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-   -   boost cuts spark at 10ish PSI. what ways are there around this hinderance? (https://www.mazda3club.com/3rd-gen-protege-mazdaspeed-p5-mp3-26/boost-cuts-spark-10ish-psi-what-ways-there-around-hinderance-36802/)

DonSVO October-6th-2004 10:57 PM

boost cuts spark at 10ish PSI. what ways are there around this hinderance?
 
my boss and i were talking about this over lunch. we would like to make a sort of 'voltage limiter' to affect the VREF signal sent to the PCM from the MAF. this would either limit or disrupt the increase in voltage the PCM would see as the MAF signaled that more than "suitable" air quantities were going into the motor, I.E. more than 10 PSI.

is there a way to create this? my thinking says to wire in a separate jumper wire to the VREF signal wire. this would just splice into the wire, and it would only activate once 9 PSI of boost is seen (meaning you are well on your way to a +10 PSI WOT situation). my idea includes a voltage limiting set of resistors set to turn on via a Hobbes switch, keeping the VREF from being affected during normal driving.

the MSP runs rich as a dog anyways, this would be tested on a dyno while monitoring the A/F ratio with a wideband. a PSI at a time, all the while pretty much sending the PCM a signal saying i am still just at 10 PSI. i assume, judging from the ratios in all of my 9.5 PSI dyno runs, that i could safely squeeze 13-14 PSI on pump gas without exceeding 12.5:1.

does anyone have input? are there flaws in my thinking???

Roddimus Prime October-7th-2004 08:56 AM

you didn't listen to anything when I was explaining this to you earlier.....it's not based on boost dude...it's MAF voltage limits. You could hit the spark cut at 4psi or 40psi....Once the MAF voltage reaches peak it cut sparks....It's based on air volume not pressure.

Look up "JoeP FCD" he already has this problem solved.

Good luck not popping your motor.


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