[turfdoc]

I was messing around with my scangauge today and I noticed when I let off the throttle the scangauge said I was in open loop mode. Now my question is, is the truck supposed to do that?? I thought that it only switched to open loop mode above 3000rpm.

Thanks,
turfdoc

 

[LanNinja]

No, mine does that too. I think it's normal. The ECU switches back and forth at certain RPMs I guess.

 

[noladude]

The ECU will also enter open loop under deceleration and braking...I believe that it's called "fuel cut". I noticed it when I started tuning my calibrator. Initially, it was a PIA trying to narrow down when the switch would occur, but after a few weeks of closely monitoring the scanguage, I figured it out.

 

[wjdunn3]

Yep, fuel cut mode. It's exactly what it sounds like. The ECU cuts off the fuel injectors so that all you engine is doing is pumping air.

If you have an AFR gauge, you see the A/F ratio go to max lean (20+:1)

 

[turfdoc]

Oh ok I thought I had done something when I hooked up my MAF CAL or something.

Thanks
turfdoc