1.8 afm on a 1.6
 

hi everyone i want rid of the masive 1.6 mechanical air flow meter and replace it with a 1.8 item can this be done as the 1.6 has a couple more wires than the 1.8 at the minute im only using the hks piggy back ecu any help would be great
thansk malc

Sell your HKS piggy, buy an MSPNP and delete the MAF altogether. If you want to upgrade, just switch to an Rx7 MAF.

does the rx7 item just plug into mine

yes it does to use the 1.8 item you need to invert the voltage signal buy a rx afm and be done with it.

which rx7 is it from is it the twin turbo

could someone be as kind as to post a pic up please

sure here it is http://www.miata.net/solo/airflowmtr.html the original faq on this stuff. He is abit optimistic on the gains but it does have all the info. :D

ok, now that the retards have had their say...
the 1.6 miata runs an AFM, the 1.8 miata runs a MAF. COMPLETELY different items that are not interchangable without extensive electrical knowledge and work.

put your afm back on the car and be done.

Uh ben ^

yeah, you act like i can read what you write.

:bowrofl:

think everyone has got quite confused y i want to put a different air flow meter on my car the only reason is i think the standard unit looks shit i have a 1.8 maf sensor and am a mechanic so wiring it up isn't that much of a task aslong as it is possible the rx7 unit doesn't look much diffrent and doesn't save a great deal of room

Yeah, Ben, it's simple. Just buy a circuit board, an inexpensive RISC processor and a make sure it's got a couple of DACs, program it with Python/C++/your favorite language to convert the 0-5V signal to the inverted 0-4.5V signal the 1.6L ECU expects.

While you're at it, might as well write code for the RISC to handle EBC and ignition timing. Heck, if you find some drivers strong enough and make an aluminum case for the board that doubles as a heat-sink, you could drive your fuel injectors off off another proc. It wouldn't take that much time...

Richard, I'm surprised you haven't done this already...it's really a no-brainer.

Well if you want to wire it up and invert the voltage then go for it. It should work just fine. My Miata performance handbook has diagrams on doing this it seems pretty simple.

And Ben i forgot you have me on Ignore don't you :p
Brian i wish i could do something that simple it might have been better than the aluminum case i have sitting by my stock ecu oh wait that is MS

Unfortunately, it's not as simple as you think, Richard :(

BTW, here's an interesting page I ran across: http://howto.globalvicinity.com/gv_w...=120&co=1&vi=1

That is exactly what i meant and i think what this guy is looking for. You don't post alot anymore brian but when you do it is very effective.

any chance you can post up the wiring daigrams and items i need other than the maf sensor and the plug and wire so i can get it sorted

will you all stop digging at each other i only want to know how to do sumat not who doesn't like who

dude, seriously
if you have to ask, it's well out of your league. don't feel bad about that; I think there's only 1 or 2 people here who could make it happen.

but the fact that you're a mechanic and can't tell the difference between an AFM and a hotwire MAF is pretty fuckin scarry.

look matey sum how i doubt it is out my leauge i do everything from mot's n service to ecu mapping i know wat im doing and if i put my mind to it could figure it out myself just thought that someone on here would of already had the same idea and of done the hard work so to speak

thanks for the help ill put a how too up in a couple of days to prove a point

If i had a scanner i would scan the pic of the circiut baord they show in the book. But you will need 4.5 volts at WOT and .4 at idle. As far as i can tell there is no C+ mapping or code required this is a simple inversion of the voltage signal. I look forward to a how to though it should be interesting. This has also been used to run a map sensor in place of the AFM but that would prove abit harder.

Well, as I said, do you know how to spec out a microprocessor with the right features (digital-to-anolog and vice versa controllers), have it mounted to a circuit board, spec out some EEPROM chips to hold the code you're about to write, a development kit that includes some sort of sync cable to attach to the port you spec'd on your circuit board so you can transfer code and bench-test the board, write and compile code to tie it all together?

If so, then you'd more than likely not have even asked for wiring diagrams. That's the least of your worries. Ever seen a circuit board schematic?

This guy makes magna look like Shakespeare.

