DFCO Limits - Third Generation F-Body Message Boards

Bones232 · 04-02-2006, 02:44 PM

I am curious as to what the "safe limits" are for DFCO. Obviously DFCO cuts off all fuel flow once it's settings are satisfied (I see my afr go to 20:1 and EGT's drop).

I've noticed that the band where all settings are satisfied is narrow. It seems DFCO, in stock form, is only active at low rpms between 850 and 1350 rpm (please correct me if I'm wrong).

In my particular case, once in DFCO, vacuum builds to the point where it trips the low map threshold for that event. This causes the ecm to constantly move in and out of DFCO during prolonged decels. The high vacuum is probably a result of my low IAC vs CTS values and nonexistant TF steps.

Now that you have read this far, here are my questions;
1. Is 20:1 ok in DFCO? (no fuel is no fuel)
2. How high can DFCO be safely used?
3. Is my assumption of the DFCO's operational band correct?
4. How low of a map value is safe for DFCO?

The Sun's out gotta go tune

(A pretty rare event in CNY)

RBob · 04-02-2006, 04:32 PM

The RPM parameters such as: between 850 and 1350 rpm, is for hysterisis. DFCO will be entered if above the higher value, and will exit at/below the lower value. When not in DFCO the engine has to be above the higher RPM value to be able to enter DFCO.

RBob.