Finished DIYPNP for NB1, have questions about startup map.
 

I have completed the DIYPNP for NB1 miata. The alternator control circuit is built and bench tested, and I have installed an MTX-L with a wire ready to hook to the O2 input of the MS when I put it in the car. It is a stock NB with IHE.

The startup map from DIYPNP is loaded, but I have concerns because the test car (https://www.diyautotune.com/diypnp/a...0-18bp-mt.html ) is using GM IAT sensor and upgraded injectors,and I am using the stock MAF.

When I review the settings in TunerStudio, the startup map has control algorithm set to "Speed Density" and there are a host of other options set specifically for using MAP.

Can anyone confirm if this startup map, when loaded into 3.3.2 firmware will start and have the potential to run a stock car using its MAF?

I used that start up map on my 1999 but I had it setup with the map sensor and a GM iat sensor. I would run it without the maf sensor if you all ready have the iat sensor. I believe Bell engineering sells a MAF replacement tube that you could use.

Need to keep maf per class rules.

Keep in place doesn't mean actually use.

You website says it allows you to remove the MAF, not requires you to remove the MAF.

And you sell a PNP version of the ECU for my car that says it requires no additional wiring, so it stands to reason that you have a base map that works with MAF .

Do you have a base map that works with MAF or not? If not, what is the MS2PNP using such that it is:

"Fully Plug and Play Installation - No wiring required for basic functionality. Average install time is under 1 hour!"

?

I cant think of a racing class that allows you to eliminate the stock ecu (which is required for using any of the PNP MS) but would require you get keep the stock sensors.

Dont play dumb. You know that this is for a parallel install for SCCA STR, like the one Ben performed with his DIYPNP several years ago. It has the additional benefit that it can be plugged in without an external harness.

I sent a letter to the STAC for clarification and they did not further define piggyback, only that the car needed to maintain OBD2 functionality and remain plug compatible.

This is the same question you emailed me, do you think I'm going to give a different answer here?

You don't have to remove the MAF if you don't want to, but removing it adds hp. The MSPNP is set up for speed density and will not use the MAF for load calculations. If you really want to run on MAF, you can find its transfer curve and have at it.

I sent both around the same time, giving you the option to respond privately and/or publicly. You haven't responded to the email, but I would still appreciate a more detailed response on your company's position.

Posting in the forum can help to enlist the experience of others who may be able to weigh in on the problem, while the email is a business communication.

Were the MAF fixes made for the MS3 ported into the MS2?

How is it that the MSPNP uses MAP but does not require any additional wiring? According to your documentation for using MAP it requires an additional IAT sensor.

The MS2 manual states it uses MAF, your website says it is plug and play and requires no additional wiring, yet many posts on msextra.com show that bugfixes were required between 2012-2014 to get MAF working. Were those ported into MS2 codebase?

Why did you get a DIYPNP to make a parallel ECU? I would have made a whole bunch more sense to use a universal MS for this and just add the couple miata specific circuits you needed.

You need to find the transfer function for the miata MAF. If you cant find it you'll need to get the car running on MAP and then data log the data coming in from the MAF then do some magic in excel to generate the transfer function which should be close enough, then remove the vac line to the MAP and setup the ecu to run on MAF and then fine tune the transfer function you just created.

Chris, DIYAutotune hasn't lied about "PNP without additional wiring". You do need to add some tubing for the MAP, but technically, that's not wiring.

To get PNP you remove the stock ECU and plug in the MS. Without any change in wiring the MS will use the IAT built into the MAF. It won't use the MAF itself, just the IAT for speed-density. You have the option of removing the MAF and adding a separate IAT.

Parallel installation is a completely different game. It's unfortunate if you misunderstood before buying the MS, but parallel installation is not going to be PNP with no additional wiring. I'm sure that DIYAutotune never made that promise. If you thought they did then you misunderstood.

Leafy, Yes, that is the plan, but I need to know if the MAF bugfixes were ported into the MS2 to know if this is worthwhile or a fool's errand.

The MAF transfer function varies by car because each one has different plumbing or sensors, so its a given that you would need to log it. Restriction aside, MAF provides several advantages over tuning with MAP, so this is a worthwhile pursuit and I had full reason to believe it was supported by the ecu.

I have read of enough issues from the 2010-2012 timeframe in getting maf to work that I need to know if they were resolved and ported to the MS2. I know there are a handful of tuners working with MAF on the MS3.

Parallel wiring is for class compatibility. THe plan is to get it working first then develop a parallel harness using sourced oem plugs.

Thanks for describing how it uses the IAT sensor in the MAF. That makes sense and I may pursue that option.

fuck the MAF.

Yes. I'll have to get it running with map and then log the MAF voltages to create a transfer function.

Does anyone know where to source a 4mm x 4mm x 1/8" T connector for map?

The map input takes 1/8" and the manifold line is 4mm ish.

4mm and 1/8 are close enough

The air temp sensor is in the airbox, not the MAF.

Thats what I thought. Given there is a free standing stock IAT, why recommend installing the GM IAT?

If I dont install the GM IAT, does that mean it will be running in MAPMAF mode as opposed to Speed Density?

Does the startup map require the GM IAT?

That's what I ended up going with. I asked some questions of one well regarded builders on this site and specified that I absolutely needed it to be a parallel install and that I needed to use the MAF since I could add no other sensors for class legality. Their preference currently is building advanced PNP units, but they suggested a universal MS with a patch harness they'd build. We'll see if it works out when it shows up. In the future if I move away from the miata, I'll still have a badass standalone ecu.

In theory the packaging doesn't matter. The universal units rely on an external harness and the PNP units do it internally. I like the internal design - a parallel harness could be developed using the extra db15 connectors of the diypnp (assuming it doesnt require over 15 leads.)

A universal megasquirt also doesn't handle alternator control for an NB. Reverant was involved in the early development of a solution. JasonC developed an analog circuit and Reverant programmed a logic controller to do the same. Whatever solution he provides will have some miata-specific controls built in, but they can probably be disabled if used on another car.

My only concern with the MS2 is if the MAF bug fixes were ported to the MS2 codebase. There are several guys tuning with MAF and the MS3, but it was a result of code changes made in recent history. Also absolutely no startup maps for MAF and ms2.