FAST Engine EFI Needing help

[TumbleweedCobra]

I have an old Speed pro, now known as a FAST ECU. I’m not getting the injectors to fire on half the engine. The other half is working great. All of the injectors have power but the non working side doesn’t have the ground connection occurring. engine starts and runs well, considering the right side is all that is running. Any thoughts on what might be the issue? All sensor inputs are common for the full engine.

[bobl]

The ecu provides a ground to fire the injectors. If you look at the ecu pinouts using the ccomp software help menu you can see how it's wired. 4 injectors are on one connector and 4 on the other. There are also multiple ground pins. The system is most likely set up for batch fire which means it fires 4 injectors at a time. So you would need to verify all your system parameters for something obvious like number of cylinders defined. Then it could be a connector problem on the ecu itself or quite possibly one of the grounds is broken or not connected. Then there is always the possibility of a hardware failure with the injector drivers. Just a few thoughts that come to mind. It's been many years since I worked on one of these FAST grey boxes. I assume the Speedpro preceded that and still used the same software.

Bob

[TumbleweedCobra]

The ecu provides a ground to fire the injectors. If you look at the ecu pinouts using the ccomp software help menu you can see how it's wired. 4 injectors are on one connector and 4 on the other. There are also multiple ground pins. The system is most likely set up for batch fire which means it fires 4 injectors at a time. So you would need to verify all your system parameters for something obvious like number of cylinders defined. Then it could be a connector problem on the ecu itself or quite possibly one of the grounds is broken or not connected. Then there is always the possibility of a hardware failure with the injector drivers. Just a few thoughts that come to mind. It's been many years since I worked on one of these FAST grey boxes. I assume the Speedpro preceded that and still used the same software.

Bob

Bob, Thank you for the reply and great ideas!, the software was set for 8 cylinders, will take a closer look at the wiring and pins. It was working well before I pulled the engine and the harnesses. Wondering if something came loose in the process.

[33fromSD]

Bob, Thank you for the reply and great ideas!, the software was set for 8 cylinders, will take a closer look at the wiring and pins. It was working well before I pulled the engine and the harnesses. Wondering if something came loose in the process.

Recheck the SW too, not the same system I realize, but on my Holley Sniper EFI in my 70 Challenger last year I was having EMI issues (I mistakenly crossed the harness from the coil over the 12V line) that was actually causing confusion to the ECU to the point it reset it self constantly changing the setting from 8 cyl back to 4. Once Holley and I figure out what was going on, life has been good ever since.

[33wanabe]

I have a fast, street version, and i have 5000 mi. still trying to keep it in tune. not happy at all !