Power FC Stock primary injectors need negative lag to idle at 14.7:1. ?Strange?
07-12-05, 11:06 PM
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Stock primary injectors need negative lag to idle at 14.7:1. ?Strange?
Hey guys...just bouncing this off you to make sure I'm not missing anything or doing anything idiotic.
Important airflow Mods:
PowerFC w/Datalogit (Duh)
RX7Fashion Intake
Bomex Intake pipe for rear turbo
Megan Racing DP & MP (no cats)
Racing Beat Dual tip
PLX M-300 Wideband
#9 plugs and new wires
I live at roughly 2800' altitude. I have O2 feedback turned off. My no-load and no-A/C idle was pushing 11.6-12.1:1 when I installed the PowerFC with the default map. After leaning out the affected idle cells until the AFR stopped changing (roughly 1.8's after a base recalc) I ended up at 11.8-12.3:1. It wouldn't lean out any further than that. I tried leaning out the 1000RPM field "Inj Adjust" under settings 3 and it had no effect. It's probably clamped just the same as the base map is. After doing some research on the board I started inputting progressively negative lag times into both primary injector lag fields on Settings 5. I ended up at -0.17 to come up with a 14.5-14.7:1 AFR at idle. After some light adjustments when I turn on the A/C it leans out for a second to roughly 14.9 then returns to 14.5-14.7:1. It idles like a champ and doesn't make your eyes water any longer.
So the question is...has anyone else needed that much negative lag time to get the car to idle at stoich with the stock primaries? I know alot of people don't idle modified rotaries at stoich so I may not be with a whole lot of company. I'm aware that the negative lag number should lean out the low end considerably then the effect should die off as load and pulsewidths increase. I'm going to tune the car out completely Saturday morning after I install the ASP Medium and alcohol injection this week. The other question I have is will the negative lag number cause any problems with me being able to fine tune the whole fuel map. I really doubt that but I figured I would check just to make sure.
Important airflow Mods:
PowerFC w/Datalogit (Duh)
RX7Fashion Intake
Bomex Intake pipe for rear turbo
Megan Racing DP & MP (no cats)
Racing Beat Dual tip
PLX M-300 Wideband
#9 plugs and new wires
I live at roughly 2800' altitude. I have O2 feedback turned off. My no-load and no-A/C idle was pushing 11.6-12.1:1 when I installed the PowerFC with the default map. After leaning out the affected idle cells until the AFR stopped changing (roughly 1.8's after a base recalc) I ended up at 11.8-12.3:1. It wouldn't lean out any further than that. I tried leaning out the 1000RPM field "Inj Adjust" under settings 3 and it had no effect. It's probably clamped just the same as the base map is. After doing some research on the board I started inputting progressively negative lag times into both primary injector lag fields on Settings 5. I ended up at -0.17 to come up with a 14.5-14.7:1 AFR at idle. After some light adjustments when I turn on the A/C it leans out for a second to roughly 14.9 then returns to 14.5-14.7:1. It idles like a champ and doesn't make your eyes water any longer.
So the question is...has anyone else needed that much negative lag time to get the car to idle at stoich with the stock primaries? I know alot of people don't idle modified rotaries at stoich so I may not be with a whole lot of company. I'm aware that the negative lag number should lean out the low end considerably then the effect should die off as load and pulsewidths increase. I'm going to tune the car out completely Saturday morning after I install the ASP Medium and alcohol injection this week. The other question I have is will the negative lag number cause any problems with me being able to fine tune the whole fuel map. I really doubt that but I figured I would check just to make sure.
Last edited by Trevor; 07-12-05 at 11:08 PM.
07-13-05, 08:57 AM
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Are the measured AFRs posted above from the M-300 readout or from the DATALOGIT log? Unless you have calibrated the DL to the M-300, the DL will read about .3AFR too lean.
07-13-05, 09:26 AM
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Both. They match...quality grounding hard at work.
It was a little lean in 800-1100 rpm range this morning when I cranked it up. Once it hit 75C+ coolant temps it was fine (back to right at stoich). It leaned out my cruise a little bit but it was previously a little bit rich...no biggie. Full throttle didn't change at all from what I can tell while keeping an eye on the wideband display. If I actually logged a pull I might see a small difference.
I'm going to have to increase the amount fuel when coolant temps are cold. Shouldn't take much to get it in there.
It was a little lean in 800-1100 rpm range this morning when I cranked it up. Once it hit 75C+ coolant temps it was fine (back to right at stoich). It leaned out my cruise a little bit but it was previously a little bit rich...no biggie. Full throttle didn't change at all from what I can tell while keeping an eye on the wideband display. If I actually logged a pull I might see a small difference.
I'm going to have to increase the amount fuel when coolant temps are cold. Shouldn't take much to get it in there.
Last edited by Trevor; 07-13-05 at 09:32 AM.
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