Spark plug fouling

[twobjshelbys]

Originally Posted by 169mph

I’m not replacing the EFI until I’ve ruled out all potential causes. When these issues originally started. I thought I could plug my laptop into the ECU and I would be able to run diagnostics to see if a sensor was faulty or a fuel injector was stuck open. Is this not possible. I’ve downloaded what I believe to be the latest FAST software for my ECU. I’m trying to find the correct USB to CAN connector so can I connect my computer to the ECU. Is this a waste of time? Again, I appreciate y’alls help. Thanks, Mike

So you've confirmed it's the FAST and not the Accel EFI system? If so that is good.

I would suspect you can get whatever tools you need to confirm the tune from them (FAST). If they have a standard tune that has evolved I'd say it probably won't hurt - treat it like any other software update. But if the tune was modified by Roush I wouldn't put a different tune in it. The reason is that the faux 8-stack injection is not linear with throttle position and air flow. I've gone into the details in other posts (don't ask me where) but the air flow over the throttle body vane varies by the position relative to the injector, with the net effect being that in the case of at least the Accel, at idle it was running extremely rich because the air/fuel didn't get a chance to mix until the throttle blade was open to about 1/2. I don't know how FAST deals with this characteristic. I never figured out who made the Roush 8-stack so if it is Borla you could perhaps turn to them for some advice on how the off the shelf FAST tunes work.