FAST VE Numbers

[DOHC Vobra]

Just wondering if anyone's had an experience similar to this.... I recently installed a FAST ECU onto my '97 Supercharged Mustang. I created a custom adapter to use the stock engine harness, and so far, everything seems to have gone well (the car starts and drives well).

Now for the wierd part, for some reason or other, I'm having to put numbers like 100-110 in the lower portion of the VE map just to make the car idle. Any lower and the car starts to go lean. (BTW, this is with a target 14.7 a/f ratio in the A/F ratio sceen)

Is it just me, or do those numbers sound whacked out???? Any ideas what might be happening??? I've checked my injector size (lb/hr setting) and it's correct...

Thanks for any info!
Justin

'97 Cobra Coupe #35
http://www.guieectuner.com

 

[Craig Smith]

You probably won't be able to idle this motor at 14.7. On a blown motor with any sort of decent cam in it at all, you are probably looking more at about 13.0 to 13.5 or so for a happy idle. Try changing the target a/f ratio at idle and see where you get with it.

 

[DOHC Vobra]

Thanks Craig!

I'm actually running stock cams with acentrifugal blower, so there's no real boost till about 3500RPM...I figured I might be able to run about 14.7:1 since at idle, the car is basically a stock setup... Lowering the Target A/F ratio down to 13.5 or so will allow me to lower the VE numbers to something more realistic though...

Thanks for your help Craig!
Justin
'97 Cobra Coupe #35

 

[Craig Smith]

The boost isn't the concern, it's the drag that the blower puts on the engine. You make about 0.0001 horsepower at idle so you need all the help you can get.

A friend of mine did a neat little test. He dynoed a blown motor without the belt on, then attached the belt but none of the ductwork. this test would show how much power it took just to spin the blower. It wasn't a real big blower either, but it took 150 hp just to spin it!