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Originally Posted by TurboGTi
Does anyone have any experience with Rich AFR when meth is injected?
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When injecting all methanol, you will run much richer A/F. As a starting point, using the injector duty cycle near WOT, first figure out how much total gasoline your all your injectors are supplying (cc/min). Then, you must know the flow of alcohol being injected (cc/min). Start by decreasing the total fueling from your injectors by one half the amount of alcohol being injected, since methanol has about 1/2 the energy (BTUs) of gasoline. The real problem is what the wide band oxygen sensor is seeing. Since you now have a "new" fuel mixture of gasoline and alcohol, you also have a new stoich value. Gas is 14.7, methanol is about 6.4. Taking a ratio of the the total mix will get a proper stoich value. For my particular mix the new stoich works out to about 13.3 when injecting alcohol. For the wideband sensor to display this new stoich value you need to have the ability to re-calibrate the wide band oxygen sensor output to match. It can be a real bucket of worms when trying to tune to target A/F ratios.