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Old 11-16-2022, 02:18 PM
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Leecbr Leecbr is offline
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Join Date: Aug 2010
Location: West Jordan, UT
Cobra Make, Engine: Factory Five MK4 427 roadster
Posts: 172
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Default I've been running FI without 02 sensors

Hello everyone, I just wanted to share a positive experience with running a Fuel Injected engine without 02 sensors. I currently have a Factory Five MK4 with a rebuilt donor motor from a 2003 Mach 1 mustang. I bought the car 80% done and I noticed the builder had no provisions for 02 sensors. After completion of the build I was worried about the missing 02 sensors.

After searching various Mustang forums I noticed most of the guys deleted the 02 sensors due to modifying the exhaust to long tubes and cat delete.

So I asked a local tune shop (Premier Performance) and they stated that it can be done tuning without 02's.

The simple answer is the EEC-IV and EEC-V ECU can run without 02 sensors. It uses the mass airflow sensor, intake air temp sensor, and baro sensors to adjust for atmospheric and temperature changes. The stock EEC-IV and EEC-V will go into closed loop above 140F coolant temp and go into open loop above a 70% engine load. To run without 02's the tune starts with the combination of closed loop and the adaptive learning which allows the ECU to maximize fuel economy and maximize emissions.

When tuning turn off the adaptive and forced the computer to stay in open loop then adjusted the fuel tables and MAF function. Once the AFR match the ECU command AFR they turned the adaptive and closed loop ability back on. I understand the computer will try to cut timing to richen up the fuel. When I used my SCT X4 scanner I noticed the spark advance was set to 10. I'm assuming this was set to compensate for the computer wanting to cut timing.

I've accumulated over 4k miles without any ill effects. The cobra idles great and traversing the canyons without any issues.

Last edited by Leecbr; 11-16-2022 at 02:28 PM..
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