at what pressure does the computer put the car into "overboost" mode???

and what would the effects be?? maybe some hardcore fuel cut?

what I have experienced is once I hit 200-201 KPA it cuts my injectors from 80% to 60%... hmmm


HP Tuners | Garrett T3/T04B | 2.5" Charge Pipes | 2.5" Downpipe | 650 Injectors | HO Manifold | Addco front/rear | Motor Mounts | HKS SSQV | Spec stage 3 | AEM UEGO Wideband | Team Green LSD | FMIC | 2.3 cams | 2.3 oil pump swap | 280WHP | Now ECOTECED

Well, you're using the GMSC reflash w/ 2bar MAP, so I would guess anything over 2bar would be into "overboost", although I have no idea what the effect would be.


15.3 @ 89.97mph, 14's on the way?

I tried a 4.7 Volt zener diode in, and that cuts boost "computer values" at 155kpa, (which sounds like a 3.7-3.74 volt cut) but we searched the diode numbers and they all match up.. something is weird..



I also read that most 2.0 bar maps "over boost" around 4.74 volts or 13-14psi.


HP Tuners | Garrett T3/T04B | 2.5" Charge Pipes | 2.5" Downpipe | 650 Injectors | HO Manifold | Addco front/rear | Motor Mounts | HKS SSQV | Spec stage 3 | AEM UEGO Wideband | Team Green LSD | FMIC | 2.3 cams | 2.3 oil pump swap | 280WHP | Now ECOTECED

wtf sence would it make to cut fuel if there is to much boost? He thats a ton of air lets cut the fuel till it eiter blows up or goes down..... it would make alot more sence then it would cut spark even though thats bad for emessions (raw fuel innto exhaust) but its better then a blown up engine.

as far as I can tell, that is exactly what GM does for over boost.. @!#$ty deal i agree. spark would be a much better idea


HP Tuners | Garrett T3/T04B | 2.5" Charge Pipes | 2.5" Downpipe | 650 Injectors | HO Manifold | Addco front/rear | Motor Mounts | HKS SSQV | Spec stage 3 | AEM UEGO Wideband | Team Green LSD | FMIC | 2.3 cams | 2.3 oil pump swap | 280WHP | Now ECOTECED

actualy most manufacturors use fuel cut for overboost protection. it doesnt lean it out, it shuts the injectors right off. no fuel=no combustion, so essentialy the motor is shut off untill it comes under a certian rpm and map value.

spark cut is not ideal. first off raw fuel in the exaust will kill a cataletic converter in no time flat. along with that, backfiring becomes an issue, and as cool as it may be to shoot some flames, it can actualy be very dangerous not just for people behind it, but if you get some raw fuel built up in the muffler or cat and it lights.

then why wouldn't GM cut all the fuel, instead of 20% or so... see pic



injector duty cycle is at the top, map is purple on #2


HP Tuners | Garrett T3/T04B | 2.5" Charge Pipes | 2.5" Downpipe | 650 Injectors | HO Manifold | Addco front/rear | Motor Mounts | HKS SSQV | Spec stage 3 | AEM UEGO Wideband | Team Green LSD | FMIC | 2.3 cams | 2.3 oil pump swap | 280WHP | Now ECOTECED

You could do a "fake 3 bar" and rescale everything and wire in a 3bar map sensor, you wouldnt lose much resolution going from a 2bar to 3 bar and its driveability would be pretty good still

other solutions megasquirt, or somehow limiting the voltage to a certain level on the map sensor output, not sure how to do that



1989 Turbo Trans Am #82, 2007 Cobalt SS G85

I tried a 4.7 volt zener diode, but it had cut around 4ish volts (155kpa) and we checked all the numbers it is a 4.7volt.. so that sucked...

when I get back in 2 weeks I am pulling the turbine housing off and making sure that I do have a 0.63 housing (believe the housing is 0.48) and also porting the gate about 20-30% larger.



HP Tuners | Garrett T3/T04B | 2.5" Charge Pipes | 2.5" Downpipe | 650 Injectors | HO Manifold | Addco front/rear | Motor Mounts | HKS SSQV | Spec stage 3 | AEM UEGO Wideband | Team Green LSD | FMIC | 2.3 cams | 2.3 oil pump swap | 280WHP | Now ECOTECED

weird...... back in the day I ran upwards of 18psi and didnt get any fuel cut issues. I was running the GM 2bar MAP and S/C reflash as well....... granted I didnt have anything to log it with, but I never 'felt it' either.






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