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Re: MAF Return to idle
Posted: Mon Jun 05, 2023 7:24 pm
by Fast951
Tom wrote: Mon Jun 05, 2023 7:08 pm
My approach had two buttons used to calibrate the idle voltage -- one for a cold engine and one for a fully warmed up engine. When you push the buttons, it stores the pin 7 voltage, and the software extrapolates between cold and hot voltages as the motor warms up.
The temps can vary greatly, which may necessitate multiple cold calibrations.
To keep it simple, I wouldn't bother with a cold engine. No one should be boosting while the engine is cold!!!
The simplest solution is not to go to neutral once you lift, or blip the throttle while the RPMs are dropping.
The problem with manipulating the voltage is that it can hide some problems like a voltage drop between MAF and DME or a vacuum leak (if it occurs after initial calibration).
Years ago, when I supercharged my Expedition, I made an inline module to cap MAF voltage (basically what you are doing). It plugged between MAF and harness.
Obviously on the 951 the idle switch signal is also needed, so some wiring may be needed.
Re: MAF Return to idle
Posted: Mon Jun 05, 2023 7:55 pm
by Tom
Fast951 wrote: Mon Jun 05, 2023 7:24 pm
Tom wrote: Mon Jun 05, 2023 7:08 pm
My approach had two buttons used to calibrate the idle voltage -- one for a cold engine and one for a fully warmed up engine. When you push the buttons, it stores the pin 7 voltage, and the software extrapolates between cold and hot voltages as the motor warms up.
The temps can vary greatly, which may necessitate multiple cold calibrations.
To keep it simple, I wouldn't bother with a cold engine. No one should be boosting while the engine is cold!!!
The simplest solution is not to go to neutral once you lift, or blip the throttle while the RPMs are dropping.
The problem with manipulating the voltage is that it can hide some problems like a voltage drop between MAF and DME or a vacuum leak (if it occurs after initial calibration).
Years ago, when I supercharged my Expedition, I made an inline module to cap MAF voltage (basically what you are doing). It plugged between MAF and harness.
Obviously on the 951 the idle switch signal is also needed, so some wiring may be needed.
Agreed on boosting while cold.
I have to dig it out, but think I used the TPS pot rather than actual boost, so there were situations even cold where the unit would over-ride the MAF -- so needed the unit to provide an idle-friendly voltage from start-up to fully warm. Worked very well honestly.
Edit: and yes, mine would only intervene when the throttle switch is closed. It had a little multiplexer chip that passed the MAF signal through most of the time. The unit would constantly update the idle voltage and send it to the multiplexer, so that when the system needed to over-ride the voltage, it was just a matter of switching over to the replacement signal for a few seconds.
Re: MAF Return to idle
Posted: Tue Jun 20, 2023 3:00 pm
by MarkSzalaiy951
Hi all, i have a Huntley Racing MAF from around 1998 , also an Autoathority stage two chip and it goes right back to idle as long as i have no vacuum
leaks