Getting IAC counts down
10-22-2007, 09:13 PM
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Getting IAC counts down What are the options available to get the IAC down to a respectable level? I see 2 options via searching:
1) Adjust set screw to crack the blade open slightly
2) Drill the TB
What is 3)? I want to make sure I'm not missing anything since I see some thoughts around "you should not ever have to drill a TB."
I have been working on my idle quite extensively over the past couple of days and with the help of a few people have the car to the point where it isn't dying. My IAC counts are still waaaay high though (staying over 150).
I have already adjusted the set screw to where I can't get the TPS to reset to 0% if I go more. I played and played with the base running airflow and finally am at a point where it will continue to run, I'm not sure if I need to keep fighting that in an attempt to work the IAC down or if there are other options.
Thoughts?
Current tune/log/specs of car are here if interested:
https://ls1tech.com/forums/pcm-diagnostics-tuning/802700-maf-effects-idle-tuning.html
1) Adjust set screw to crack the blade open slightly
2) Drill the TB
What is 3)? I want to make sure I'm not missing anything since I see some thoughts around "you should not ever have to drill a TB."
I have been working on my idle quite extensively over the past couple of days and with the help of a few people have the car to the point where it isn't dying. My IAC counts are still waaaay high though (staying over 150).
I have already adjusted the set screw to where I can't get the TPS to reset to 0% if I go more. I played and played with the base running airflow and finally am at a point where it will continue to run, I'm not sure if I need to keep fighting that in an attempt to work the IAC down or if there are other options.
Thoughts?
Current tune/log/specs of car are here if interested:
https://ls1tech.com/forums/pcm-diagnostics-tuning/802700-maf-effects-idle-tuning.html
10-22-2007, 09:35 PM
#2
You need to drill the throttle blade. Theres no way around it. You need to get the motor more air. how ya gonna do that without;
A: cracking the blade open more, or,
B: drilling a hole in the throttle body.
Also, how are you trying to tune your VE table? you havent done much of anything other that putting a dip in it where it idles. It needs alot more work, in and around idle to make it act right.
Are you using a wideband? Do you know how to use the histogram?
You need to go back to SD and get the VE table straight. Turn the maf back off and leave it off til it runs perfect in SD.
A: cracking the blade open more, or,
B: drilling a hole in the throttle body.
Also, how are you trying to tune your VE table? you havent done much of anything other that putting a dip in it where it idles. It needs alot more work, in and around idle to make it act right.
Are you using a wideband? Do you know how to use the histogram?
You need to go back to SD and get the VE table straight. Turn the maf back off and leave it off til it runs perfect in SD.
10-22-2007, 10:11 PM
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I haven't been able to do a whole heck of a lot with the VE as it has been raining - I will be working on it tomorrow though. What I have so far was determined by trying to extrapolate information from some other people's tunes - maybe not the best method but it got me started.
I have a wideband - I understand how to go through and log in SD, using the AFR error and use that information from the histogram to adjust the VE table. The MAF is off right now (if the tune in the thread I pointed you too shows it as being on I upped the wrong one, been through a ton today).
I was under the assumption that drilling was my next step, I am just at the point of confusing myself with everything I'm trying to learn at this point. I don't really want to just use this or that because someone said to, I'm trying to understand how and why.
The biggest question I have right now (and what got me thinking there may be something else to the IAC counts than jumping in with a drill bit), is all of the changes that I have made to the base airflow. It took massive amounts of trial and error, and eventually some advice from Mike at Straightline to get that in line enough to run. I'm still not convinced that I am "perfect" from that standpoint...
Reading and learning is all good, and I enjoy it - but I'm the type that has to see it in person to grasp it. This being the first car I've tuned (yea yea, smart thing, go from stock and never tuning to trying to tackle a 402
), it is definitely a huge learning curve. I appreciate all the help.
I have a wideband - I understand how to go through and log in SD, using the AFR error and use that information from the histogram to adjust the VE table. The MAF is off right now (if the tune in the thread I pointed you too shows it as being on I upped the wrong one, been through a ton today).
I was under the assumption that drilling was my next step, I am just at the point of confusing myself with everything I'm trying to learn at this point. I don't really want to just use this or that because someone said to, I'm trying to understand how and why.
The biggest question I have right now (and what got me thinking there may be something else to the IAC counts than jumping in with a drill bit), is all of the changes that I have made to the base airflow. It took massive amounts of trial and error, and eventually some advice from Mike at Straightline to get that in line enough to run. I'm still not convinced that I am "perfect" from that standpoint...
Reading and learning is all good, and I enjoy it - but I'm the type that has to see it in person to grasp it. This being the first car I've tuned (yea yea, smart thing, go from stock and never tuning to trying to tackle a 402
), it is definitely a huge learning curve. I appreciate all the help.
10-23-2007, 08:58 AM
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3) is idle fueling and spark advance. Just like shade tree you
want to tune to max vacuum meaning min MAP and IAC counts.
This happens when motor is at peak idle efficiency. A monster
cam makes efficiency suck down low.
I wouldn't fixate on the idle counts, as long as your airflow is
linear with IAC; on an F-body you have plenty of room left at
150 IAC though starting wants alll it can get. The bigger the
motor the more air it needs, period, and the bigger the cam
the more wasteful of available air it will be.
What you don't want, is to be high IAC counts and nothing
comes of it (like pink line on chart, caused by too small an
IAC port). Nor drill so big a hole that IAC ever swings within
touching distance of zero.
want to tune to max vacuum meaning min MAP and IAC counts.
This happens when motor is at peak idle efficiency. A monster
cam makes efficiency suck down low.
I wouldn't fixate on the idle counts, as long as your airflow is
linear with IAC; on an F-body you have plenty of room left at
150 IAC though starting wants alll it can get. The bigger the
motor the more air it needs, period, and the bigger the cam
the more wasteful of available air it will be.
What you don't want, is to be high IAC counts and nothing
comes of it (like pink line on chart, caused by too small an
IAC port). Nor drill so big a hole that IAC ever swings within
touching distance of zero.
