View Full Version : Injector Lag -- affect on AFR?

07-12-2005, 02:38 PM
Hey folks, hoping you can help me out with some information with regards to injector correction, lag correction and thier effect on AFR and idle.

The car...

Redtop SR
Installed 600cc injectors (apperently these injectors have a lag of 0.72ms)

I made the correction into my PFC for the 600's (`62%)and then entered the difference of the old 370cc lag vs that of the new 600cc lag.

I was using the assumption that 370's lag 0.58ms so the difference would be 0.14ms for correction.

Long story short...idled poorly.

Started messing with the lag correction and got it to idle well at 0.72ms correction. I have no reason to beleive the injectors are off because they were rebuilt and I have the flow numbers.

My question...

I have an ZT-2 on the way. I am going to mess around with my idle AFR and wanted to understand is it better to set the lag in the right ballpark and mess with the injector correction...or leave the injector correction and mess with the lag?

Basically, I think I have a good base map for fuel and just want to ensure I am not rewriting the full 20x20 grid because my injectors are not setup right.

Anu help would be great.

07-12-2005, 05:08 PM
What are your MAP values for idle?
I have to run mine pretty high with 740s and 264 cams step 2

07-12-2005, 07:51 PM
Stock cams...

I am currently using an Enthalpy base...the fuel at idle is 0.95 if I recall.

Car idled perfectly before the injector change which I why I'd prefer not to mess with the map.

07-14-2005, 07:32 AM
Nothing gang?

07-16-2005, 01:32 AM
Yes, the injector lag time can affect AFR. It will not affect it much, but it will be enough to be noticeable.

If you have a ROM tune and the tuner did not know the correct settings for your injectors, you will either be really rich and get crappy gas mileage, or you will be lean.