I'm having a ****-show of a time getting my track car running correctly (at all) after trimming the OEM dash and body harness 18 months ago. I made a handful of weekends last summer with varying technical issues which degraded to the point that I can't even get it to run for a minute now. The quantity of variables are now embarrassing and I'm sure I've exacerbated at least a dozen minor problems 'fixing' and troubleshooting things. I'll never get all the facts in one post and I'm sure I have some incorrect AssUme-ptions so I don't want to steer the troubleshooting the wrong direction. Here are some basics of the car:
'90 Chassis
'04MSM motor and turbo
Adaptronic 420c
Gutted NA6 body and dash harness with toggles for basic functions
Toyota COPs running wasted spark
The other blah blah blah is in the build thread in my signature if anyone cares but this will hopefully get us started...

*Disclaimer - I've forgotten a lot of details over the last many months but I will do my best with the facts...
Last season, the performance degenerated to the point where the car wouldn't run at all. The car seemed to suffer from intermittent ignition cuts while at speed at at some point, I discovered the crank trigger wheel had come loose which certainly caused some issues. I fixed that but intermittent problems persisted. It came to a head as I was loading it on the trailer to leave for MRLS at the end of September. Some of you will remember the stock MSM street car dicing it up in the A group with the fast guys in race cars. 72 hours before the driver's meeting, I didn't have much choice! Needless to say, I'd like to bring the right car this year not to mention 6 or 8 HPDE runs I was hoping to make this summer. I suspected a dead ECU and since so much of the harness was set up for the 420c (yes, I know I will probably end up needing something better), I sourced a used unit.

The new ECU started and ran which was a big improvement but it was still cutting out intermittently so I then suspected the adapter harness. Adaptronic doesn't support the 420c anymore so I bought a generic NBB adapter and soldered it to the early NB harness that came with the replacement ECU. The car started right up and then suffered from the 'sudden' shut down issue it had with the other combinations. At that point, I started trading out parts I had as spares anyway - different coils, different injectors, Cam and Crank sensors. I put in new plugs - the old ones were pretty black but uniform, For a while it would run (poorly) if I kept my foot on the throttle so I traded out the IACV. Water, MAT, MAP and TPS all pass sanity checks on the laptop so I didn't change any of them. Compression was checked and is fine.

As I type this, the car will barely fire. Different combinations of adapter harness and ECU have worked enough to start and idle the car so I'm hoping that there aren't two dead ECUs in the garage. If there are, something about the car is killing them, Today, I'm going wire by wire through both harnesses (the original Adaptronic piggyback harness and the one I built this winter) checking for continuity. Once that is confirmed, I'm continuing to the engine harness checking the same circuit (this is easier since I have just looked up the wire in the Adaptronic schematic and cross referenced it to the Mazda diagram and probed the pin on the mazda side). It is slow going but so far everything appears to be fine until I got to the coils...

Toyota COP Question:
I am running a basic Toyota COP ignition wired according to Brain's writeup here. https://www.miataturbo.net/useful-sa...writeup-12704/, I was probing the trigger for one of the pairs when the probe touched the cam cover and the meter beeped. I figured something must have grounded out at the other end but the trigger was definitely continuous to ground. When I unplugged one of the two coils, the circuit was interrupted. I thought I might have found the issue but further checking shows that the same is true for the other coil on the 1-4 side and the same results happen on the 2-3 trigger wire with those coils. Two coils gives trigger to ground. One coil does not. The results are the same with spare coils in and out of the head,

I tried searching for that phenomenon but found nothing. That's when I decided to swallow my pride and say f*ck it - I'll post about the problem and see if some of the brighter minds can help. Yes, I know I almost certainly caused this by gutting the NA6 harness that was running most of the non-engine system previously. Yes, I know nobody runs a 420c anymore. Yes, I know I should start over with a new engine harness and a Megasquirt. I may do that, but I'd like to save the $1,000+ it would cost for parts and a new tune. As it is, I'm 'saving' $500/day on registration and consumables not driving so I guess I can afford it. If something is cooking ECUs, I want to fix it before I put another victim into the mix. Like I said initially, I'm sure there are details missing so let me know if you have any ideas or questions. Thanks!

 

Still baffled. I did find that the replacement harness had the injectors firing backwards. 1 to 4, 2 to 3, etc. The colors were right according to the diagram but they were in the wrong position on the terminal. That helped it misfire a little more aggressively but not enough for further troubleshooting. I've gone through nearly every wire on the engine harness and verified all the various wires in the cab. The sensors all pass sanity checks and the connections at the 4 most critical points are fine (injector, coil, Cam and Crank sensors) have been triple verified. Even so, the harness has been through hell troubleshooting and is hacked to **** so I ordered a clean used one off fleabay. I'm now officially shopping for a completely different ECU. Waving the white flag...

