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Old 06-18-2008, 05:59 PM   #1 (permalink)
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Join Date: Jun 2008
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Fooling the ECU to burn lean...

Is there a simple way to fool my ECU into reducing the amount of fuel it tells the injectors to pass? Sort of a flip of the switch 'lean burn' mode?

Here's how I would use this lean burn mode, the goal is use less fuel:

I'm in top gear, the road is flat, the engine is humming along at 2800rpm in closed loop mode and under a constant load while traveling at 65mph. I'd flip a switch, that puts the engine in this 'lean burn mode', maybe an LED on the dash lights up (to remind me to switch it off while climbing a grade).

I would likely need to experiment to find what my engine likes, how much fuel I could take away under 'lean burn' trim. Maybe I would read voltage from one or both existing o2 sensors, maybe I would add a stand alone cylinder head temp probe under #2 spark plug and gage on the dash (to keep from melting the thing down).

My '96 (3) Cylinder TB injected engine is basically stock with (2) 4-wire O2 sensors (maybe the ECU averages between the two?). The car retains it's stock cat, it needs to pass California emmisions every two years. I am no electronics guy, I only know a little about the way EFI works, and have only used O2 sensors to keep an eye on carb jetting on a race car... a single wire narrow band that gave only marginally useful feedback (just another tuning tool like reading spark plugs). I can wire, solder, etc, but switching over to a Megasqirt system is out of the question.

Just brain storming here... please chime in with ideas and concerns, I'm thick skinned (hopefully not thick headed)

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