[arghx7]

Originally Posted by regal

Based on the info posted in this thread unless your dealer has an IT forensics team as long as your flash count is less than your dealer visits it would be very unlikely to have a warranty denied. I think a good tune should prevent warranty work.

Again, I'd hesitate to call myself an expert but I've never seen a "flash count" on a dealership tool or OEM tuning tool. Does somebody have any proof that this even exists in anything other than the ECU manufacturer's internal tools? Got a screenshot of a "flash count" in Techstream? I'm trying to understand where this idea is coming from.

For example I know this car uses the cam timing to suck exhaust back into the combustion chamber (modern EGR), basically there are sacrifices the OEM makes for regulations and for mass production, these are things the consumer should be able to fine tune.

It's called dethrottling. I know this sounds strange, but it works on the same basic principle as cylinder deactivation: open the throttle more so that your pumping work decreases. In cylinder deactivation, it's accomplished by shutting off half the cylinders. With charge dilution like EGR, you are adding in extra air to account for the additional unrburnable mixture. This requires the throttle to be opened further, reducing pumping work. Any engine with variable cam phasing does it. Do an AVCS sweep at a given low-load point, and you will see brake specific fuel consumption go down with more phasing.

With Scion USA burying their heads in the sand and not releasing the latest OEM flash for the transient ignition retard issues which may help with the DI issues, it really makes custom tuning something I want to do sooner rather than later.

It's probably sitting in some dude's Outlook Inbox right now, or making its way through three departments' tracking spreadsheets. Maybe it's on the agenda for the next insufferable meeting between two comparable departments in Toyota and Subaru. The guy in charge of that could be on sick leave. The reason behind it is probably more mundane than someone proverbially "burying their heads in the sand."

I read a few scary posts with graphs that showed how much knock the stock tune gives (not just after shifting either), the OEM tune relies way too much on the knock sensor to pull timing after the fact, its sloppy.

For a completely stock car people say they want the best fuel economy possible. That means running as much timing advance as possible and trusting the knock control system. There's nothing unusual about that.

A good tune doesn't rely on a knock sensor, that's just there for as insurance. But what do the OEM's care? They only need the engine to last to 60k miles.

If the ECU pulls too much timing due to poor tuning of the knock control, the cat will overheat. Then the vehicle will fail the long term in-use emissions testing and the OEM could get fined. Durability requirements are getting stricter and stricter due to CARB regulations.