If I drive it reguardless of waiting for it to change loops or not, when I come to a stop the idle drops to around 350 to 400 and sometimes stalls out. What do I need to do to fix this???
Also my BLMS are alittle low, they are sitting around 116ish, sometimes lower. What do I need to do to fix this??
Any help is appreciated
Thanks
John
I scanned it today and my IAC counts were running in the high 90's, I tried turning the Idle screw down but that didn't help much so I drilled out the IAC passage hole to 11/64 and tried again. This helped alittle, it set it at 88 while idling. This is with the stock MAF ends. I used to have ported ones but I heard that they are problematic.
It is acting strange, when I first start it, it idles where it is supposed to (programed to 800), If I wait for it to go into closed loop before driving it the idle stays the same. If I drive it reguardless of waiting for it to change loops or not, when I come to a stop the idle drops to around 350 to 400 and sometimes stalls out. What do I need to do to fix this???
Also my BLMS are alittle low, they are sitting around 116ish, sometimes lower. What do I need to do to fix this??
Any help is appreciated
Thanks
John
03-28-2004, 06:20 PM
#2
Registered User
Join Date: Feb 2002
Location: Toledo, Ohio USA
Posts: 1,107
I'm not a programming genious, but I think you have to change a little more than 'Target Idle' in order to keep it running with a bigger cam.
When it stalls out while driving in Open Loop it sounds like your BLMs need to relearn. How long have you drove it?
May have to adjust the boundries of your BLM Cells(Common with bigger cams). Because if you have a target idle that's higher than your lowest RPM Cell, then that renders that cell useless, changing the value will put those back into use.
This might explain why sometimes it stalls when the car comes to a stop, it goes into that lowest BLM Cell that is RARELY entered and takes a crap because it hasn't "learned".
Did you change the Closed TPS Spark Advance tables yet? Try upping the advance some.
Example:
On a XE244/230 Cam:
RPM/Advance
400:27.0
800:27.0
1200:27.0
1600:34.0
2000:40.0
This is what I've learned looking at other tunes. Try that.
Or maybe altering the IAC Target RPM vs. Coolant, remember to keep your A/C off when trying correcting that pesky IAC.
When it stalls out while driving in Open Loop it sounds like your BLMs need to relearn. How long have you drove it?
May have to adjust the boundries of your BLM Cells(Common with bigger cams). Because if you have a target idle that's higher than your lowest RPM Cell, then that renders that cell useless, changing the value will put those back into use.
This might explain why sometimes it stalls when the car comes to a stop, it goes into that lowest BLM Cell that is RARELY entered and takes a crap because it hasn't "learned".
Did you change the Closed TPS Spark Advance tables yet? Try upping the advance some.
Example:
On a XE244/230 Cam:
RPM/Advance
400:27.0
800:27.0
1200:27.0
1600:34.0
2000:40.0
This is what I've learned looking at other tunes. Try that.
Or maybe altering the IAC Target RPM vs. Coolant, remember to keep your A/C off when trying correcting that pesky IAC.
Last edited by ZPaul2Fresh8; 03-28-2004 at 06:29 PM.
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