SAFC2 for a idle on a sti

Turbojunkie · Jan 30, 2006, 11:41 AM

i know i know, this is a evo forum. I dont have a account on nosiac. Im trying to help a friend so bear with me please. We have everything ok and set up but the problem is the idle. we just installed 816cc injectors and the lowest NE01 will go on the afc is 800 rpm. his car idles at 500-600 rpm. is their another way with afc to get the idle go work out. anyhelp would be great. thanx

PVD04 · Jan 30, 2006, 11:57 AM

Whatever settings you put in for 800 RPM should carry down to 0.

-Paul

Turbojunkie · Jan 30, 2006, 12:04 PM

Quote:

Originally Posted by PVD04

Whatever settings you put in for 800 RPM should carry down to 0.

-Paul

I not 100% sure on this, but i think the ne01 reads from 800 (or what ever) to the setting on ne02. then the setting for ne02 reads to neo3, and so on. so i have no way to correct for under 800 rpm. I thought maybe i was missing a setting in the afc somewhere where you can set the idle different from the rest of the imputs.

GPTourer · Jan 30, 2006, 12:24 PM

Quote:

Originally Posted by PVD04

Whatever settings you put in for 800 RPM should carry down to 0.

-Paul

Exactly. That piddly 200-300RPM difference at idle is not going to make much of a differene. It'll use the ne01 setting and the computer will adjust for the rest.

Turbojunkie · Jan 30, 2006, 12:41 PM

For reason his is not compensating at idle. it bogs real bad and dies. I know our cars are set karmen and theirs are hotwire. maybe its a setting in their. so we should be able to get idle correction with the ne01 pulled out? ill give it another shot. thanx

GPTourer · Jan 30, 2006, 01:02 PM

500-600 sounds too low anyway. He should just adjust whatever his idle is up to like 900 or so. 816cc's might just be too big for an SAFC2. What injectors did the car come stock with?

PVD04 · Jan 30, 2006, 01:24 PM

The way the SAFC works is for RPMs between the set points it interpolates the two closes numbers. For example, if you had 800 RPM set to -20 and 1200 RPM set to -10, 1000 RPM would be -15. At the ends it just carries whatever setting you have as far as you go beyond it. So if you set 800 to -20, everything below 800 is set to -20. And if your highest point is 7000, everything above 7000 RPM will use that same setting. If lowering the 800 RPM set point does not fix the idle, then the injectors may be too big to be adjusted for with the SAFC-II. Stock ECUs typically do not like idle airflow readings that are too low.

-Paul

slo4g63 · Jan 30, 2006, 01:29 PM

I would contact Dan from Godspeed, he has helped me in the past with an STI and is pretty well-known on NASIOC.

Good Luck

Turbojunkie · Jan 30, 2006, 08:15 PM

Quote:

Originally Posted by slo4g63

I would contact Dan from Godspeed, he has helped me in the past with an STI and is pretty well-known on NASIOC.

Good Luck

thank you, i will definatly do that.

Turbojunkie · Jan 30, 2006, 08:18 PM

Quote:

Originally Posted by GPTourer

500-600 sounds too low anyway. He should just adjust whatever his idle is up to like 900 or so. 816cc's might just be too big for an SAFC2. What injectors did the car come stock with?

sti's idle that low. hes running a g12 so he needs at least 816's. 2.5l takes it fine.

jj_008 · Jan 30, 2006, 08:25 PM

Does he have a wideband? If so, take as much fuel out as you can at (800rpm) in order to idle around 14.7. Then you can compensate at the next RPM increment. 816cc injectors are really moving some fuel at idle.

GPTourer · Jan 30, 2006, 08:34 PM

Quote:

Originally Posted by Turbojunkie

sti's idle that low. hes running a g12 so he needs at least 816's. 2.5l takes it fine.

Having 2.5L's does not change the fact that an SAFC2 is too blunt an instrument to fine tune for 816's for daily drivability. Having a G12, or whatever big turbo, means nothing when you are trying to pull vacuum and idle. It may scream when he is at WOT, but obviously that's not the problem. Sounds like he needs something to adjust the pulsewidths and deadtime for lower RPM's, something a SAFC2 can not do. A stock STi may idle that low and be fine, but this one isn't.

BJai02 · Feb 1, 2006, 10:08 AM

Is 816 a common injector sizes being used in STi's? It sounds a bit big... the OEM injector driver may not be good enough to get a good pulse. Aftermarket ECU like Autronic and AEM has better injector drivers to work with huge injectors. To compensate for it, raising the idling speed will help.

heyzeus11 · Feb 3, 2006, 11:01 PM

at part throttle what is his cars afr? is it holding around ~14.7. Maybe your friend has a vacuum leak(not boost leak); tell him to check intake piping between the maf and throttle body. Most ecus should always maintain around 14.7 afr on its on regardless of injector size; but who knows with those ugly looking engines

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