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#87: 02-08-2014, 11:43 PM
Disabling Closed Loop to Open Loop Delay
covertrussian's Avatar
Title: MPG Tuner
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Car: '05 LGT, '12 OBP, '00 G20+T
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Upgraded to the A2WC522N bin, was at A2WC510N, since I was going back to a 100% stock tune, figured I would play with CL to OL Delays.

Closed Loop to Open Loop Delay is found on USDM's mainly (it's believed that it's there for emissions reasons), JDM tunes that I've looked at had it disabled. What it does is keep the ECU in closed loop while you are flooring the car for set amount of time, aka lean while in boost! This leads to burnt valves on bone stock cars. Going to any stage 1 tune should disable CL to OL Delay (by zeroing out the values).

Lets take a look at the VD graph, look at AFR's.

As you can see with the 100% stock tune, you are staying at high 13 AFR's while pushing 12ish PSI. This is also happening while you are at peak torque, where the engine is the most susceptible to knock.

By disabling Closed Loop to Open Loop Delay (by setting it to all 0's), the AFR's just about instantly dip to 11's, now stock O2 sensor is very inaccurate below 12:1 AFR, thus take it with a grain of salt. But as you can see the engine welcomes the richer AFR's by gaining you 20ft-lbs of torque.

Do notice the peak horsepower is "down", which I would blame a slight road inaccuracy for, thus nothing to sweat about.

Moral of the story: ALL TURBO SUBARU's should have closed loop to open loop delay disabled if they want to save their valves and gain some power while they are at it!

Last edited by covertrussian; 11-14-2017 at 09:20 AM..