Dropped the idle
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6th Gear
Joined: Nov 2006
Posts: 13
Likes: 0
Dropped the idle
After reading thru the SERT manual I am a bit confused as to how the IAC steps actually impact my idle - so I did a couple tests.
First test - I lowered my disired idle speed and logged the idle to ensure I was in the correct temp range.
Result - The idle fell to where it was programmed and the engine ran fine.
Second test - In addition to lowered disired idle I lowered the IAC steps across the board by about 7 to 10 steps.
Result - No change
So what does the IAC steps actually do?
Video of bike at idle...
http://s41.photobucket.com/albums/e2...v?t=1169168392
I've read on here that lowering the idle is a bad idea due to lower oil pressure. I understand the thoery, but what's the difference between my bike and all the carb'd bikes I see chugging at like 650rpm? I dropped mine to 832 with sert and really like how it sounds...can I keep it?
First test - I lowered my disired idle speed and logged the idle to ensure I was in the correct temp range.
Result - The idle fell to where it was programmed and the engine ran fine.
Second test - In addition to lowered disired idle I lowered the IAC steps across the board by about 7 to 10 steps.
Result - No change
So what does the IAC steps actually do?
Video of bike at idle...
http://s41.photobucket.com/albums/e2...v?t=1169168392
I've read on here that lowering the idle is a bad idea due to lower oil pressure. I understand the thoery, but what's the difference between my bike and all the carb'd bikes I see chugging at like 650rpm? I dropped mine to 832 with sert and really like how it sounds...can I keep it?
Intermediate
Joined: Oct 2005
Posts: 49
Likes: 0
From:
RE: Dropped the idle
Yeah, I heard the same thing about the oil pressure, but when the engine sarts to overheat
the idle will drop to 800 rpm. So what's the difference? I've had mine set like that for a year
now. No problems to date......I say enjoy it.
[IMG]local://upfiles/5396/10F40D9E2B644C92A3168A829297E71F.jpg[/IMG]
the idle will drop to 800 rpm. So what's the difference? I've had mine set like that for a year
now. No problems to date......I say enjoy it.
[IMG]local://upfiles/5396/10F40D9E2B644C92A3168A829297E71F.jpg[/IMG]
Road Master
Joined: Mar 2006
Posts: 1,037
Likes: 2
From: Winslow, Arizona
RE: Dropped the idle
I think the biggest problem with dropping the idle on FI bikes is whether the charging system can keep up with the increased electrical needs of an FI bike compared to a carbed bike.
Outstanding HDF Member
Joined: Apr 2006
Posts: 2,537
Likes: 21
RE: Dropped the idle
The IAC (Idle Air Controller) is a Computer controlled Enrichener/Choke....
The Stepper motor goes through it's cycle when you power-up the bike, and is set in place by the Atmospheric sensor data.....
It controls the amount of air into the TB unit by use of an electrically operated pintle......
Less air in (More steps), richer fuel mixture......
As the motor warms up, the stepper unit decreases as it opens up to allow more air into the unit, requiring less fuel to create an adequate engine temp....
As far as the idle...
Look, it's your bike, but it is best for the motor to idle at the 950-1050 rpm zone..... Better warm ups, better throttle response from off idle, complete and thorough combustion, adequate oil flow.....
The Stepper motor goes through it's cycle when you power-up the bike, and is set in place by the Atmospheric sensor data.....
It controls the amount of air into the TB unit by use of an electrically operated pintle......
Less air in (More steps), richer fuel mixture......
As the motor warms up, the stepper unit decreases as it opens up to allow more air into the unit, requiring less fuel to create an adequate engine temp....
As far as the idle...
Look, it's your bike, but it is best for the motor to idle at the 950-1050 rpm zone..... Better warm ups, better throttle response from off idle, complete and thorough combustion, adequate oil flow.....
Tourer
Joined: Oct 2006
Posts: 422
Likes: 0
From:
RE: Dropped the idle
Correct me if I'm wrong: Once the engine is up to temp the "IAC Warm up Steps " table is ignored.