Yeah i suck less :rofl: :hahano:

my question is.: what HKS piggy are you speaking of? the VPC? Then it should be running off a MAP sensor and AIT sensor and the AFM isn't even a requirement anymore.

I wish you the very best of luck and hope you come back and prove me wrong.

But let's be realistic. Unless you're a mechnic/EE/CE, you don't have a snowball's chance in hell. So more likely, we'll just never hear from you again.

you clearly think you know what you are talking about but you know naff all get a life i was asking for ideas and posotive input on the matter not a load of abuse about mirco processors and chips


for those of you who were trying to point me in the right direction (magnamx5) im very greatfull i will post up how to do it ina couple of days

malc

we'll be waiting patiently.

:jerkit:



I also want to reminder you that a maroon username = moderator.

are you sure it's a linear inversion? has anyone done the testing to verify this?

As far as i can tell it is the afm is just a potentiometer. i have never built or considered the circiut but from what i can see in the diagram and explanation it seems that is it linear. And the RX7 info posted earlier by brian states the same. http://howto.globalvicinity.com/gv_w...=120&co=1&vi=1

:rofl:

and that is for an rx-7 AFM vs a ford MAF. are you referring to this image? the one with the caption, "The very nonlinear AFM vs. MAF plot."?

http://www.globalvicinity.com/images....2489_4690.jpg

the relationship for a 1.6 AFM and a 1.8 MAF would, i imagine, be different from the rx-7 vs ford relationship...

Dude, have you been listening/reading this thread or the link I posted at all? Crack open a Miata/RX-7 shop manual if you'd like to read more on the AFMs they use.

No, the relationship is exactly the same. The RX-7 and Miata AFMs are basically the same, volume-measuring flow meter that read from 4.5-0V, from min to max airflow. The Ford and Miata MAF are basically the same, mass-measuring flow meter that output from 0-5V from min to max airflow.

So, you're pretty much looking at the same, inverse relationship. The numbers obviously won't be exactly the same as the RX-7 vs. Ford, but the procedure for arriving at the end result is identical.

posting to subscribe 2 this thread i hateed look of the trap door 'AFM' too so ugly and out of place i have always loved look of the 94+ MAFs!! damn i wish ne1 thought of doing this swap before i did standalone that have saved me soooo much money but i'm no mechanic and dont no ecu maping so even if i did think of it i couldnt figure it out damn shit fucker

let me no how it does

HKS FTW!!!!

Where's Lazzer when we need him... :cool:

Yes, one difference between the MAF and the AFM is that the airflow-voltage curves are inverted. And that could be solved with a single op-amp.

However if you invert one of them and then plot the curves of the two devices on a flowbench, you'll find that they are not the equal. My observations of the 1.6 AFM indicate that it is non-linear, and I'd imagine that the 1.8 MAF has some surprises as well.

That page describing the conversion was pretty, but bordering on useless. The author simply glosses over some key subjects like "The easiest way to do this is to fix the intake air temperature and atmospheric pressure sensors at constant values of our choosing" and "After constructing the translation circuit..." without actually describing the circuits involved. It's obvious that they have constructed a working version of the circuit as they have the logs to prove it, but without providing a schematic the whole thing is academic.

I guess what it comes down to is this- why bother transplanting a 1.8 MAF onto a 1.6 car when you can simply remove the air metering device altogether. Both Megasquirt and EMU have the ability to do this, and the exact steps necessary have been fully documented in detail for both systems.

Geezus! can you please use some punctuations? I understand you may be writing from the other side of the pond, but still! Last I checked, Brits used commas and periods.

(or better yet, just stop replying to this thread)

the procedure for arriving at the end result is certainly identical. as you stated the voltage relationship may be similar, but one still has to go through mapping the signals in order to find that relationship.

my argument is that this relationship is not a simple linear inversion. whoever decides they want to go through the trouble cannot just 'flip' the MAF voltage output to simulate the AFM voltage. The voltage needs to be fed through a nonlinear equation or look-up table.

after that is done, said (crazy) person has to fix the voltages for IAT and pressure in order to maintain the validity of the mapping.

in the end, i agree with others that going this route is pretty pointless. if the OP finds the afm ugly, then i personally think he should simply convert to MS and run a MAP based system.

Precisely.