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Old 01-24-2018, 10:44 AM   #67 (permalink)
Calibration Engineer
Join Date: Jan 2010
Location: Canada
Posts: 86

Subie - '00 Subaru Impreza STi JDM
90 day: 22.49 mpg (US)
Thanks: 1
Thanked 17 Times in 14 Posts
Pulse and pollute is a bad deal on the 3A92. I had over a week on the engine dyno with one and the size of the engine is well matched to the optimal BSFC. The downside is with such a small engine you lose cat light off and it takes a while to get back. Stick an EGT probe into the cat and you can monitor this. A 5 gas analyzer is a bit spendy for a tinkerer, but you can see how bad the emissions become.

With the cat off, you're releasing huge amounts of pollution and I feel that P&G will most likely clog your cats in short order. The factory design was centered around 65mph, so maybe changing the final drive would help a bit, but it will be expensive.

If you have the tools to read and write the ECU, then I can give you a calibration for increased fuel economy. I never finished validating it for emissions, but I suspect it will improve efficiency with minimal increases in NOX emissions.


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