Biss/Sas adjustment
Jul 30, 2018, 06:09 PM
#1
Biss/Sas adjustment
Hey guys, ive searched and get different answers in all threads. Im having some idle issues and have been trying to set the base idle with biss screw via evoscan adjustment. I have the desired idle on evoscan set to 945. When setting the idle with the biss screw after locking iscv through evoscan, do i set it to the factory 800 rpms or the 945 rpm i have the ecu set to?
Jul 30, 2018, 11:08 PM
#2
Evolving Member
Stop the idle stepper using Evoscan and set the idle as near below 945 rpm as possible, so the idle stepper motor has less to work with. Set the idle stepper mode off and let it idle 15 min or more (can't remember exactly) , so the idle stepper learns to keep 945 rpm. You can log the isc steps on Evoscan.
Jul 31, 2018, 08:34 AM
#3
EvoM Guru
iTrader: (1)
Setting the BISS to slightly above target idle helps to make sure the car never stumbles when returning to idle. Since your target idle is 945, set the BISS for 980-1000.
Jul 31, 2018, 08:41 AM
#4
EvoM Community Team Leader
When you use evoscan to lock the ISC does it move to a specific step # like what you have in the "Desired ISCV Initial Step..." table or some other arbitrary position? It's Something I have been wondering about.
Jul 31, 2018, 08:56 AM
#5
It’s supposed to lock it at your desired initial step. So I’m supposed to set it according to what I have my idle set at then. The way I keep the car from stumbling is set the desired initial steps in drive above the neutral steps so when you come to a stop it doesn’t stumble. What happens is the initial steps in drive disactivates when you reach 3 - 5mph and car won’t stumble.
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Biggiesacks (Jul 31, 2018)
Jul 31, 2018, 10:57 AM
#6
EvoM Community Team Leader
It’s supposed to lock it at your desired initial step. So I’m supposed to set it according to what I have my idle set at then. The way I keep the car from stumbling is set the desired initial steps in drive above the neutral steps so when you come to a stop it doesn’t stumble. What happens is the initial steps in drive disactivates when you reach 3 - 5mph and car won’t stumble.
Jul 31, 2018, 11:16 AM
#7
I’ve been reading all I can find on this and according to some threads on this it’ll lock it at the initial step and then you set your base idle. The demand % plus your initial step is where the steps should be according to the lookup table. Now my steps do whatever the hell they want so my idle will surge a little bit and it’s driving me nuts.
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Aug 1, 2018, 11:56 AM
#8
Evolving Member
Aug 1, 2018, 04:22 PM
#10
EvoM Guru
iTrader: (1)
Need to lower the ISCV stepper position tables then. If it doesn't surge in SAS mode, the ISCV is causing the surge, not the biss setting.
Also, IIRC, your car has cams. It's much easier to get cams to idle at around 1100rpms..
Also, IIRC, your car has cams. It's much easier to get cams to idle at around 1100rpms..
Aug 1, 2018, 04:41 PM
#11
So if it surges with the sas active its the iscv stepper table? Which table the initial iscv step position or lookup table? My car surges with the sas active and at idle itll surge a bit. I cant figure it out for the life of me. Ive tried the timing stability control table and nothing. afr hunts up and down and idle will slowly surge here and there. Its driving me nuts. I have the idle set for 950 rpm. I hate the high idle. It should be able to idle fine here. Ive seen videos of cars with s2's that idle great and has the loby idle which i like. My timing is set to 14 and im on 9417. If you have any advice please tell me because im about to take a ****ing hammer to it. I can post a video of it running so you can see and a log if it helps.
Aug 1, 2018, 04:48 PM
#12
EvoM Guru
iTrader: (1)
You should only have 7-8* of timing at idle, 14* is part of your surfing issue. And the car should have plenty of lope even with an 1100rpm idle.
Aug 1, 2018, 05:20 PM
#13
7 - 8 seems very low. I tried lowering it to 13 and engine speed was pretty low. It just seemed to like 14. I also read tscomp and i think john bradley said they like running them at higher timing. But i can give it a try for sure. I know more timing and leaner afr causes surge but i thought 14* was pretty acceptable.
Aug 1, 2018, 06:24 PM
#14
EvoM Guru
iTrader: (1)
Originally Posted by nor11384
7 - 8 seems very low. I tried lowering it to 13 and engine speed was pretty low. It just seemed to like 14. I also read tscomp and i think john bradley said they like running them at higher timing. But i can give it a try for sure. I know more timing and leaner afr causes surge but i thought 14* was pretty acceptable.
You need to bump the idle up to 1100, and less timing. Big cams + low idle = surgey and poor idle
Last edited by letsgetthisdone; Aug 1, 2018 at 08:43 PM.