Originally posted by bruce
No injector has a lean spot.
Like I said, they have different characteristics, and to do the proper calibration for one, means redoing the MAF Tables.
The only correct way to match an injector to an MAF system is to go thru and map out the MAF Tables and scalars.
FWIW, I have 6 injectors of one size, and a 7th that's a different size, and tuning the MAF tables and scalars has the engine running just fine.
Ok, ok, ok, now wait, I dont USE a MAF, and I had to add a LOT of fuel just off idle in my FAST. I got privvy info from a certain vendor whom I was tight with and MSD/Delphi 50's are proportionately LEANER than stock at 6 and 7mS, so while you can make up for this in your MAF table (which is incidentally exactly what I do) there isnt any denying if an injector flows X fuel at 4 and 5 mS and not incremetally MORE at 6 and 7mS for example, then that is very much a lean spot. I think this is the reason Lance doesnt like Rochester injectors (which were the original Delphi's). His reasoning if I remember right, was harmonic ringing in the magnet assy made it an unreliable, or maybe unpredictable injector. And is why he and FAST sell Bosch injectors. He says theyre the best.
Furthermore, if you've never witnessed the Delphi cold stall/rolling idle then maybe you've been lucky. My fix was different than yours for one reason...I like taking few steps to reach a goal, not a million steps to reach the same goal, driveability. I think I had my car running as good as it would get. I dont need open loop. My car idled fine, transitioned fine, yes, had a SLIGHT gag on 1 out of 20 pedal snaps to 1/2 throttle which I could have fixed in the TPS delta, but it didnt do it consistantly enough for me to care. Call me dumb, lazy, whatever, thats fine. Its easier to back yourself out of a problem in 2 steps, than 100.
So if you want to say you haveta tune your MAF table, thats fine, but in a perfect world, a 1,2,3,4,5mS an injector should flow A,B,C,D,and E# of fuel not A,B,B,B,D,D# worth of fuel. That is very MUCH an injector thats has a different characteristic. Hell, if injectors didnt act differently, we wouldnt NEED to fool with MAF tables and scalers now would we? One MAF table would fit all wouldnt it? It would seem, by modding MAF tables to achieve a certain driveability, would mean youre pulsing that injector say 7.5mS vs 7mS that another injector might need at the same RPM range (Or even maybe 5mS in the case of 009's). You call it characteristic, I call it lean. If you had to add fuel to richen up a RPM/Load range, to ME it was LEAN. If I gotta pull fuel, to ME its RICH.
I'll fire up my laptop tomorrow and capture my VE table screen and show you I had to make a MAJOR jump in the values to overcome a lean sag just off idle which I DIDNT have with the 50's. If the injectors ARENT different, then what caused this when NOTHING else changed in my car?
