MSPNPPro-MSM0405 Sensor Inputs
 

I just got an MSPNPPro-MSM0405 for my 04 MSM. I have two questions (this second) regarding how to connect sensors. I have the GM IAT sensor and an Innovate WB sensor. I have zero experience with MS and/or TunerStudio, but I am (marginally) trainable.

WBO2 sensor: Is it better to connect this to one of the OEM O2 sensor circuits or use one of the available Option connector pins? Does the base configuration file have the WB02 sensor set up for a particular input?

IAT sensor: I believe the IAT sensor would replace the IAT2 sensor on the MSM, correct? I see other threads mention connecting to the IAT to the MAF sensor circuit. It would seem more straight forward to connect to the IAT2 circuit. Or should one of the Options connector pins be used. Again, does the base configuration file have the sensor connected to a particular pin.

Thanks,

I cannot recall but believe the factory front o2 signal coming into the ECU was where my wideband signal entered the megasquirt. I believe the megasquirt will be looking for the IAT on the MAF circuit because of the way it is wired/soldered up. Mazdaspeeds are sometimes different than the rest, so take everything I've said with a grain of salt.

I just wanted to say hello because you were a new track guy. You should post up in the "Meet and Greet" section and give us some pics and details about your setup and what you have been doing with the car(s).

Any of them will work.

The base configuration is set up for the stock narrow band.

The Mazdaspeed MSPNP is set for IAT2 by default. You do not need to swap this for a GM sensor, but if you wish to do this, wire it to the IAT2 connector. While the NA and NB1 Miatas have the IAT sensor in the MAF and you can wire a GM IAT to the MAF connector, the NB2 had a separate MAF and IAT sensor, so you wouldn't wire the IAT to the MAF connector.

I was wondering about those stock NB2 AITs, is there an accurate thermistor table for them so no wiring is required?

We're using the values from the MSM's workshop manual.

Thanks for the replies. I'm not into doing more than necessary, so I'll continue to use the oem IAT2 sensor. I did already make arrangements to weld the bungs for the GM sensor and the WBO2 sensor so that will be done in case I find some need for the GM sensor.

Ben and/or Matt, just so I'm clear, the base configuration is using the front O2 sensor, right?

On a very positive note, it did start and idle tonight. I'll do the timing check tomorrow and finish connecting the WBO2.

Thanks again!

Right, it's normally configured for the front O2. There's a pull off jumper inside to switch to the rear if desired.

So a gm ait is not even needed with an MSM? Cool
Guess I'll be selling mine then

With the wb02 into the oem nb02 wiring - wouldn't resistance be different and require a custom calibration? I heard most units are set up for specific wiring length and should never be cut or lengthened...oem wiring harness is quite a bit of "lengthening"

Matt, I don't find a place in TunerStudio to change the curve for the O2 sensor. Can you point me in the right direction?

Edit: Never mind. Found it.

Thanks,

1. I ended up using the GM sensor. I found that AIT2 using the OE sensor was not correct. It was reading around -20F. My garage was cold, but not that cold. I tried the other Mazda calibrations and none came close. The sensor checked out OK. So I think I could have made it work. I had a limited window to deliver the car to the dyno shop, so I connected the GM sensor to the existing IAT2 harness. It provided a believable temperature of about 60F when the GM sensor was selected from the pull-down menu. I'll confirm it next week.

2. The length of the output signal wire on the WBO2 sensor controller should not matter. It is a 0-5V output and should be relatively immune to noise and wire resistance. The length of the wires between the WB controller and the sensor may matter. I wouldn't mess with them unless absolutely necessary.

I cut the OE front O2 sensor wire at the ECU and spliced in the WBO2 signal wire. The readings from MS match the gauge.

YMMV

I had the same issue with the IAT sensor and after trying to manually calibrate once the standard settings didn't work I change out to a GM. I have the FM intake kit and found that the bung for the factory IAT can be drilled out to the NPT theads needed and tapped. I then made a brass adapter that will allow me to put the stock one back in place for when I need the stock ECU to go through emissions. I ran my wideband into the external connector, again so I can put the stock ECU in place with minimal fuss.