The IAC allows air to by pass the throttlevalve (plate). If the motor falls below preset RPM it opens the Pintel allowing more air to flow around the throttle valve. If it is above the preset RPM it closes to reduce the amount of air bypassing the throttlevalve. If you have the throttle valve stopnot adjusted correctlyyou could force the IAC to its travel limitrendering it ineffective.
Is there a recommended IAC position (steps) once the engineis up to temp? It would need to be at the lower end to allow enough travel for cold startup? (For what ever reason the IAC part of the manual does not display correctly on my PC)
The IAC allows air to by pass the throttlevalve (plate). If the motor falls below preset RPM it opens the Pintel allowing more air to flow around the throttle valve. If it is above the preset RPM it closes to reduce the amount of air bypassing the throttlevalve. If you have the throttle valve stopnot adjusted correctlyyou could force the IAC to its travel limitrendering it ineffective.
Is there a recommended IAC position (steps) once the engineis up to temp? It would need to be at the lower end to allow enough travel for cold startup? (For what ever reason the IAC part of the manual does not display correctly on my PC)
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Road Warrior
Joined: Oct 2006
Posts: 1,331
Likes: 4
From: South Jersey, AC area
RE: Dropped the idle
I have my idle set to 975 rpm, I wanted it a little lower that the factory setting.[8D]
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Joe Kucinski
Outstanding HDF Member
Joined: Apr 2006
Posts: 2,537
Likes: 21
RE: Dropped the idle
Once the engine is up to temp the "IAC Warm up Steps " table is ignored.
The IAC allows air to by pass the throttlevalve (plate). If the motor falls below preset RPM it opens the Pintel allowing more air to flow around the throttle valve. If it is above the preset RPM it closes to reduce the amount of air bypassing the throttlevalve. If you have the throttle valve stopnot adjusted correctlyyou could force the IAC to its travel limitrendering it ineffective.
Is there a recommended IAC position (steps) once the engineis up to temp? It would need to be at the lower end to allow enough travel for cold startup? (For what ever reason the IAC part of the manual does not display correctly on my PC)
The IAC allows air to by pass the throttlevalve (plate). If the motor falls below preset RPM it opens the Pintel allowing more air to flow around the throttle valve. If it is above the preset RPM it closes to reduce the amount of air bypassing the throttlevalve. If you have the throttle valve stopnot adjusted correctlyyou could force the IAC to its travel limitrendering it ineffective.
Is there a recommended IAC position (steps) once the engineis up to temp? It would need to be at the lower end to allow enough travel for cold startup? (For what ever reason the IAC part of the manual does not display correctly on my PC)
In the SERT Table, even at 280 deg F, as an example, in a map that I am looking at (129nk012), the IAC has 10 steps, and this is for start up at operating temp.....
Once the Startup fuel has cycled out, the IAC will go down to zero steps.....
But remember, IAC and Startup Fuel are modifiable, as the motors needs arise..... Maybe you have a 53 mm HPI TBI, you are going to adjust the IAC and Startup fuel to compensate for the larger TB unit and possibly larger injectors (If you really wanted to)....
IAC position is ZERO at operating temp (260 deg F), after the bike has been running.....
Banned
Joined: Jul 2006
Posts: 866
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From:
RE: Dropped the idle
IAC position as reported by data will most likely be in the 30-40 step range. If bike is idling at 1000 rpm and data shows no steps you either have a stuck IAC or an intake leak
IAC per the IAC warmup table will be done.
Altering the Desired Idle table changes the IAC (metered air bypass - how delphi controls idle) all the time
Altering the IAC WARMUP table is only during warmup - it's for additional idle control during warmup on some combinations - like SHB indicated.
IAC per the IAC warmup table will be done.
Altering the Desired Idle table changes the IAC (metered air bypass - how delphi controls idle) all the time
Altering the IAC WARMUP table is only during warmup - it's for additional idle control during warmup on some combinations - like SHB indicated.