Open loop

[Jim Nolan]

What would be the the up and the down side to running a modified LT5 continous open loop over closed loop? The car will be street driven and rarely raced. The primary mods will be full porting and headers.

[Pete]

There's really no big deal if it's tuned right.

Our Z's go into open loop anytime you wide open throttle it.

Closed loop is for cruising speeds.

Basicly if tuned right you don't even need closed loop.


Pete

[Demps]

Pete is right on...IF IT IS TUNED RIGHT.

I have one in a modified top-end car. The throttle response is instantaneous. The gas mileage in town is <12mpg and no better than ~20mpg on the road. NOT tuned right.

Ted

[XfireZ51]

What would be the the up and the down side to running a modified LT5 continous open loop over closed loop? The car will be street driven and rarely raced. The primary mods will be full porting and headers.

Jim,

No reason to use O/L. C/L brings additional parameters into play that are used for idle quality and part throttle cruise. Typically people will use O/L when they've installed more radical cams because C/L idle becomes more difficult to tune. Actually a way to deal with that but its not readily available.
If you're using the vehicle for cruise its preferable to use C/L.

[Locobob]

The big problem I see with running open loop full time is that you'll have to tune rich to be on the safe side since you are disabling your motors feedback system. Not exactly ideal for fuel economy, emissions, and motor cleanliness. I'm not aware of any advantages to open loop only, maybe one of the chip gurus can enlighten us?