Stang 427 Imo i find that most cars that run under 10 ins..Let me be clear here will it work . YES. But will it work as advertised i say no. The O 2 only sees average you dont have a O2 on every cyd.. the thing i see is basically it is a electric carb..That is really the reason a dual plain manifold does not work very well at low speed because the long short runner deal.. It just dumping fuel some rich some lean causing the o2 goes crazy. Now throw in a 250 cam at 50 now the reversion starts most of the time i find it to be at 2000-2500 that is biggest problem area. Most of the time that is were most cars run around on the street. If all i had to worry about is idle and WOT it would be a piece of cake. Hey the other thing is how picky you are.When you do this for a living they have to be in 95-99% perfect.. So will it work yes..Will you have driveibilty issues yes!! IMO
.
Well I am not sure I know too many people that tune as fussy as I do, but I am glad there are others. Additionally, I'd add that if you are trying to really do something serious, go port injection, that way you can time injection based on valve events and really clean up idle, even with a big cam. Sometimes that means spraying the backside of a closed/hot valve, but usually it's a combination of PW/PD and timing.
The big thing is, I am
not disagreeing with you, but I am saying that what you are seeing is not due to low vacuum. It's due to the overlap, you just happen to see low vacuum when the cam is rowdy. The challenge of tuning due to a big cam is not from fuel falling out of suspension, it's not poor cylinder fill, it's the O2 sensor seeing raw fuel mix that came through when both valves were open, and although a cam with a lot of overlap will
cause low vacuum, it's the overlap that gives the EFI fits. Additionally, if the engine pushes back that much reversion, that's a cam and port design problem more than an EFI problem and better to fix the real issue
In the end though, do what you have had success with. I think we are saying the same thing...if you want to do it right for a big cam, you need to be able to get into the system to program it.
I have had great luck with big street cams and EFI, and those that get real big cams and slow ports, can still run well, but you need to look at open loop tuning when you can't get the system to react the way you want. I don't like open loop tuning, and I do all I can to not do that, but if done right it works great and you can't even feel the transition to closed loop
FWIW, I have done a few Powerjections too, crappy cheap system and not very intuitive, but they are fully laptop programmable and can log right out of the box. I don't recommend the system because they don't seem to be too well made and have very little real support, but they are very adjustable. My own car is a MAF SEFI system based off a Massflo/A9L Ford system, but has a Quarterhorse chip that allows me to log both dual NB O2s and a wideband O2 as well as any other parameter in the ECM and really dig into any parameter I want. I like the system, but you need to run a MAF and they can be a bit of a pain for packaging on an early car.
I haven't decided if I will try the FiTECH on my 445 F100, but if I do, even with a lot of vacuum, I think I would prefer the programmable version over the plug and play handheld.
