Fuel injection? Open or Closed loop?

DrHP · 08-08-2012, 10:50 PM

Gentlemen,

The question of closed or open loop is not really valid when the engine is using a narrow band O2 sensor. The stock systems normally use this narrow band sensor that is accurate only in a very narrow target area of about stoichiometric (14.68:1 with pump gasolne).The wide band sensors can be used with the appropriate control system, but I would think you want absolute control to be consistanrt. Some of you racers hit it on the head, mentioning that at WOT the system had better be in open loop, using the base fuel tables with its modifiers. The operational parameters regardng PE and the closed loop threshold are probably the areas that are highly tuned (along with base fuel and spark), that the successful guys paying attention to. Forced open loop would cerntainly be my choice!

Just an old racers two cents, Dennis Baccus
Former F/S record holder - 1969 Z28,
Current calibration engineer on GM MEFI systems and engine builder

View Poll Results: Fuel injection? Do you run in open loop or closed loop
Open Loop	80	65.04%
Closed Loop	43	34.96%
Voters: 123. You may not vote on this poll

08-08-2012, 10:50 PM	#11
DrHP Junior Member Join Date: Feb 2011 Location: Walla Walla WA Posts: 8 Likes: 0 Liked 0 Times in 0 Posts	Re: Fuel injection? Open or Closed loop? Gentlemen, The question of closed or open loop is not really valid when the engine is using a narrow band O2 sensor. The stock systems normally use this narrow band sensor that is accurate only in a very narrow target area of about stoichiometric (14.68:1 with pump gasolne).The wide band sensors can be used with the appropriate control system, but I would think you want absolute control to be consistanrt. Some of you racers hit it on the head, mentioning that at WOT the system had better be in open loop, using the base fuel tables with its modifiers. The operational parameters regardng PE and the closed loop threshold are probably the areas that are highly tuned (along with base fuel and spark), that the successful guys paying attention to. Forced open loop would cerntainly be my choice! Just an old racers two cents, Dennis Baccus Former F/S record holder - 1969 Z28, Current calibration engineer on GM MEFI systems and engine builder