 

I didn't want to suggest it, but that's exactly what I would be doing at this point. Remove every wire, replace, replace ECU with new Megasquirt.

 

Good job Brian. Ditch that shitty ecu!

I don't know what kind of testing modes are available for the adaptronic, but with MegaSquirt you can test coils, injectors, fan, tps, etc, and then finally check sync of cam and crank signal. Proper diagnosis will save you a lot of wasted time. Stay on the forums, lots of help here.

 

I sent Nick a PM about the AEM his has for sale. I never minded the Adaptronic until it stopped working. Now I mind it a lot...

 

Test modes? The extent of that is turn on the laptop and see what the sensors say. I have zero confidence that the ECU isn't the problem.

 

No AEM!! Hydra or MS.

 

Reasoning?

 

OK Megasquirters - looking a DIYAutoTune's site I'm confused about some things. It looks like I can do one of the following:

1. $1,199 for the PNPPro for the Mazdaspeed https://www.diyautotune.com/product/...daspeed-miata/. This is a track car so it doesn't need to idle in traffic with the AC on and I don't use a bunch of the wires in the harness anyway. It would also be more of a PITA to do sequential ignition since the harness doesn't have wires for it. This does more than I need it to right?

2. $659 plus two harnesses for another $105 gets me the MSIII with MS3 Expansion https://www.diyautotune.com/product/...-57-assembled/. This does more than I need it to also?

3. $559 plus a single $50 harness gets me the MSIII without the MS3 Expansion https://www.diyautotune.com/product/...-w-black-case/. Does this skip features someone would want on a track car? I honestly don't see myself caring about flex fuel. The only fancy feature I really want is the SD card for datalogging. It doesn't need to be complicated.

What is the difference between option 2 and 3? Is there a 4th option I'm missing? Unless I'm missing something, I need:

Four Injectors
Four Coils
Water Temp
IAT
Cam
Crank
TPS
IACV
Knock
MAP (built in with any of the MS3 options)
Wideband input (LC1 installed already)

I use an NA8 alternator and manual boost control. I left the NA6 circuit in place to run the fan. Oil Pressure, Oil and Water Temp, are on the dash. ABS is standalone. I don't care about launch or traction control. I use horsepower to to mask bad driving - I don't need a computer making me even faster. What do I want? Feed me with 'da spoon!

 

Option 2 and 3 are both build your own ECU kits. The ms3x includes all of the circuits necessary to use the ms3x circuits.

Don't do number 3 unless you enjoy pain and suffering.

 

Who's gonna tune it?

 

The website lists both options 2 and 3 as 'Assembled'. You can save a few hundred off either buying the kit. If that's wrong, their website is horribly misleading. Obviously, there would be a bunch of wires to terminate but that is preferable to me than the street car's plug-n-play that would need wiring anyway. What are the MS3x circuits and why should I want them?

Martin - I normally get tuned a KO but Kris doesn't like MS. I'd like to find someone in Seattle so I can avoid the full day round trip to Oregon. I could pay more for a Hydra to please Kris but the way Hydra charge for upgrades and features always rubbed me the wrong way. Great for the wine and cheese crowd with clean hands but my wine has a screw top and my cheese comes in a jar...

 

I've heard mumblings about Hydra going out of business. I would steer away from them. Ms3 will do everything you need on a track car and more.

Did not realize you could buy them assembled for that cheap. You would still need to build the patch harness and stuff.

 

Soldering dozens of tiny wires is kind of soothing. [/mentalillness]

 

For a track car do I need the expansion for $150 more including the expanded harness?

 

Yes. The expansion has all the circuits you would have to build if you were just using the base one. Without the expansion board you would be having to build circuits and **** around. With the expansion board just build your harness and start it up.

 

Perfect! Thanks for clarifying.

 

OK, sorry for all the hand-holding but this crap is confusing. If I buy the assembled MSIII MS3X Expanded listed here https://www.diyautotune.com/product/...ed/#ywtm_78234 do I need to buy an additional knock control module to hook up my OEM knock sensor? I can't imagine something that looks to be 'everything you need' would require additional hardware wizardry.

 

Yes. You need the knock module.

The mspnppro is the "everything you need". Its based on the ms3pro which is basically an enhanced version of the ms3.

 

You have a 4th option. PM Braineack and he will set you up with a PNP built MS3X with the wiring harness for $800, then it will be $90 extra or whatever the additional cost for the knock module is.