DIYAutotune?

Can you please look into this? It appears that everyone is having this issue, so there appears to be a problem.

It could just be that the GM sensor is a superior sensor for the MS, which is why they haven't spent a lot of time getting the calibration perfect. My guess is they're making a best-fit linear calibration for a sensor that doesn't operate in a linear fashion.

Based on my experience while getting the calibration values, the stock sensor is so slow to respond it's pretty much useless for tuning anyways.

I have the DYI MS3 Pro and LC-2 wideband.

I'm going to do my install in two weeks.

What is the part number for the GM IAT sensor?

Thanks
J

We used the calibration values from Mazda's workshop manual. They appear to be wrong.

I purchased an MSM air temp sensor for verification. I will have new values soon.

WIN

:party:

Great! I'm not installing all this for two weeks, I can use the stock one then.

These values were obtained by subjecting a MSM intake air temp sensor to various conditions and measuring its resistance. I no longer have a MSM at the shop, so would appreciate if someone could try this calibration on their car:

24°F
7800 ohms

72°F
2110 ohms

190°F
396 ohms

so basically the same values mazda always uses.

No, I plotted them out and what I measured is different at low temperatures.

I realize you did that, numbers just seem close to Mazda clt values.

We are talking about the air temp sensor that is threaded in near the throttle body correct? My stock one in the car measures 42.8k at 62 degrees f which is what my garage is currently sitting at. I took several measurements and put it in but wasn't sure where to set the bias resistor at. I played with the bias value until the values were not completely out of whack but found that the slow response was not desirable.

when you say slow, how slow are we talkin?

cause it doesn't need to react like a wideband or something.

the only time it needs to go up fast is during a boosted pull when temps climb, and even then they usually go up pretty slow.

and It's good enough for the oem ecu, so I'm sure it should still be useable on the MS

These appear to be the values for the first AIT sensor (airbox) in the MSM. The service manual lists:
68F - 2.21-2.69k
176F - 0.29-0.354k

These appear to be the values for the AIT2 sensor in the MSM (just upstream of the throttle body) This is the one for which we need the correct curve. The service manual lists the following for AIT2:
-4F - 357k
32F - 112k
68F - 41k
77F - 33k
104F - 17k
140F - 8k
185F - 3.5k

Mine appeared to match these values reasonably well.

I will double check with the person who measured the sensor for me.

The values entered to our base tune came straight from the service manual.

Ben, would you please post a photo of the sensor you checked?

I purchased a MSM IAT #2 (from the throttle pipe), and handed it to one of my guys to test. I don't have a picture; it's probably on his desk at the office. I'm at home. I was about to say I take a day off here and there, but I've put in about 8 hours or so today.

So... Good ol Phil thought the IAT#2 was a coolant temp sensor, and gave me values for IAT#1.

Here are correct values for IAT#2 calibration
8°F 199k
72°F 35.6k
180°F 3.8k

These values correspond to data posted by Elmos hers (which DOES NOT correspond to Alldata!)

Sorry for the confusion, folks. Should be all fixed now.

So I am thinking of buying one of these. How well does it run with the stock base map? Is it a conservative enough map for it to be safely drivable without a custom tune?

sorry, I posted this in the wrong place. Mods please feel free to move this.

Ben,
what is the bias resistor value?

*EDIT: Called DIY and spoke w/ Matt, who pointed me to megasquirtpnp.com, I had no idea about that page.

On it I found the values, and after using the "GM" drop down which gives you a bias resistor value of 249something (I forget the specific number) populated the values in, seems to be working now :)

In case anyone needs them:
temp in F-ohms
8-199000
72-35600
180-3800

All MSPNPs to date use 2490 ohm resistors as bias resistors, which is the default setting.