Injector ECM calibration
10-27-2002, 05:54 PM
#1
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Injector ECM calibration
Hi.
(My car is a Corvette 1990 L98 man 6-shifted ORIGINAL this far)
Could any of you pro's help me out calibrating my new
Injector flow rate constant.
As it is right now i'am using the original injectors.
Tunercat says my flow-rate is 22.1
Now i'am about to replace those with FORD SVO 24#, but still
use my original fuel-pressure.
So how and what should the new value of the Injector flow rate be?
(Yes i know, there is a FAQ, but i really wanna be sure one this one)
(My car is a Corvette 1990 L98 man 6-shifted ORIGINAL this far)
Could any of you pro's help me out calibrating my new
Injector flow rate constant.
As it is right now i'am using the original injectors.
Tunercat says my flow-rate is 22.1
Now i'am about to replace those with FORD SVO 24#, but still
use my original fuel-pressure.
So how and what should the new value of the Injector flow rate be?
(Yes i know, there is a FAQ, but i really wanna be sure one this one)
10-29-2002, 11:21 AM
#4
Re: Injector ECM calibration (dahlman)
What is stock pressure for the L98?
I've been told this formula
Effective Injector Size = (Square Root of (Your Fuel Pressure / Rated Fuel Pressure)) * Rated Injector Size
It's about as good a formula as any I suppose, Ford Injectors are rated at 39 pounds, so if your L98 runs 46 PSI like the LT1 does then you can use the formula and figure out that they are effectively 26.1's. If that formula is accurate it should run exactly as it did before you changed them and all of your fuel economy calculations will still be correct.
I know that with my 24's the computer was a little optamistic on it's calculations. It was close but it was still about 1-2 mpg better than it was really getting. This makes sense if you figure that it had to cut the pulse width down so it thought it was running a smaller injector than it really had for a shorter period of time. In this case it thought it was adding a good deal less fuel.
I've changed the injector constant on mine from the stock 23.8 to 26.1 and so far so good. I did this in the middle of a tank of gas though and didn't reset my averages and such. As soon as I fill up again and reset that I'll see if the fuel economy is more accurate. I really felt like I needed to change it because currently my car's 02 sensors are worthless. They don't get hot enough to send accurate signals back to the computer and therefore the computer can't adjust properly. I thought it would be best for it to be programmed for the proper injector size while it was in open loop because it can't accurately adjust anything in closed loop.
I've been told this formula
Effective Injector Size = (Square Root of (Your Fuel Pressure / Rated Fuel Pressure)) * Rated Injector Size
It's about as good a formula as any I suppose, Ford Injectors are rated at 39 pounds, so if your L98 runs 46 PSI like the LT1 does then you can use the formula and figure out that they are effectively 26.1's. If that formula is accurate it should run exactly as it did before you changed them and all of your fuel economy calculations will still be correct.
I know that with my 24's the computer was a little optamistic on it's calculations. It was close but it was still about 1-2 mpg better than it was really getting. This makes sense if you figure that it had to cut the pulse width down so it thought it was running a smaller injector than it really had for a shorter period of time. In this case it thought it was adding a good deal less fuel.
I've changed the injector constant on mine from the stock 23.8 to 26.1 and so far so good. I did this in the middle of a tank of gas though and didn't reset my averages and such. As soon as I fill up again and reset that I'll see if the fuel economy is more accurate. I really felt like I needed to change it because currently my car's 02 sensors are worthless. They don't get hot enough to send accurate signals back to the computer and therefore the computer can't adjust properly. I thought it would be best for it to be programmed for the proper injector size while it was in open loop because it can't accurately adjust anything in closed loop.