How To Change A Fuel Injector On A 2014 Chevy Cruze

What is Closed loop vs. Open up Loop o2?

How to tune and set up these parameters

Contributed by: Enginebasics.com

A term you are bound to run beyond when tuning an EFI fuel injection ready-up, is the term "closed loop o2". The purpose of this article is to explain how open and closed loop o2 works and how to tune and change these tables.

O2 Sensor Background

The o2 sensor is the sensor located but after the frazzle manifold where all of the frazzle gasses have been collected into a single frazzle pipage. This way the sensor can get an accurate reading from all cylinders of the motor. There are two types of o2 sensors, narrow band, and wide band. While closed loop o2 can be used with a narrow band sensor, its accuracy is not fine enough to consistently rely on its reading. For this reason I would suggest only using closed loop o2 with a wideband o2 sensor. To be fair though, I would suggest that any high performance engine be equipped with a wide-band o2 sensor, and that this should exist considered a must accept. This sensor is a 0-5v sensor that can accurately read the air to fuel ratio of the exhaust gasses.

Defining Open Loop and Airtight Loop o2

Open loop is when the ECU is not referring to the o2 sensor for feedback. Meaning that the o2 sensor might every bit well not be in that location, because the ECU is non using it to modify its timing and fuel maps. If your request yourself why the ECU would ever want to do this? It is considering there are times when you desire the motor to run a set amount of timing and fuel, no affair what the conditions. For reference, about OEM cars are tuned to run closed loop o2 on partial throttle driving to get the best gas mileage, and so run open loop on broad open throttle (WOT) to exist certain the motor runs the safest it tin can, and that the factory fuel map is not modified in any way. Closed loop is when the ECU does refer to the o2 sensor for feedback. Using the o2 sensor the ECU will modify its fuel table based on the readings the o2 sensor is seeing. This is important in maintaining a perfect A/F ratio as there are so many variables affecting the tune of a motor at whatsoever given time. For example, air temperature, altitude, humidity, and so on.

Tuning Closed loop o2

Virtually stock and aftermarket ECU's allow you lot to tune the adjustability of closed loop o2 operation. If you take hacked into the stock ECU to change calibrations then this might be more difficult to melody, but on near aftermarket ECU's it is very straight forward. Some of the options you will have the ability to change are:

1. The Percent (%) of fuel that can be added or subtracted from the fuel map.

two. The coolant temperature when closed loop o2 will begin.

3. The engine RPM when airtight loop o2 will begin.

4. Weather condition when closed loop o2 should be turned off.

5. The target A/F value based on load or MAF cfm, and engine speed.

Certain ECU's allow for more than or less tuning of this parameter. It should be pretty directly forwards what each of these values practise. One thing y'all will desire to brand sure you do is TURN OFF Closed LOOP O2 when you are starting out tuning the vehicle. This is because equally y'all are trying to go a skilful base fuel map, you will want to see the actual A/F value's your map is producing. If you leave o2 feedback on, then you will exist seeing modified values, every bit the ECU itself is trying to punch in your target A/F ratio. Once y'all have fully tuned the fuel map to be as close every bit you lot tin can to your target A/F values, and then you volition desire turn on closed loop o2. Yous will notice the map to incorporate even smoother A/F ratios, and be spot on now that the ECU is calculation a little here, and taking away some at that place, to provide the perfect melody.

Conclusion

Some tuners or users are scared of o2 feedback, because of the ability of the car to lean itself out. While this is a possibility, well-nigh tuners tin melody the stock fuel map to be and then close to accurate, that they just allow closed loop o2 to change at max 10% of the fuel map. Besides, if the user is worried about the o2 sensor going bad, and giving false readings, I often encourage them to but modify out the o2 sensor every 3-5 years just as a precaution. When wideband sensors have become as cheap equally $eighty bucks, it just seems similar a sound investment when at that place tin can be up of thousands of dollars nether the hood.

Please make sure your wideband o2 controller is upwardly to appointment and the sensor is reading properly. Here are some current ones on the market:

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Source: https://www.enginebasics.com/EFI%20Tuning/Closed%20Loop%20o2.html

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