Question:

Since a MAF's transfer function must be calibrated with respect to a MAF housing of fixed volume to be accurate, wouldn't you need to know in advance the intended tubing diameter and pre-program accordingly? If we match the transfer function of an HPX to a Mitsu MAF when that HPX is situated in a 2.5" tube, that will equate to a very different air mass if we switch that HPX to a 4" tube.



Any sensor is potentially a bad fit if data critical to its accuracy is ignored. Without IAT, any hot wire or hot film MAF is incomplete: PV=nRT


'A little programming' is required for the SD mod, but that also adds another layer of calculations and apparenty doesn't work very well either. If another $150-200 saves weeks (if not months) worth of programming and tuning hassles, I feel it's worth it.

For Mellon, myself, and others who will surely follow, the factory MAF is a limiting factor that clamps a ceiling on how much power we can obtain from our setups. For us, resolving this is a genuine need, the only alternative being a standalone. We couldn't care less if the upgrade is a draw through, blow through, or whatever, so long as it doesn't amount to a cheap, unreliable band-aid. A few hundred bucks is a drop in the bucket of what it takes to get to the point whereby this becomes a need. If this was just an exercise in inconveniencing myself in pursuit of 'ricer hawtness', I wouldn't waste my time.

 

My build, when it is complete here in about a month will also be pushing the ceiling of the ECU, thus my interest in a SD conversion, or some sort of MAF replacement.

 

hey get the PMAS or HPX, i hear they're good seriously. aem has an excellent turn-key ECU replacement thats SD capable and proven too. lots of options without the wait for sure. that might be the best route for you rather than waiting.

as for paying to play, it's much cheaper and easier to just buy a turn-key unit plain_and_simple. R&D costs a lot more and also tests your patience/skills/etc. it's not for 98% of the joes out there. thats why i'm 'that guy' along with some others here too. hell, i gotta do something to keep my 'brain from dying' as bez said. i switched jobs...and this one requires the IQ of a banana(not really)--but its fun. thats why i'm here with my bs comments, no tuning knowledge, and minor contributions.

lots of interesting views. gotwheelhop, if you wanna wait a little bit, there probably will be an opensource/tunable/documented solution for you. you could also order a AEM or the like and have it next week. the stock MAF setup might even be fine if scaled/tuned right.

there's a cycle of tuning that goes on. new vehicle/new piggyback. then you get your ecu+'s and utechs. alongside that, theres the standalones. then you get the actual ecu hard-coded patches. the utecs and ecu+'s go the way of the dodo because the hard coded patches do the same thing, have no wiring and (for internal calcs/adjustments) have amazingly low latency. in our generation, ECU techology is paralleling some of the more advanced aftermarket ECU's while beating the mediocre ones (once great in their own time) outright. we haven't reached the limit of the EVO8/9/X ecu yet. it's amazing how "open" the original developers left it as i dive even deeper into it.

it resets with the next model lol. it starts with vishnu's piggybacks haha j/k.

oh god way off topic now/sorry.

is there a need: no, not really

is it possible: too damn easy (a couple of different hotwire mafs, pipes, some code that could be whipped up in a night--maybe less for some, a dyno or a landing strip lol/test mule)

will it help power wise: don't know/compared to what

is it cool: yes

EDIT: about the post turbo setups, i always thought it was created to help make VTA BOV's drivable. it does do it fine, but it skews how the stock ECU works if used with a stocker. having to worry about hoses coming off or boost leaks should be solved before driving the car/provisions need to be made. a mechanical fix is the fix for those, not a fancy MAF setup. but good info from all on this thread. i hope to have this done before i 'take a vacation' again in a couple of months. lol. if not whatever. great ideas and experiences everyones coming up with though.

 

I have been in the game more than long enough to know about an AEM box. Heck, I think there are few people who post actively in this subforum that don't.

I already was reaching the point of drivability issues with my car. Going to really big boost, as I plan with the 67mm I have coming in will just compound the problem. I love the functionality and the simplicity of the interface with the stock ECU however, thus my reluctance to just jump straight to a standalone system.

Ironically enough, Mrfred was here in Vegas a few nights ago, and we had the exact same discussion as what I just quoted over a few beers.(if you ever meet one of the ECU gurus in person, buy them a beer. we all owe them that much) We were discussing the lack of true opensource patches within the Subaru community. Most of the Subie guys are content with tuning their car to run with basic bolt on's. Most of those bolt on type's run a flash of some sort. Next up are your AccessPort and UTEC guys...they run a little bit more crazy setups, but again, they aren't utilizing the power that their ECU's have.

