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Old 06-18-2008, 06:18 PM   #2 (permalink)
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metromizer, there is this thread. Also i have not searched the site for keyword, leanburn yet.

I have in the past made a little 2 channel box that used two 3v batteries and a simple variable voltage divider(megaohms, batteries last longer) to add 0.1 or 0.2 volts to the signal from the o2 sensors to the ECU. i rigged it up so it was switchable to be in series with the 02 signal or out (02 direct to the ECU). then i monitored the actual voltage from the 02 to see what really was happening. The best improvement i ever got was about 10%. (2 mpg) The ECU likes to see the 02 voltage cross over the .4v to .5v range every so often or it will turn on check engine light, so there is a limit as to how far you can go. before a check light. Some engines get a little better mileage around 16.5 to 1.(ref.johnnygrey)

another test i did is ref. in the above thread. using a zero to 10 ohm rheostat to drop the voltage to the injectors until the ECU can no longer lengthen pulse at which time the engine leans out. with this method i run open loop and unplug the o2 sensor and discount the engine check light. i have continuous read out on the o2 to avoid going below .25volts. obviously this brute force manual mode, your mileage may vary. (poor man's rheostat Craft shops sell heavy Ni-Chrome wire)

Last edited by diesel_john; 06-18-2008 at 11:29 PM..
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