Customer just dropped off a freshly built F-body project for tuning. It is a 408 with a D1SC. AFR heads, LSX/90/90 and 750cc R/C injectors. I just wanted to get the car to idle so I started with a stock file and scaled the injectors as noted. I have never used the RC injectors before so I took the 750 cc and divided it by 10.5 to converter to lbs/hr. This equated to 71.428 in which I dumped into the spreadsheet to come up with the IFR slope based on the pressure being used.

I also set the timing to 25 degrees at idle to provide some stability, set the fans to come on earlier and loaded the tune. The car was VERY hard starting and once running was idling with a AFR between 18-25:1 !

Once the car went into CL the LTRIMS where buried in the 12-18 % range. The motor has a decent size cam, especially for a blower motor so some lean idling is expected due to overlap. It was even that lean while holding the rpms at 2500-3500 rpms so it seemed that it was globally lean. What I wanted to try was to fudge the IFR to increase the fueling globally just to get the car to run. I couldn't remember if raising or lower the IFR increased or decreased fueling.....Seem to remember that decreasing the values increased the fuel.....need confirming...

I was also wondering that since the blower is moving more air at idle (under vacuum) that the increase was leaning the stock VE table.....but wouldn't the MAF at least jump in a makeup some of the error?

Just finished a 04' GTO 377 with a D1SC and it ran decent on stock values and needed very little tweaking to get it perfect. I have never seen a car run so damn lean like this. It is definately lean as it has a nasty popping lean mis and throttle response has holes in it. Its lean.

Anyone use these RC 750cc injectors? I am assuming that the math is done right and I am not off as it seems.

Looking for some insight!

Thanks

Howard