Open/Closed Loop Operation

Quick and easy (I think question): When do L67s switch been closed-loop (reading the O2 sensor) and open-loop (maps only) operation? Obviously, they use open-loop when at WOT and on a cold start of the engine...but I'm curious more about where exactly it switches over (load based? tps based? cylinder airmass based?) Is it safe to say that whenever I see the Command AFR drop from Stoich, the car is reading purely off of fuel maps? ...that would make sense to me to use closed-loop to keep the car at 14.7:1 (or wherever you set it), and then jump to fuel maps as soon as you richen up from there.

There are 2 tables in a GTP .bin file that control the OL/CL functions.


1.) Delay vs. Engine Coolant Temp.

What this does is says "if the engine coolant temp is xxx degrees, it will switch to closed loop after xxx amount of seconds." Obviously, the colder the motor, the longer the wait time for the transfer from OL/CL.

2.) Closed Loop Enable ECT

This just says "if the coolant is above xxx degrees (I believe the stock table is set at 68*F) then it will automatically enable CL."



Hope this helps

Once you engine is warm and the 02 sensor is at 600* it will be in closed loop until you hit pe mode. Power enrichment kicks in at different times depending on what your car is tuned for.

Boostd1 - thanks for that info. I'm less concerned with when the engine goes from OL on a cold start to CL for normal operation, and more concerned with when - during warm engine conditions - the engine switches back and forth between OL and CL.

01GTP - Okay, so is PE mode the only time it reads OL?

If all of the senors are working correctly yes. After the engine enters cl it stays in cl untill you get into pe mode If think its like 60% throttle or so on a stock pcm.

Originally Posted by porshuh

Boostd1 - thanks for that info. I'm less concerned with when the engine goes from OL on a cold start to CL for normal operation, and more concerned with when - during warm engine conditions - the engine switches back and forth between OL and CL.

01GTP - Okay, so is PE mode the only time it reads OL?

Under warm conditions, it goes into CL after a certain amount of time. I think warm is just a few seconds.

I think the engine temp has to be around 100*