Rotary Car Club - View Single Post - Installed new injectors, now it won't stay running

scotty305 · 12-12-2010, 01:47 AM

If you had an FJO peak/hold injector driver, that means you will probably need to increase the injector offsets for the new injectors. It's my understanding that most peak/hold injectors will snap open more quickly (when using a peak/hold driver) than high-impedance injectors. If you haven't accounted for this, you'll probably need to increase the fuel map even more (although the correct thing IMHO would be to increase the injector offset values instead). Again, there may be some PFC-specific tricks or hoops you need to jump through here.

I have an AEM EMS. I've done quite a bit of tinkering with my car's fuel map, and found that the engine will still idle (albeit poorly) when the mixture is pretty rich (9's-11's AFRs) but does tend to stall pretty easily if too lean (14-15 AFR will stall more easily than 10-11 AFR). Something else that has worked for me is to flatten out the fuel map near idle (same exact pulsewidth from about 500-1500RPM, 0-50kPa), change all cells equally to get things roughed-in, then eventually make small adjustments to each cell to ensure the AFR doesn't go lean when turning on the fans / headlights or when slowly letting out the clutch to creep forward.

12-12-2010, 01:47 AM	#4
scotty305 Rotary Fan in Training Join Date: Mar 2008 Location: Culver City, CA Posts: 84 Rep Power: 18	If you had an FJO peak/hold injector driver, that means you will probably need to increase the injector offsets for the new injectors. It's my understanding that most peak/hold injectors will snap open more quickly (when using a peak/hold driver) than high-impedance injectors. If you haven't accounted for this, you'll probably need to increase the fuel map even more (although the correct thing IMHO would be to increase the injector offset values instead). Again, there may be some PFC-specific tricks or hoops you need to jump through here. I have an AEM EMS. I've done quite a bit of tinkering with my car's fuel map, and found that the engine will still idle (albeit poorly) when the mixture is pretty rich (9's-11's AFRs) but does tend to stall pretty easily if too lean (14-15 AFR will stall more easily than 10-11 AFR). Something else that has worked for me is to flatten out the fuel map near idle (same exact pulsewidth from about 500-1500RPM, 0-50kPa), change all cells equally to get things roughed-in, then eventually make small adjustments to each cell to ensure the AFR doesn't go lean when turning on the fans / headlights or when slowly letting out the clutch to creep forward.