SCT tuning help

[rubydist]

My first step toward a turbo install will be getting 48lb injectors and a Lightning 90 mafs and install them on the currently n/a setup to get the base tuning dialed in. (I already have SCT ProRacer, CHIPper, chip, etc. and have done SCT tuning previously.)

My question is this: you guys who have tuned for 48lb Accel injector and/or Lightning 90 mafs via SCT - do the data files the SCT provides work acceptably as a starting point, or do they need rework? What else besides injector slopes, offset, mafs transfer functions and cranking p/w need to be changed as a starting point?

Does injector timing need changed? p/w vs. voltage? Anything else?

I'm just trying to reduce the "reinventing the wheel" syndrome as much as possible.

tia

 

[yamahaSHO]

Start with the OEM curve for that particular MAF. As far as the injectors, this may help. http://www.shoforum.com/showpost.php?p=1303564&postcount=2

Do not mess with injector timing.

Assuming the MAF curve is correct (which is why you start with a known curve), you'll need to scale the injectors via HS/LS/BP, injector offset (latency), and scale the starting tables based on old size of the new injectors (old injector/new injector and then multiply that to the starting tables).

 

[rubydist]

yes, I read that thread - thanks.

unfortunately, the numbers are different between the Tweecer and the SCT, so I really need feedback from the SCT gurus.

please explain how injector timing is different from injector latency.

 

[Mr Anonymous]

yes, I read that thread - thanks.

unfortunately, the numbers are different between the Tweecer and the SCT, so I really need feedback from the SCT gurus.

please explain how injector timing is different from injector latency.

The number's aren't really "different" between SCT and TwEECer, they're just presented differently so you have to do some math to convert kg/hr to lb/min, or convert a/f to lambda, etc.

 

[rubydist]

ok, thanks. I figured out the difference in units for slope, and the base numbers in the SCT table for Accel 48s are almost the same as the Tweecer numbers that Jason presented.

1. what are the units on the injector breakpoint? (the SCT value is .0000246)

2. when cranking, does the commanded pulsewidth (crank_fuel_pulsewidth) get multiplied by the values in the fuel injector battery compensation table (injector_comp_battery)? because the way SCT presents that - it is not multiplied by the battery compensation table, but Jason's suggested numbers are the same as stock, which indicates that it is. anyone have clarity on this point?

3. does anyone have experience with the transfer function for the Lightning 90 mafs?

 

[yamahaSHO]

please explain how injector timing is different from injector latency.

Timing is... Timing. Injector Offset vs Battery Voltage (or Latency) is a pulsewidth adder. Injectors behave differently at different voltages. The lower the voltage, the slower it will open so you will need an adder to compensate in order to hit targets. Higher voltage require less adder obviously.

Injector Offset adder mostly affects idle and cruise, but makes up a very minor amount of fuel at higher pulswidths. This is also key in getting the car to run well with and withou AC running, as well as any other major power draw.

2. when cranking, does the commanded pulsewidth (crank_fuel_pulsewidth) get multiplied by the values in the fuel injector battery compensation table (injector_comp_battery)? because the way SCT presents that - it is not multiplied by the battery compensation table, but Jason's suggested numbers are the same as stock, which indicates that it is. anyone have clarity on this point?

Doesn't really matter. You manipulate the whole table until it starts.

3. does anyone have experience with the transfer function for the Lightning 90 mafs?

What experience are you looking for? The OEM curve is out there.

 

[rubydist]

ok, got it. thanks.