I just went from 36lb to 42lb injectors, now at idle its all over the place. sometimes it just dies. I changed my injector con to 0.11571, by using shifted formula, then I found another by skwirl and I put it at 0.10171. Now the car runs worse. Also for some reason the afr error isn't coming out right. I was going to try using this formula [actual afr- commanded afr / commanded afr * 100]. does this look right?

Best to use your stock injector constant.

so [stock constant]*([stock injector size]/[new injector size]) = [new constant].

Also remember that your fuel pressure is different than the fuel pressure of the injectors so you will need to convert the flow of the injectors at the given pressure to your pressure at 0 vac (basically the pressure of the fuel with the key to the on position but the car not on).


1994 Saturn SL2 Home Coming Edition: backup car
2002 Chevy Cavalier LS Sport Coupe: In a Junk Yard
1995 Mazda Miata R-package Class=STR
Sponsored by: Kronos Performance

WPI Class of '12 Mechanical Engineering
WPI SAE Risk and Sustainability Management Officer

It was set right the first time, the injectors didnt fit right. They were older ford green tops, but it let air into the fuel rail causing my idle issue. I just put the old ones back in and it runs great

well that was easy.


1994 Saturn SL2 Home Coming Edition: backup car
2002 Chevy Cavalier LS Sport Coupe: In a Junk Yard
1995 Mazda Miata R-package Class=STR
Sponsored by: Kronos Performance

WPI Class of '12 Mechanical Engineering
WPI SAE Risk and Sustainability Management Officer

Leafy.....

Im going to be doing some data logging of my current setup soon. I will be adding LSJ (instead of brown tops) to my boosted LD9. I was looking for the forumla. So its

[stock constant]* the value of ([stock injector size]/[new injector size]) = [new constant]. It should work fine on my setup?


GMR has got nothing on this

That's mostly correct, unless the fuel pressure on your is different than the lsj. Then theres a flow rate calculator in one of the menus of hptuners that will do it for you.


1994 Saturn SL2 Home Coming Edition: backup car
2002 Chevy Cavalier LS Sport Coupe: In a Junk Yard
1995 Mazda Miata R-package Class=STR
Sponsored by: Kronos Performance

WPI Class of '12 Mechanical Engineering
WPI SAE Risk and Sustainability Management Officer

Im sure it is since the LSJ is supercharged. So then that formula would not apply to me?


GMR has got nothing on this

That formula does apply you just have to make sure you're using the flow rate for your static fuel pressure first


1994 Saturn SL2 Home Coming Edition: backup car
2002 Chevy Cavalier LS Sport Coupe: In a Junk Yard
1995 Mazda Miata R-package Class=STR
Sponsored by: Kronos Performance

WPI Class of '12 Mechanical Engineering
WPI SAE Risk and Sustainability Management Officer