E8 BAC settings
 

Anybody has any recommended settings?

What is the pullups settings? Nothing in the manual.
BAC frequency?

Thanks,
Ian

What valve are you going to use? stock 2 wire mazda? email Haltech, im sure they can give you some ball park settings.

Yup stock mazda BAC.

Thanks for the reply. I will call haltech.

Ian

I use 250 as the BAC freq, certain freq will make the bac squeek

For the FD BAC.

BAC Freq................ 275
Prop Co Eff............. 550
Int Co Eff................ 20
Der Co Eff............... 0

Here's Haltech's instructions for the BAC setup.

BAC Valve Idle Control
Brief Description
BAC valve idle control is used to hold steady the RPM when off the throttle. This
method of controlling RPM at idle is done by looking at the difference between the target
idle RPM and the current RPM and adjusting the BAC valve’s output duty cycle until the
difference is zero.
Settings
· BAC Frequency Frequency that the BAC will run at.
· Temp Threshold Below this value the engine is considered cold,
above this value the engine is considered warm.
(E.g. 65 - 70°C).
· Cold Target RPM The target RPM at which the Engine will idle
when below the ‘Temp Threshold’.
· Cold Start Duty This is the duty cycle that the BAC valve will
default to when the engine RPM is falling
towards the ‘Cold Target RPM’, before it
begins its idle control and when coolant temp is
below the ‘Temp Threshold’. This value
should cause the engine to idle at a speed just
above the ‘Cold Target RPM’. If this value is
too low then the RPM will fall below the ‘Cold
Target RPM’.
· Cold Min Duty The minimum duty cycle the BAC valve will
reach when controlling the idle and when the
engine is considered cold. Set so that the engine
won’t stall. This acts like a throttle stop.
· Warm Target RPM The target RPM at which the Engine will idle
when above the ‘Temp Threshold’.
· Warm Start Duty This is the duty cycle that the BAC valve will
default to when the engine RPM is falling
towards the ‘Warm Target RPM’, before it
begins its idle control and when coolant temp is
above the ‘Temp Threshold’. This value
should cause the engine to idle at a speed just
above the ‘Warm Target RPM’. If this value is
too low then the RPM will fall below the
‘Warm Target RPM’.
· Warm Min Duty The minimum duty cycle the BAC valve will
reach when controlling the idle and when the
engine is considered warm. Set so that the
engine won’t stall. This acts like a throttle stop.
· Post Start Offset Duty On start up, this opens up the BAC valve to help
start the engine by allowing more air. This value
is added on to the ‘Cold Start Duty’ when the
engine is cold or to the ‘Warm Start Duty’
when the engine is warm. This new calculated
value is used when the ECU is initialized and
the engine is not running and also for the first
three seconds of the engine running.
· RPM Dead Band Used to stop the idle controller from ‘over
controlling’ the idle due to the small
fluctuations in RPM when idling. E.g. target
RPM = 1000RPM, dead band = 50RPM,
therefore if the engine RPM fall between
950RPM and 1050RPM then the idle controller
will ignore any changes in RPM and considered
it to be controlled. (E.g. 15 – 50 RPM).
· Decel RPM Rate This value helps determine if the RPM is falling
or steady when off the throttle. When the RPM
is steady then it is ready to be controlled. If this
value is set too low then the fluctuations of an
RPM which is hovering consistently around one
point will make the controller think that the
RPM is never steady. If this is set too high then
the RPM could be considered steady when it is
still falling. (E.g. 25 – 50 RPM).
· Decel to Idle Control Wait When the RPM has finished falling and has
become steady, idle control will happen after
this period of time.
· A/C Duty Increase This value is added to the ‘Cold Start Duty'
when the engine is cold or to the ‘Warm Start
Duty’ when the engine is warm. It is done to
handle the extra load when the air con is turned
on. It is taken away again when the air con is
turned off.
· A/C RPM Increase This value is added to the ‘Cold Target RPM’
when the engine is cold or to the ‘Warm
Target RPM’ the engine is warm. It is done to
handle the extra load when the air con is turned
on. It is taken away again when the air con is
turned off.
Typical Values
· BAC Frequency 500
· Temp Threshold 70°C
· Cold Target RPM 1200 RPM
· Cold Start Duty 70
· Cold Min Duty 1
· Warm Target RPM 800 RPM
· Warm Start Duty 50
· Warm Min Duty 1
· Post Start Duty Offset 25
· RPM Dead Band 25
· Decel RPM Rate 25
· Decel to Idle Control Wait 2
· Air Con RPM Increment 100
· Air Con Steps Increment 10
Setup of BAC Valve Idle Control
The following steps will guide you through a method to setup and tune your idle
control.
1. Ensure that your Fuel and Ignition maps are well tuned and warm your engine up to
operating temperature.
2. Make sure that your throttle is properly calibrated so that throttle position in the
engine data reads zero percent when you are completely off throttle.
3. Check all the settings of the idle controller, the above values are a good place to
start.
4. The engine should idle around the ‘Warm Target RPM’, adjust this value to
change at what RPM the engine will idle when warm
5. Adjust the ‘Warm Start Duty’ so it is about 5 – 10% above where the BAC valve
is sitting when the idle is controlled.
6. Adjust the ‘Warm Min Duty’ so it is about 5% below where the BAC valve is
sitting when the idle is controlled.
7. Steps 4 – 6 will need to be repeated for when the engine is cold.
Tuning Advance Sensitivity
Starting Point for PID values
· Proportional Co-efficient 50%
· Integral Co-efficient 50%
· Derivative Co-efficient 0%
Tuning the PID Values
1. Set all Proportional, Integral and Derivative to zero
2. Bring up the Proportional in increments of 5% until you see a small oscillation in
the RPM. Note: the RPM will not reach the target RPM with only the Proportional
part of the controller being used.
3. Bring up the Integral in increments of 5% until you cancel out the oscillation in the
RPM. When the Integral part is introduced the RPM will go to the target.
4. The Derivative term should remain at zero.
Notes
· If the idle speed fluctuates or oscillates, reduce the idle sensitivity parameters
slowly until the oscillation stops. If the idle speed is slow to reach the target,
increase the idle sensitivity parameters slowly until it begins to oscillate and then
reduce the values slightly.
Idle Troubleshooting
· When the engine is started check that the idle speed begins high and falls back to a
stable idle speed around the target. Increase the ‘Post Start Duty Offset’ if
required to aid in starting.

I tried these settings:
BAC Freq................ 275
Prop Co Eff............. 550
Int Co Eff................ 20
Der Co Eff............... 0

I have an FD BAC and intake system, and get much better idle controll with the freq at 225. With 275 there is also a noticable intake noise from the BAC that is gone at 225.

Thanks guys for the info.

I called haltech and they suggested 33 as the freq. (May very well be different since its an FC?)

Thanks again.

Ian

33 sounds like the freq they suggest for boost control solenoids

I told the dude for the BAC valve. Stock coil. So hopefully we were not mistaken. I will try both. :)

Ian for what it's worth, my Boost Solenoid said it was 33.

I tried 33 and it makes lots of noise at that setting.