ECUflash Adjusting BISS Screw with Evoscan

[ZombieSix]

This is how to adjust your BISS using Evoscan, This is how i have figured out how to do it since we do not have ISCPosition or LearnedIdleAdjust in evoscan. You will need to adjust your biss if your idle is fluctuating or your car wants to die on you when you come to a stop.


From the VFAQ

If you've added any mods to your car that increase airflow through the engine (especially IC pipes or a frontmount IC), you may have a problem with the car stalling, or the idle oscillating up and down when coming to a stop. One of the most common causes is the BISS screw being out of adjustment. Another reason to change the BISS setting is if you have moved to a higher or lower elevation and you are experiencing the above symptoms.

The BISS helps the ECU maintain idle. The ECU uses the Idle Speed Control (ISC) stepper motor to hold the idle speed as constant as possible. The ECU counts on the ISC being in the center of its operating range to have as much control over the idle as possible. While the BISS may have worked fine on a stock car, as soon as you start increasing airflow, you can push the system to the point where the BISS is not bypassing the proper amount of air past the throttle, so the ECU has to push the ISC stepper motor past the halfway point to maintain proper idle speed. Stalling happens if the BISS is set wrong, the ECU pushes the ISC to full lock, and can't push it any farther, and full lock of the ISC is not giving enough airflow to keep the engine running.

The following conditions should be met before setting the BISS:

Engine coolant temp 176-203 degrees F (engine fully warmed up with the temp needle in the center of the range)
Lights, cooling fan, and accessories OFF
Tranny in neutral (AT trannies in Park)
Steering wheel in neutral position (centered, no load on the power steering)


Here we go
1. Once your car meets the following criteria hook up your Openport 2.0 cable and open Evoscan
2. In evoscan in the bottom right corner where it says actuators click that button.
3. A little menu pops up of different things to activate, you can not activate something while you are logging. Click the bottom one Speed Adj. Screw Mode
4. Your cars idle will probably fall and she might even die, this is normal, (if she dies you need to loosen the biss screw a bit and try this step again) Now you go to your throttle body and begin turning the BISS screw tighten to lower RPM and Loosen to increase rpm (your prlly here to loosen it) When she sounds like shes idling right (about 850 +/- 50) You need to go into the car and DEACTIVATE the Speed Adj. Screw Mode
5. Your RPM will go up to about 1500 or so, This is normal, You need to then turn evoscan on and begin logging watching the RPM drop. After about 8 minutes the actual RPM should match the TARGET RPM, if it does not you need to adjust the biss some more. Go back to step 2. If it does then you are done, congratz give yourself a pat on the back and enjoy your car not dieing when you come to a stoplight.

 

[Tony818]

Hey thanks for the write it's pretty straight forward. However it seems as my evo scan isnt engaging even tho I hear the computer say "link engaged" heres a pic

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