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Turbo98



Posts : 28
Join date : 2013-02-23

PostSubject: Basic Strategy Question   Sun Sep 01, 2013 5:14 pm

What dictates which contoller does the fine tuning of the idle? I've noticed that sometimes the timing is bouncing up and down and the IAC duty cycle is steady. Then after revvving it for example and it comes back down, things seem to be switched-the IAC duty cycle is bouncing up and down and the timing is steady. All the engine parameters look to be the same (temp, a/f, IAT, etc...). So I'm kind of wondering what the strategy of the ECU is in determining which has more precedence and why?
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ip-alpha
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Posts : 48
Join date : 2013-05-29
Location : Tampa, Florida

PostSubject: Re: Basic Strategy Question   Tue Sep 03, 2013 10:55 am

Turbo98 wrote:
What dictates which contoller does the fine tuning of the idle? I've noticed that sometimes the timing is bouncing up and down and the IAC duty cycle is steady. Then after revvving it for example and it comes back down, things seem to be switched-the IAC duty cycle is bouncing up and down and the timing is steady. All the engine parameters look to be the same (temp, a/f, IAT, etc...). So I'm kind of wondering what the strategy of the ECU is in determining which has more precedence and why?
It uses both. I tune idle in these steps

- VE/Target table
- Ignition table
- Idle offsets
- Idle spark
- Idle feedback
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Turbo98



Posts : 28
Join date : 2013-02-23

PostSubject: Re: Basic Strategy Question   Wed Sep 04, 2013 6:11 am

ip-alpha wrote:
Turbo98 wrote:
What dictates which contoller does the fine tuning of the idle? I've noticed that sometimes the timing is bouncing up and down and the IAC duty cycle is steady. Then after revvving it for example and it comes back down, things seem to be switched-the IAC duty cycle is bouncing up and down and the timing is steady. All the engine parameters look to be the same (temp, a/f, IAT, etc...). So I'm kind of wondering what the strategy of the ECU is in determining which has more precedence and why?
It uses both. I tune idle in these steps

- VE/Target table
- Ignition table
- Idle offsets
- Idle spark
- Idle feedback
Thanks.

Iím still trying to understand more of the strategy behind how the ECU decides on which to use more often. Reason being is the real world example I listed above. After starting it and the idle settles until warm, the IAC duty cycle is relatively steady and the spark is jumping arounbd as it should. Then if I rev it to say 1500 and let it settle back down, the IAC is now jumping all over the place and the spark Is nearly steady. The idle is more choppy this way. Basically itís idling smooth and 10 seconds later, itís more choppy. All engine parameters appear to be the same (coolant, a/f, IAT, etc.). So how to I ďmakeĒ the ECU behave so it will idle the engine like before I rev it?? Anyu clues??
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ip-alpha
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Posts : 48
Join date : 2013-05-29
Location : Tampa, Florida

PostSubject: Re: Basic Strategy Question   Mon Sep 09, 2013 1:50 pm

Turbo98 wrote:
ip-alpha wrote:
Turbo98 wrote:
What dictates which contoller does the fine tuning of the idle? I've noticed that sometimes the timing is bouncing up and down and the IAC duty cycle is steady. Then after revvving it for example and it comes back down, things seem to be switched-the IAC duty cycle is bouncing up and down and the timing is steady. All the engine parameters look to be the same (temp, a/f, IAT, etc...). So I'm kind of wondering what the strategy of the ECU is in determining which has more precedence and why?
It uses both. I tune idle in these steps

- VE/Target table
- Ignition table
- Idle offsets
- Idle spark
- Idle feedback
Thanks. †

Iím still trying to understand more of the strategy behind how the ECU decides on which to use more often. †Reason being is the real world example I listed above. †After starting it and the idle settles until warm, the IAC duty cycle is relatively steady and the spark is jumping arounbd as it should. †Then if I rev it to say 1500 and let it settle back down, the IAC is now jumping all over the place and the spark Is nearly steady. †The idle is more choppy this way. †Basically itís idling smooth and 10 seconds later, itís more choppy. †All engine parameters appear to be the same (coolant, a/f, IAT, etc.). †So how to I ďmakeĒ the ECU behave so it will idle the engine like before I rev it?? †Anyu clues??
You need to work on the air:fuel, ignition timing, iac pid's and o2 feedback pid's. Sounds like it's too lean and the o2 feedback and/or iac feedback is going crazy.
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