Only starts when throttle part open then runs super rich
Mean street unit with your new in tank pump 363cu Ford W Dart block aluminum heads big cam This is my first FiTech unit..Please Help
I put a mean street in with my big cam motor and got it working good. When I first installed it, I had a similar problem with the fitech reading normal AFR, but it running super rich and fouling my plugs. Turned out it was a leak at the O2 sensor. Once I got that sealed, it solved the problem. Big cam motors are especially sensitive to that, since there is way more overlap than moderate cams. The exhaust valve is open longer while the intake happens, resulting in drawing some exhaust in, and with a leak at the O2, fresh air in, throwing off the O2 reading. That's the first place I would look.
I'm Having the same problem. It will only start with pressing the pedal (open the butterflies). I installed the fitech with the older motor, I've recently rebuilt the motor and reinstalled the fitech. I measured the O2 sensor and it is 24 inches from the collection tube of the headman long tube headers, is that to far to get a collect a good o2 reading?
Have you tried reducing the Prime Fuel Multiplier under Cranking Fuel in the Pro Tuning section?
If you have to open the throttle to add extra air chances are the Prime Fuel squirt is too much. Default is 259. I lowered mine to around 110 and it starts great. I have the 600hp model and I am assuming the settings are similar.
I will try the prime fuel shot. does the O2 sensor need to be any closer to the collection part of the header?