EFI, Alpha-N vs Speed Density fueling Strategies

RacingRicki · 03-09-2014, 12:53 PM

David,

You mentioned a racer that is running in speed density open loop. If it is open loop, how is it that the ECU is compensating for air changes? I thought open loop meant that there was no compensating going on.

I run the "classic FAST" system in Alpha-N mode open loop. With that setup, closed loop would use the o2 sensor to correct the fuel. In open loop it doesn't. How is this different with speed density? Does speed density use the o2 sensor at all?

Also, I was told that even though I run in open loop Alpha-N that there are tables that I can't see that are compensating for barometric changes much like a carburetor does naturally. Is this true?

03-09-2014, 12:53 PM	#11
RacingRicki Sponsor Join Date: Sep 2005 Location: Colorado Posts: 106 Likes: 0 Liked 0 Times in 0 Posts	Re: EFI, Alpha-N vs Speed Density fueling Strategies David, You mentioned a racer that is running in speed density open loop. If it is open loop, how is it that the ECU is compensating for air changes? I thought open loop meant that there was no compensating going on. I run the "classic FAST" system in Alpha-N mode open loop. With that setup, closed loop would use the o2 sensor to correct the fuel. In open loop it doesn't. How is this different with speed density? Does speed density use the o2 sensor at all? Also, I was told that even though I run in open loop Alpha-N that there are tables that I can't see that are compensating for barometric changes much like a carburetor does naturally. Is this true? __________________ RacingRicki