Blowby will reduce your octane, by a minute amount, and most people spend such a small percentage of their driving time at max boost, that It just isn't much of a problem.I had no catch can for 5 year/40k miles because I was on the OEM tune.
When I got the ECU flashed I also installed a JLT 3.0 catch can because the increase in torque will increase blow-by and contaminate the air intake with sludge at a time when Octane is critical. Blow-by can lower the Octane rating causing detonation events that IMO can lead to the dreaded Ecoboom.
This is 2k miles worth of sluge so I'd recommend a catch can when ECU flashing at a minimum.
I also had the air/fuel induction cleaning at 40k miles to clean the carbon from the system prior to flashing and installing the catch can. After the service black soot came out of the tail pipes and fouled out my O2 sensors so there was apparently a good amount of carbon built up after 40k miles.
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Most Ecobooms are caused by a bad tank of gas, on a pro tuned car, in conjunction with not monitoring the engine with an Accessport or by some other means.
Of course black soot came out of your exhaust. You sprayed a solvent down your intake, with the engine running. Where did you think it was going to go?You ran an induction system cleaner through your engine that not only cleaned your valves, but also your pistons and combustion chambers, and it wasn't the carbon that fouled your O2 sensors. It was the induction system cleaner. That's why you shouldn't use them on our engine and why Ford doesn't recommend them.