Injectors [Archive] - GrandAmGT.com Forum

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OneFstGt
08-13-2009, 11:54 AM
What are the stock fuel injectors rated at?
I have a tuned pcm, does anyone know if i can upgrade to a bigger injector with my tune i already have to make some more power or would it even help.

lvemy3100
08-13-2009, 12:06 PM
stock 99' injectors are 19lb
stock 00'+ injectors are 22.5lb

if you change your injectors you will need your PCM modded for the injectors you wish to upgrade to.

if your current modified PCM is from MP Racing let me know and I will be happy to help you with this.

AaronGTR
08-13-2009, 12:13 PM
Not enough info. What year is your car? What mods do you have. Do you have a scanner and have you scanned the car while driving?


'99 and earlier cars have 19 lb/hr bosch injectors. 2000+ cars have 22.5 lb/hr delphi injectors. You can NOT just change injectors with out re-tuning the pcm. The car will not run properly. If you don't have enough mods and certain kinds of mods, bigger injectors won't help anyway. You have to be close to maxing out the stock injectors. The only way to tell is to scan the car while driving and data log the injector pulse width so you can see how long they are staying open. Then you need to calculate the duty cycle your injectors are running at based on flow rate, fuel pressure, and a few other things. Then you can see if you need bigger injectors. You usually don't want to run more than 80% duty cycle.

RC Engineering has some good info and formulas for determining injector sizing here. http://www.rceng.com/technical.aspx