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Iac steps vs effective area table

 
Old 08-06-2018, 12:33 PM
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Default Iac steps vs effective area table

How do I correct this table so the iac will work correctly. Car is heads cam Ls1 with fast 102 and nick Williams 102. Sd tune running in open loop.

Been reading up on it some but not exactly sure what to do. Do I log dynamic airflow, desired idle airflow and iac steps. Take that specific iac step cell and change low or higher so that the desired idle airflow and dynamic airflow gets close to matching? Do that for as much as I can on the table.

The main problem I have with the setup is blipping the throttle and the engine dying. Have messed with idle over speed and under speed, tried adjusting the proportional table, changed some fueling which helped the most.

It just flat out drops to nothing and will occasionally catch back up.

Im thinking part of my issue maybe where I have the throttle blade adjusted. Car wonít idle correctly at a set timing. Only idles right with over speed and under speed catching it. TPS voltage is .69 and the hot iac counts seem to stay from 80 to 110.

Car cranks and idles good but as soon as I blip throttle itís over.
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Old 08-06-2018, 06:25 PM
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Have you tried adjusting your Throttle Follower table for that?
Edit: Responded to soon without reading your whole post. I would open the throttle blade to get those counts down to 50-60 then do a TPS reset and see how it acts. You may need to lower your TPS voltage also. Read through my thread titled "Idle Airflow config?". Theres a lot of good sugestions in there.

Last edited by Monte4ever; 08-06-2018 at 06:38 PM.
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Old 08-06-2018, 07:01 PM
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Originally Posted by Monte4ever View Post
Have you tried adjusting your Throttle Follower table for that?
Edit: Responded to soon without reading your whole post. I would open the throttle blade to get those counts down to 50-60 then do a TPS reset and see how it acts. You may need to lower your TPS voltage also. Read through my thread titled "Idle Airflow config?". Theres a lot of good sugestions in there.
I havenít tried messing with the throttle follower to see if I could fix it that way although I have thought about it. I read through that thread Saturday trying to learn more about the Iac steps vs effective area table. Iíll read through it again though, I didnít pay much attention to the other ideas. I had came to the conclusion that if I corrected this table that I would be much better off.
The main reason I came to that conclusion was when we switched from an ls6 intake and stock throttle body to fast 102 and nick Williams 102 tb on my dads heads and cam car. I didnít have to really do anything but tune the ve on his with the stock tb. After the change to the 102 intake and tb it didnít wanna run very well but I half assed it and made it work a little better.
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Old 08-13-2018, 06:15 AM
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It is difficult to describe how to do this. First get your warm idle counts down to about 30. With a NW 102, this may involve drilling if you get past .67 volts. What makes it tricky is you can not log effective area, so this has to be done indirectly.

Log desired idle air vs iac counts
Log dynamic air vs iac counts. Same log, just a different histogram.

Copy both into excel
Copy your effective area table into excel

Then, for a specific effective area, look up the counts, find the dynamic air that matches those counts. Then, use the desired air that matches the dynamic air and find the counts for the desired air and key that into the effective area.

Confused yet?

Example: 44 sq mm area IAC is 100. When IAC is 100, desired air is 12, dynamic air is 16 g/sec. when dynamic air is 12, iac is 36. Key 36 into the 44 sq mm cell.

Rinse and repeat. A lot. After 1-3 logs it should be close enough to help with stability. Typically after the first log there is a notable improvement.

Hope that makes sense. And helps.
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Old 08-13-2018, 06:44 PM
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Originally Posted by Darth_V8r View Post
It is difficult to describe how to do this. First get your warm idle counts down to about 30. With a NW 102, this may involve drilling if you get past .67 volts. What makes it tricky is you can not log effective area, so this has to be done indirectly.

Log desired idle air vs iac counts
Log dynamic air vs iac counts. Same log, just a different histogram.

Copy both into excel
Copy your effective area table into excel

Then, for a specific effective area, look up the counts, find the dynamic air that matches those counts. Then, use the desired air that matches the dynamic air and find the counts for the desired air and key that into the effective area.

Confused yet?

Example: 44 sq mm area IAC is 100. When IAC is 100, desired air is 12, dynamic air is 16 g/sec. when dynamic air is 12, iac is 36. Key 36 into the 44 sq mm cell.

Rinse and repeat. A lot. After 1-3 logs it should be close enough to help with stability. Typically after the first log there is a notable improvement.

Hope that makes sense. And helps.
Took me several times reading it over but I got it lol. I really appreciate the info. I gotta get the wot tuning done for the track this Saturday before I try to adjust it. The race in Ohio is the next weekend so itís gotta be track ready by then.
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Old 08-13-2018, 07:44 PM
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Darth_V8r is the man when it comes to getting that effective area table in line.
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Old 08-13-2018, 08:57 PM
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Knowing something is one thing. Not being afraid to share it is another, and Darth does BOTH right here fairly often! Thank you Darth!
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Old 08-13-2018, 09:40 PM
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He has some good info, thatís for sure.
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