I'm thinking about doing this setup. I plan on doing an FMII Hydra setup on a '99 here in NJ. I definitely want to keep it OBDII compliant (ahem... OBDII inspection compliant )

Let's see... In order to do a swap to get through inspection I'm thinking I'll need to swap the following:
ECU
Injectors
o2 sensor(s)
MAF (put it back in somehow...)

I could pop the wastegate off in order to keep the boost to a minimum, pull the hose off of the BOV so there's no drivability issues...

Thoughts?

y8s, have you progressed any further on your parallel install?

 

does figuring out it's easier to use a second knock and coolant temp sensor mean "progressed"? because that's all I've done. ... oh ... that and highlighted a copy of the ECU harness connectors in colors corresponding to my lists above.

in theory to get through the inspection you may not need to pull anything. if you can set an output map to provide MAF data, the rest can be shared.

the stock ECU wont throw codes as long as you're providing good tuning.

 

miniature update:

I bought a GM temp sensor and pigtail for $15ish. why? because:

1. it's easier to drill and tap a known thread size I have a tap for
2. Hydra themselves said they use the DELCO (GM) setting for the miata temp sensor anyway, so at worst, I'm improving the accuracy of the system (hah)
3. no opening of ECUs.

also, I got some data from JasonC SBB on the stock AFM. TBA.

 

who doesn't like pictures?

I took jason's magic AFM equation and popped it into excel in something resembling a 3D map. and made.... a 3D graph:

Here's the raw equations up to 8k rpm and 200kPa MAP.



clearly you'll get an overvoltage on the ECU input for the AFM so ... Jason suggets capping the voltage at whatever the AFM reads at WOT in a stock vehicle.

lets assume for the sake of easy pictures, that number is 5.



Similarly, there's a minimum voltage that the ECU will want to see, so that needs to be measured too. I've got an OBDII scanner I can graph with so perhaps that's the magic bullet.

Or maybe it's "stick a voltmeter across the AFM pins"?

And here's what the 01 service manual says:

MAF Voltage:
Ignition switch ON: 0.9—2.0 V
Idle: 1.7—2.4 V (after warmup)

MAF value:
Idle: 2.2 - 3.2 g/s (warm, 750-850 rpm)
2500 rpm: 6.5 - 8.5 g/s

I suspect I can plug in the OBDII and take readings at various engine speeds and then plug in the hydra and try to put in values that the ECU interprets as the same as if it were a real AFM.

 

I've updated the excel spreadsheet to match Jerem/FM's "PWM Map 9 Scale" spreadsheet since the PWM maps do not show units or values, just percentages X or Y. I will simply match the one for VVT in terms of X and Y values and place my duty cycle values in there.

As it is now, I have created a nested IF statement that takes the first constant value of the AFM equation and makes it a variable. this allows me to set a minimum value for the first IF() so that I can match the test requirements for the AFM signal at 0 RPM, 100kPa (key on, car off) as well as the warm idle value (700-1000 rpm, 20-35 kPa).

Then the second IF() statement is based on the function compared to a max value. if it exceeds the value, it uses the set max value.

Wanna see it? Of course you do. I have created 3 variables:
coef (the constant value)
min (the minimum value)
max (the maximum value)
and I can drag the cell corner to set the 3D region matching the PWM map because of the $ in the cell location names.

oh, and I divided by 5 (volts) so it shows up as a percentage aka duty cycle of the PWM.

NEEDLESS TO SAY, it will take about fifty years to pgup and pgdn this into the hydra software...