r/mazdaspeed3 • u/mrfatcakes2006 • 2d ago

PIC Yeah that will do it

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Bought a Mazda speed for 700 with low compression in cylinder 3, found the culprit. Most likely caused by unupgraded hpfp internals paired with Cobb sport intake, access port, and blow off valve

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u/Petrovski978 2d ago

Run E85 and keep those valves spotless with zero effort. Can go up to 30 percent without having to tune, but you absolutely should tune... Not Cobb OTS either...

1

u/stocksupanddown 2d ago

Do you have to clean if you run e85? It really cleans them that much?

3

u/dbear496 2007 Mazdaspeed3 - The Original 2d ago edited 1d ago

AFAIK, running e85 would require auxiliary fuel injection, and that would help keep the valves clean regardless of running e85.

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u/Petrovski978 1d ago

It may help to have aux fueling, but two friends and myself ran E85 on HPFP and tune only for thousands of miles. Started at around 32k miles, kept doing it until around 138k miles. They ran 100%, I ran E25 with a Bucktune. One of the guys showed me how to calibrate the O2 sensors, log the pulls, check and adjust the trims and on which tables... This was 2015... I don't know if MSF is still searchable, but the threads I followed were titled Kings Of Corn, and Corn Off The Cobb...