question for people using MAP sensors

[Uncle Arthur]

All this discussion has raised a few questions for me.

Does anyone know how the functionality of the EManage unit compares to these and are there things it simply cannot do that would be required for FI on a 1.6???

[93_Clubman]

but what it has confirmed is that i am on the right track. i think i can nut something out for a lot less than $370!

quoted from miata performance handbook by norm garrett for the na6:

*pcm = ecu

"an alternative method for recreating the afm's signal is to use a map sensor commonly available from auto parts stores. in the same way a 5 volt signal can be fed into a map sensor & a decreasing voltage signal retured to the pcm. while throttle position & manifold vacuum are closely related, the map sensor scheme will give a slightly different ignition curve. the benefit of the map sensor setup is its ease of construction. since most map sensors put out 0 volts at high vacuum, you need a voltage inverter to get the signal going the right way for the *pcm."

"the miata afm runs from 4.5 volts at idle to 0.4 volts at WOT, pretty much the opposite of a map sensor"

[Boags]

Well, that makes things a sheetload more interesting... I can't imagine a voltage inverter being hard to come buy or expensive...

Thanks 93_Clubman!!

Boags

[93_Clubman]

garrett provides a circuit for one which he says can be built from parts @ radio shack for @ us$7 back in '98

[STV]

if you could post up that schematic clubman_93, i think there would be a few nerds on here willing to give a burl!

Cheers mate
STV

[93_Clubman]

if you could post up that schematic clubman_93, i think there would be a few nerds on here willing to give a burl! Cheers mateSTV

happy to, but don't have a scanner @ home, so will do @ work in a day or two

[Sean]

By the time you buy a bipes and an SAFC, you could probably afford a full programable unit.

Think brands like wolf, microtech, adaptronic, megasquirt.

[93_Clubman]

Happi, I've emailed your hotmail account a scan of the circuit - can you or someone host the pic? I've also found a little more info on a UK site which I'll include shortly.

[Boags]

93_Clubman, if you email me I can host them for you...

gmarsh@hotkey.net.au

Boags.

[93_Clubman]

many thanks Boags - just sent...

found another bit of info recently that might be of use if going from AFM to MAP - see post by tritium approx 2/3 down the page in following:

http://www.mx5ocforum.co.uk/viewtopic.p ... e9fa33c0a0

Garrett's book also points out the if you convert to MAP & remove the AFM you'll need to circumvent a safety feature of the AFM which is designed to cut fuel as soon as no air flow is detected. Circumventing this safety feature requires a jumper between pins FC & E1 in the plug connecting to the AFM (see an earlier post in this thread ref connector pin info).

[93_Clubman]

woops - see bottom of page 1 of this this thread for connector pin info:

http://www.aus-cartalk.com/viewtopic.ph ... sc&start=0

[Boags]

Here you go guys...

It is 900kb because it is a .tif file, which might be annoying on dial-up...

http://www.hotkey.net.au/~gmarsh/voltagesignalinversioncircuit3.tif

Boags