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Discussion Starter · #1 ·
Well I dynoed my RL on Saturday with good results (http://www.cobaltss.com/forums/showthread.php?t=1906) but I did run into one problem. On the first run there was slight detonation in the lower RPMs (lower being around 2400). We are not 100% sure but we think it was caused by the larger increase in boost. The computer tried running the stock map but with the increase in boost it wasnt able to which we believe caused the problem. Once the CPU reliezed it couldnt run the map it compencated and problem solved for the other 2 runs. How ever, the car will try the stock map first before compansating. Im running a 3" pulley @ 15psi. I swapped it out for for a 3.25" yesterday and that should fix it. Moral of this story is, anything above 14 psi, some kind of engine managment or reflash is needed. Just a heads up...

Also, my injectors are wide open by 5500 rpms which is around when I hit 15 psi. Bigger injectors would have helped alot. Dispite that, the car never leanned out. I forget my exact ratio but I'll check the print out and post it up later.
 

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you should ALWAYS reset the ecu right after any mods. what kind of stuff do you use to measure injector load, i hear about it but have never actually seen anyone do it
 

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Discussion Starter · #5 ·
My A/F ration never dipped below 12:1 so it wasnt that. The only way to remap or tune the cpu is with either psi-fi piggyback or waitin for the stage upgrades. I think Im going try and get just the injectors and reflah from the stage upgrades and use my own pulley, if they will let me.
 

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So just how did you calculate your injector duty cycle, to indicate they were "maxed out" ? (Numbers please)
AND
what makes you think you had detonation at 2300 rpm?
WOT
 

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WopOnTour said:
So just how did you calculate your injector duty cycle, to indicate they were "maxed out" ? (Numbers please)
AND
what makes you think you had detonation at 2300 rpm?
WOT


that's what i'm waiting on. don't you have to have some crazy ass computer setup to measure injector load? i thought those systems were f'n expensive
 

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Discussion Starter · #8 ·
When dynoing my car the tech pulled up a graph showing my fuel preasure leveling out @ 5500 rpm. As I was thinking about this last night I had an idea. Is it possible that its leveling out do to the fact nothing was remaped or could it be the injectors maxing out? As for how that info was calculated, I have no idea... Same with the detination. The tech was reading info off the computer and said it looked like there was some detination down low on the first run and that the car compinsated on the other two and the detination was gone.

Im by no means an experet. Im just passing on info that was passed to me. On this situation, I hope someone can prove me wrong.
 

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GM3saturn said:
When dynoing my car the tech pulled up a graph showing my fuel preasure leveling out @ 5500 rpm. As I was thinking about this last night I had an idea. Is it possible that its leveling out do to the fact nothing was remaped or could it be the injectors maxing out? As for how that info was calculated, I have no idea... Same with the detination. The tech was reading info off the computer and said it looked like there was some detination down low on the first run and that the car compinsated on the other two and the detination was gone.

Im by no means an experet. Im just passing on info that was passed to me. On this situation, I hope someone can prove me wrong.
the fuel pressure probably leveled out because the boost probably leveled out or maybe even started to drop a little

im sure an obd2 scanner would show you IDC's

any idea what size injectors you guys have on your cars?
 

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Antyoo said:
the fuel pressure probably leveled out because the boost probably leveled out or maybe even started to drop a little
These cars use a "returnless" fuel system so the fuel pressure regulator is not compensated for varying intake pressures mechanically (ie via a compensator port connected to the intake manifold via vacuum line ) The basic spec if 55psi AT ALL TIMES but often is closer to 60psi except for at maximum load, where it does drop slightly.

Antyoo said:
im sure an obd2 scanner would show you IDC's
General Motors ECM/PCMs do NOT output a PID for IDC. It always will need to be calculated in the standard fashion using base pulse width and RPM.GM will often drive high impendance saturated switch type injectors (such as the LSJ) all the way to 100% Duty Cycle in power enrichment modes.
GM3saturn said:
On the first run there was slight detonation in the lower RPMs (lower being around 2400). We are not 100% sure but we think it was caused by the larger increase in boost.
I would be real surprized if you/they detected knock at 2400 rpm, there's would be hardly any boost or heat to create it (unless something was seriously wrong) What was being used to detect the knock? KR on a scan tool? scope on the factory KS? Secondary KS to the dyno??

HTH
WopOnTour
 
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