The Evo community on the other hand, didn't get as much support(e.g. none) for the UTEC when it first came out, and you also had very programming savvy owners that wanted to dissect it. Thus we are now standing on the threshold of converting a stock MAF ECU to run speed densityand/or a larger, less finicky maf setup. I love how adjustable the stock ECU is, and I want to see it reach it's absolute limit before going to an aftermarket box.



Exactly. Start with a mule, and end up with a horse.

 

Why is SD not a good idea? It seems like everyone one wants it, so I'm surprised by your comment.

 

i reckon SD is harder to tune.

VE map will be a real pain to get right - and isn't static with mods.

 

yep the two last great hurdles to make the stock ecu as powerfull and as desired as an aftermarket unit are SD and antilag,
believe me I Tune cars over here and the tephra mods are a great attraction to stick with the oem ecu
but more and more people are forging their engines and wanting to run higher boost and want antilag so they ditch the oem ecu and shell out thousands on an aftermarket ecu
and this sickens me when the oem ecu is cabable of all that and more
if ya just sit back and look what it can do now
nearly all of the important tables are defined
we have nlts
valet mode
knockilght
switchable maps for e85

all thats missing is antilag and sd and then the oem ecu will surpass the aftermarket units by far

 

I'm working on a full disassembly of all the MAF code from the interrupt thru the load calc to the injector pulse width. I have two aims with this - 1. to find any remaining load limits as the 380 load limit I found the tables for appears to maybe work on one IX, but not on an VIII. 2. to do a completely understood SD conversion.

I find SD is fine to map and to drive if it is done well, on cars with big turbos and dump valves it drives smoother I find. It has bad press due to lack of adjustability in the past with breathing mods, and poor starting, idle, transients, emissions etc.

Not sure what is missing on antilag? I did the disasm for the JDM models that have the secondary air system stock, presumably people can add this code to the models that don't have it stock? The banjos can be enlarged to put more airflow through.

 

for proper antilag we need to be able to retard the ignition more than -10
we also need a patch for it to all come together,
ie retard timing -20 no fuel cut on throttle lift off and idle speed set to 1600rpm all this in one patch so we can switch it on and off
but some people thing this is a waste of time unfortunatly,

anyway as far as SD is concerned Bez has this tested and working so why do we need to reinvent the wheel all the hard work is done
all thats needed is disassemble the bez rom I am sure he has put comments into the code where he made changes and copy the code out to the rest of the roms like tephra does for his patches finding the proper places to slot the code into is probably the hardest bit,
If I was inteligent enough to be able to do it this way I would, but im not

 

In a nutshell, its a shortcut for the lazy.. It has the potential to work "okay" but there's a reason very few OEM systems still use it, I've owned numerous cars over the years, and many were speed density systems (either OEM or aftermarket) and lets just say its a step up from a Carburetor, but a huge step down from a proper MAF equipped and tuned system.

GM Hot wire setups have issues, but ford and later GM, and most newer Japanese use Hitachi sensors or similar/identical technology which works amazingly well pre or post turbo.

Speed density is basically a glorified electronic carburetor. Might as well throw an electronic carburetor from an 83 z28 on your car.

Sorry for my harsh and opinionated answer, but I'm very tired of hearing the answer to every post to swap to an AEM to get speed density. I feel very strongly that if you want to drive a car on the street, then do it legally or GTFO as its the tools with the Illegal hardware that make it more difficult for the performance industry. Its one thing to live somewhere that its not required, I live in a county that doesn't require any emission controls yet I still wouldn't run Catless or an EMS.

I don't want to turn this thread into a SD or AEM argument, so I won't acknowledge further SD posts, as this thread appears to be asking for an **ALTERNATIVE MAF SOLUTION AND STOCK ECU**

 

My recollection is that Bez' had said that there were some things that he was not sure about with his patch. The Evo ROM is incredibly complex, and it could take a very long time to create a completely understood SD patch.

 

BTW, MrFred, Sorry for jumping all over you on that one.

 

It would be interesting to see someone write a brand new rom from the ground up though.. unfortunately in doing that I'd suspect if would be no better than an AEM swap.

 

yep I fully understand what you are saying
but surely its a good starting point
im not saying its perfect but maybe with some proper testing and understanding of the changes he made ye might be able to perfect it

anyway as far as SD is concerned its not without its problems
I have an evo 6 tme here at the moment running on an Autronic and the owner wants me to convert it back to an evo 7 ecu
as the car is his daily driver and he cant live with the roughness of the Autronic,
so maybe jack is right we need to look at something in between,
I suppose the big attraction to SD is your not limited to the size or range of the maf in your car therefore with aftermarket ecu's you can run bigger turbos with more airflow

 

No prob. I didn't take it personally. I just don't have enough experience with SD vs MAF to know the pitfalls.

I'd bet that jcsbanks is using Bez' patch as a reference (at least that's what I'd do), but there is still much to understand with the stock ROM code.