'90 C4 fuel injectors and ECM
Thread Starter
Intermediate
Joined: Jun 2013
Posts: 48
Likes: 3
From: Troutman NC
'90 C4 fuel injectors and ECM
So, I've installed a Borla cat-back, SLP cold air induction, SLP runners and some hi-powered ignition goodies...At what point do I increase the injectors? I was told by a chevy tech dude that I could get away with up to a 31 lb. before needing ECM work done, does this sound right? I planned on maybe installing 28lb. injectors and a adjustable regulator, good idea or not? And incidently I installed the Spec stage 1 and their "heavy" billet steel flywheel, made the noisey tranny happy, and hooks real good....
Drifting
Joined: May 2013
Posts: 1,736
Likes: 31
From: Reno Nevada
Hogwash, that may be semi true for mass air cars, but not speed density. Your car is constantly adjusting fuel for a perfect 14.7 AFR. The factory memcal is programmed for a 22.1 lb injector. Adding 28 lb injectors would be beyond the ecm's capabilities to adjust fuel settings, and would run overly rich without reprogramming. Larger injectors are not needed until cam and compression, and head flow have been significantly increased.
Pro
Joined: Mar 2013
Posts: 628
Likes: 13
From: Indiana
So far you have listed nothing that would warrant upsizing the injectors. I agree you run the risk of going above what the ECM can handle. What I found is that the regular Fuel Pressure Regulators seem a little low on the pressure side and you can gain a little extra response by adding a adjustable regulator. I set mine for the highest recommended by GM and the car is a lot quicker with throttle changes.
Last edited by Klyde; Nov 13, 2013 at 06:29 PM.
Safety Car
Joined: Jan 2004
Posts: 3,783
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From: Northern California
