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Title: MAF scaling, 8 bit axis limitations, and the K-box conundrum. Post by: ddillenger on April 24, 2013, 08:42:45 PM Alright, I'd like to hear opinions.
I've heard 2 trains of thought. PRJ: Switch to the K-box Phila: K-box software is requires too many tweaks to work (properly) with the NA s4 hardware, Stick with the M-box and convert to a 16 bit axis. I'd like to know more. In using an 8 bit axis we're limited to 191.25 given the conversion factor (FF=255, 255*.75=191.25). A 16 bit axis doesn't have this problem. Since pretty much everyone here is exceeding 191.25, what're you guys doing? I've yet to see a file uploaded that's had the axis' modified. I assume underscaling the MAF's so that max load is roughly 191.25 and working with that? I've seen files with proper MAF scaling (not underscaled) that threw P1557 codes when hitting boost despite no leaks. I assume that's the ecu reacting to the extreme loads. Can someone elaborate on this, or point me in the right direction? To be honest, I'd love to hear how you guys are running properly (not under) scaled mafs without hitting these restrictions. I've been contemplating switching over to me7.1.1 primarily for these reasons. All constructive criticism/commentary is welcome. If this is going to turn into an argument, or be filled with condescension, I'd just as soon have it ignored to be honest. Title: Re: MAF scaling, 8 bit axis limitations, and the K-box conundrum. Post by: nyet on April 24, 2013, 08:47:08 PM my two cents: P1557 codes are not from rl limitations.
the rest is up for debate; i've not yet experienced any issues with underscaling maf values near the rl limit. that said, I have not tuned a 2.7t with over 500whp. Not sure what happens out past there. Title: Re: MAF scaling, 8 bit axis limitations, and the K-box conundrum. Post by: ddillenger on April 24, 2013, 08:52:53 PM my two cents: P1557 codes are not from rl limitations. Well search as I might, I've yet to find anything that I felt adequately explored this. the rest is up for debate; i've not yet experienced any issues with underscaling maf values near the rl limit. that said, I have not tuned a 2.7t with over 500whp. Not sure what happens out past there. The debate is what I'm interested in. There's more than one way to skin a cat, but thus far all that I've seen discussed (and not in detail) is MAF scaling to alter the load the ecu sees. I know there are guys on here that are surpassing these limits. Title: Re: MAF scaling, 8 bit axis limitations, and the K-box conundrum. Post by: prj on April 25, 2013, 12:19:09 AM 551K also has annoying boost calibration, but an ASM hack is easy to revert to normal behavior...
Title: Re: MAF scaling, 8 bit axis limitations, and the K-box conundrum. Post by: nyet on April 25, 2013, 08:08:04 AM Well search as I might, I've yet to find anything that I felt adequately explored this. In general (assuming the hardware is 100%), positive deviation is the result of rlmax being too high at low rpms, not from any rl limit. I'd have to see a log to know for sure. http://s4wiki.com/wiki/Tuning#Positive_deviation Title: Re: MAF scaling, 8 bit axis limitations, and the K-box conundrum. Post by: britishturbo on April 25, 2013, 09:42:37 AM Phila and I have talked about this a few times. It's on our long term goal of things to do - add 16bit lookup to the M-Box lol.
In the meantime I have been using the 5120 hack with non scaled MAF and I'm having very good luck with it. And don't forget that it's only some of the table lookups that are 8 bit... load is still 16 bit internally. I have ME7Logger logging the 16bit version of load so I can at least see exactly where it's at. Title: Re: MAF scaling, 8 bit axis limitations, and the K-box conundrum. Post by: phila_dot on April 25, 2013, 11:03:32 AM The lookup itself is there; it just isn't being used in some cases where rl was choosen vice rl_w (obviously).
I think I like my alternate plan better though ;D Once I get fully back up and running, I will incorporate this with the completion of the 5120. Title: Re: MAF scaling, 8 bit axis limitations, and the K-box conundrum. Post by: britishturbo on April 25, 2013, 11:04:56 AM The lookup itself is there; it just isn't being used in some cases where rl was choosen vice rl_w (obviously). I think I like my alternate plan better though ;D Once I get fully back up and running, I will incorporate this with the completion of the 5120. Hmmm text me and remind me what that was? lol |