date not saved · #1
I see it referred to alot here and in the FSM. What is open lop compared to closed loop when referring to the ECU?
Open VS. Closed loop
This thread was saved without dates. "Around May 2005" is estimated from neighbouring threads.
date not saved · #2
It referrs to the fueling of the vehicle.
Open loop is when:
- starting the engine
- when the engine is cold
- hard acceleration
- wide open throttle
Electrical sensors (like the O2 sensor) are ignored and the ECM relies on programmed fuel base maps for when and how much to inject.
Closed loop is when a warm engine is run at a constant RPM. The ECM reads all available sensors and makes the best decision on the amount of fuel to inject. This efficiency in injection increases gas mileage.
If you're driving down the highway, you should be in closed loop mode. If you're jumping from stop light to stop light in a busy city, you will stay in open loop mode.
date not saved · #3
freakin awesome! Is it POSSIBLE for the ECU to malfunction and stay in one or the other mode?
date not saved · #4
freakin awesome! Is it POSSIBLE for the ECU to malfunction and stay in one or the other mode?
Depending on type on malfunction, the system automatically reverts back or stays in open loop. If a major sensor such as the Air Flow Meter takes a dump, then the ECU goes into "Limp Mode". I have never seen a condition where the systems stays in closed loop, tho. Don't think it's possible.