2manyhobyz

iTrader: (4)

Looking at building my own intake manifold this winter, but was looking for people who are currently running a 65-70mm throttle body with their MegaSquirt. I'm sure some are controlled easier/better than others.
Thanks,
-JB

richyvrlimited

iTrader: (1)

TB's are controlled by your foot?!? MegaSquirt can't, (and will not ever), do fly by wire.

If you mean the TPS attached to the TB, it's just a variable resistor, literally any will work.

hustler

iTrader: (6)

My throttle is controlled by a hand-crank.

MD323

not true, the 3 wire mazda one is NOT compatible with MS as its just an on/off switch

Braineack

iTrader: (62)

While it's more than just an on/off switch, you are correct in it's incapatiablity.

But we all know we are talking linear TPSs here.

shuiend

iTrader: (24)

I think he wants to know which throttle body is 65-70mm and has a TPS that will work with a megasquirt. I know my ford throttle body and TPS works and was easy to wire up.

Braineack

iTrader: (62)

the biggest worry if finding one with linkage that will work.

2manyhobyz

iTrader: (4)

Yeah, that's where I was going with this. Not just the throttle position sensor, but Idle Air Control etc. Shuiend, what year/car TB did you choose for your set up. And why, easier from a fabrication stand point or from a controling everything from Meagsquirt standpoint. Did the one you chose work correctly for warm up? (Chicago's gettin kinda chilly now)
I'm goin to the junk yard this weekend and wanted to start looking around for options.
Thanks

Braineack

iTrader: (62)

I'd look at hondas.

Joe Perez

iTrader: (8)

The 3 wire Mazda (actually Mitsubishi) unit shipped in the '90-'93 Miatas with manual transmissions is not highly useful with the MS, as it's just a SPDT (on/off/on) switch. (It can still be used to gate the idle code on and off if you wire it right.)

The 3 wire unit shipped in all '99-'05 Miatas is perfectly usable, as it is a potentiometer.


When I did my MS build for the '92, I used a TPS from a B-series Honda engine. Of course, I kept the stock throttle body from the Mazda engine, so it was not even remotely plug-n-play. I had to cut down the shaft on my throttle body and machine an adapter ring on the lathe to mate the two. Not really relevant to this thread...

But essentially, any throttle body will work so long as the TPS is a potentiometer style unit, of which the vast majority of TPSes shipped in the last 20 years are.

Braineack

iTrader: (62)

he's talking about TB, TPS, and idle valve.

So I say again, I'd look at hondas.

2manyhobyz

iTrader: (4)

Thanks that's good news about the potentiometer idea is manufactured for most cars. Is there a key feature for idle valves that will work better or easier to control for the MS. Scott, you mentioned Hondas, is their idle valve design more compatible? Or is there more of a 2 or 3 wire design and that's what you look for? On a lot of european designs, the idle valve is a separate piece and maybe that would be an advantage.

Joe Perez

iTrader: (8)

Ignoring the old on/off bypass valves which have been obsolete for many years, most idle valves fall into two categories. Those with 2 (sometimes 3) wires tend to be of a PWM (pulse-width modulated) solenoid design, wherein the ECU switches the valve on and off rapidly much like a fuel injector. Those with more wires (typically 5) are generally of a stepper-motor design, wherein the ECU drives the valve to a specific position by literally turning a motor in the same way that the carriage on a dot-matrix printer or the head stack on a floppy drive is operated. The Miata (all years) uses a 2 wire PWM design.

The MS1 can easily drive PWM solenoid valves, but cannot drive stepper-motor valves. The MS2/3 can drive either, though driving a stepper-motor valve with the MS2 consumes a couple of pins which could otherwise be used as general-purpose outputs.

Reverant

iTrader: (10)

2manyhobyz, stick with the stock TB - your MS can only drive the stock idle valve (at 500Hz) and the expansion card (which uses the TPS to cut off the A/C) is also programmed for the stock TB.

2manyhobyz

iTrader: (4)

Allrriigghhttyy then, I guess for me I'm not goin down this road any farther.
Thanks Rev.
Thanks Joe for explaining the PWM and what people can look for in their junk yard travels.
Now, if I can find that place that bores out throttle bodies...............