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-   -   Ugh, no IAT and someone is coming to help tune.. (https://www.miataturbo.net/megasquirt-18/ugh-no-iat-someone-coming-help-tune-25070/)

rotaryjunky 08-19-2008 09:08 PM

Ugh, no IAT and someone is coming to help tune..
 
Ok, I've had this "NeoBrainSquirt" piggyback ecu waiting to go in since January. I have so little time right now and my first attempt (I am dumb) ended in a burnt ignitor, so I waited until after my big track weekend (didn't want to take any chances, car was still awesome with fmu) to try again.

I loaded it with the mspnp basemap, changed the injectors to 460cc, and fired it up. Cold start cranking was not impressive but after it fired, it ran well. But I am not getting any readings for Manifold intake temperature!? I checked all of the connections and my IAT has resistance, but nothing. It worked the last time I hooked MS up, so I am not sure what is different.

Any ideas?

rotaryjunky 08-19-2008 09:26 PM

Oh, I am using ms extra 029V. Haven't moved on to hi-res 10g yet. Baby steps.

paul 08-19-2008 09:32 PM

So it worked before and you haven't reflashed the firmware and now it doesn't work?

Is the IAT sensor hooked up directly to the MS or through the AFM harness?

rotaryjunky 08-19-2008 09:50 PM

afm harness.

paul 08-19-2008 09:52 PM

you sure you used the correct 2 pins?

rotaryjunky 08-19-2008 10:01 PM

Yeah, double checked. Switched them around and pushed on them while I watched the MS gauges. It should start working immediately in MS if it connects, right?

paul 08-19-2008 10:04 PM

i believe so.

paul 08-19-2008 10:04 PM

what happens if the inc files are deleted from the working directory? anyone?

rotaryjunky 08-19-2008 10:08 PM

Off topic but bugging me because I can't remember, what are the three lights for?

rotaryjunky 08-19-2008 10:13 PM

I also plugged in my old bipes (except CAS wires, of course), set it to air temp, and while it gave a reading, it didn't change when I unplugged the IAT from the AFM harness. I know, not helpful.

paul 08-19-2008 10:18 PM

i believe 2 are for the ignition circuits to tell you they are working and the 3rd is warm-up mode.

turbobluemiata 08-19-2008 10:36 PM


Originally Posted by paul (Post 298511)
i believe 2 are for the ignition circuits to tell you they are working and the 3rd is warm-up mode.


yea thats right...

patsmx5 08-19-2008 10:53 PM

Measure the voltage on the two wires that go to the sensor. One is ground, one goes to MS. I accidentally wired mine up and was sending +5V to the sensor instead of ground. It didn't work...

rotaryjunky 08-19-2008 11:47 PM


Originally Posted by patsmx5 (Post 298523)
Measure the voltage on the two wires that go to the sensor. One is ground, one goes to MS. I accidentally wired mine up and was sending +5V to the sensor instead of ground. It didn't work...

So one connector on the AFM harness should be 5v and the other should be a ground?

The guy that was coming over has to drive two states away tonight to work on some car. Gives me another day.

Braineack 08-20-2008 09:25 AM

The sensor simply gets a ground and then the other back to the MS harness.

I would check the continuity between the afm harness and the MS input (orange wire)

rotaryjunky 08-21-2008 12:27 AM

The AFM plug shows 5V across them. If the harness connection was bad, wouldn't I have gotten a CEL before MS? Which plug on the AFM corresponds to the orange wire on the MS?

Also, is there Accel enrichment numbers for 460cc 1.6 anywhere I can start with?

Sorry but I really want to understand how this is setup so I can do it right. Being stupid just makes it take so dang long.

paul 08-21-2008 08:14 AM

you're worried about accel enrichments when you have not IAT reading? that will affect your fueling more.

Just run new wiring from the MS to the IAT sensor. It's one wire. The other pin on the sensor goes to ground. Might as well rule out factory wiring. That will require you to reflash your easytherm values to a standalone resistor bias value or 2490 on the IAT.

jwx 08-21-2008 08:46 AM

Have you checked to see if the MS is seeing anything? I would check continuity from the MS DB37 out to the MAF plug. After that, check and make sure that they have R4 installed. You're running standalone, right?

Braineack 08-21-2008 08:48 AM

no piggyback. R4 is installed. I'm pretty sure it was working for him prior.

rotaryjunky 08-21-2008 08:56 AM

Accel not related, don't worry. I could scale them for my 460s, but I don't want to screw that up too.

So the factory ECU outputs the 5V and gets its reading based on the current draw?


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