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Old 04-15-2010, 04:16 PM   #1
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Default MS with maf question

If I were to use a hot wire MAF would I have to wire it into the connector to the MS or does the wiring bundle here
http://www.diyautotune.com/catalog/m...5daab16773a497
already have the needed wires for the MAF?
Thanks for any info
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Old 04-15-2010, 04:24 PM   #2
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the only thing you need from it is the AIT sensor within. or ditch it completely. or explain how/why you did/would put a hot wire MAF onto your '92.
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Old 04-15-2010, 05:12 PM   #3
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If you want to use a MAF sensor (gods help you) all you have to do is run a wire (internal to the MS) from pad JP5 to any available pin on the DB37, and then externally connect from that pin to the sensor.

That wire bundle you linked to is 100% generic (you have to wire it all up yourself) so yes, it would be completely compatible, since you can wire the connector up however you want.
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Old 04-15-2010, 05:43 PM   #4
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ah my bad I was wondering if one the cables are labeled MAF on it, I guess I should email diy to find out.
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Old 04-15-2010, 05:49 PM   #5
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There aren't any wires labeled MAF in that wire bundle as the vast majority of our customers are using speed density. It's basically our 12' wiring harness, minus the MegaSquirt connector.
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Old 04-15-2010, 06:29 PM   #6
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Quote:
Originally Posted by Braineack View Post
the only thing you need from it is the AIT sensor within. or ditch it completely. or explain how/why you did/would put a hot wire MAF onto your '92.
WEll I haven't built my MS yet, but I plan to go with MSI pcb 3
Anyways just looking it over from another friend that told me to look into a MAF + MAP setup, looked over what MAF does and how it works and it peaked my interested more, So I'm looking at using a MAF setup with map sensor for baro. Gonna run a KA24 MAF from a friend I got unless I get ahold of a miata maf from the 1.8l

Currently getting the amterials for the harness, unfrountaly hard to find the 64pin connector for sale by itself(1 piece) found it but looks like I got to order 4 to get atleast one due to min order policy. If you know where a place has them with no min order and in stock would appericate that info.
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Old 04-15-2010, 06:42 PM   #7
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MAF, in a turbo application especially = Fail. It hasn't got the headroom to deal with the extra airflow accurately.

Sure, you could install a MAF sensor from something like a Mustang to get the range you need, but it's just money thrown down the toilet. Speed-density (MAP) is really the way to go here.
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Old 04-16-2010, 09:41 AM   #8
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...and put two on the mainboard and whalla, baro.
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Old 04-16-2010, 09:52 AM   #9
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Quote:
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MAF, in a turbo application especially = Fail. It hasn't got the headroom to deal with the extra airflow accurately.

Sure, you could install a MAF sensor from something like a Mustang to get the range you need, but it's just money thrown down the toilet. Speed-density (MAP) is really the way to go here.
Thats why you get a MAF for the range you will be in, if I'm running a mustang maf I'm probably putting out alot more power, the KA maf should be fine before the point where I need to build the engine for reliability reasons.
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Old 04-16-2010, 09:56 AM   #10
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But what is the point? It is just going to sap a bit of power and most likely won't run any better.

Ken
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Old 04-16-2010, 10:04 AM   #11
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i don't see anything wrong with running a maf as long as it's large enough. it's done on many other platforms with great results.
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Old 04-16-2010, 10:29 AM   #12
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But what is the point? It is just going to sap a bit of power and most likely won't run any better.

Ken
I don't see it sucking more than the current VAF does, more likely to give back power than to suck it away. now maybe there will be a 1-2hp difference between the maf and map but as long as I properly size the maf I think I should be fine.
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Old 04-16-2010, 10:32 AM   #13
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Another problem with using the MAF is that most of the maps you'll find and most of the forum's collective tuning experience is speed density.
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Old 04-16-2010, 02:09 PM   #14
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Quote:
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Another problem with using the MAF is that most of the maps you'll find and most of the forum's collective tuning experience is speed density.
truth in that, though iirc you don't need to mess with the VE map or need one, but I may be off.
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Old 04-16-2010, 02:27 PM   #15
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You need a VE map for MS-I but not MS-II. They have different MAF implementations.

Just start off with one of the MAF tables in the megasquirt docs. I would offer my "MAF" tables, but I'm using the AFM, and they're quite a bit different.

If you're going to get it dyno tuned, no big deal. But if you aren't, then you could do what I did... setup the MS for a MAP sensor, but go ahead and wire in the MAF. Then street tune it (with the MAP). After it's tuned, drive around and take logs with both sensors attached. It'll log MAP and MAF. You can then plot the data in excel (MAP vs MAF vs RPM), and deduce the proper fuel and spark tables. It'll give you a good starting point for fuel, and the spark tables will be dead on.
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Old 04-16-2010, 02:41 PM   #16
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well in that case I guess I'll shoot at getting II first since the price difference isn't to much. I had a plan of using the narrowband to tune the maf but I guess that is for MSII.

Are you using MS 1 with the MS extra firmware?
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Old 04-16-2010, 02:48 PM   #17
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Yeah I'm using MS-I/Extra. The MS-II/Extra MAF support is still a little buggy, and doesn't directly support AFM's yet. You can tune either MS-I or MS-II with a narrowband... I don't see any differences there. It'll be more difficult than using a wideband, and you'll more-or-less be guessing at your target AFRs. If you want maximum power, you either have to get a wideband or visit a dyno. But you can still see big improvements with just an NB.

FYI the code I'm using has been modified. It allows acceleration enrichment via MAFdot (among other things). The normal firmware only does AE with MAPdot or TPSdot (that is, the rate of change of MAP/TPS). If you use a MAF, you may still need to use the MAP sensor (or a real TPS) to have funcional acceleration enrichment.
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Old 04-16-2010, 04:15 PM   #18
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All that said, if you REALLY need to use a MAF on MS2, you can turn off "Multiply MAP" and then connect the MAF in place of the MAP sensor, and tune on a normal SD table. You may have to use a custom MAP curve to get things to fit well, but it should *work*.

The bug(s) in native MAF mode in ms2/extra will be fixed soon, but even after that, it will be necessary for the tuning software to support uploading new MAF curves.

Ken
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Old 04-16-2010, 08:30 PM   #19
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Won't the air density correction in the algorithm screw up the numbers if you attach the MAF to the MAP input? I could see it working with the AFM since it needs air density correction. Then again, I haven't look at the math, so I don't know....
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Old 04-17-2010, 10:18 AM   #20
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You could tune out the air density correction as well using James' feature which allows you to set the effect of the air density correction. You can just set it to 0 and off you go.

Ken
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