HELP New Brain-style MS3x build first start issues!
#1
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
Having problems with my initial run after building the MS any help would be very appreciated!
I just completed a from-scratch build based off of the awesome guide at trubokitty. MS3X with the harness and connector. Car is a 94, mostly stock, just a RB type header, not boosted, 14point7 Spartan II wideband, GM IAT kit from diyautotune, that's it. I loaded the firmware from the site as recommended and had no problems. Used the 94 base map. MAP line is plumbed, IAT is installed, original airbox still there but MAF is unplugged. IAT is sitting in the airbox for now.
I calibrated the TPS, IAT, and CLT per the guide. Seemed ok. Started it and did the initial timing setup.
Wideband is wired directly to the MS. First start (and all starts) worked but car ran like crap and it will die if any throttle is given. The sensors have readings but the AFR is pegged at 19.2. This wideband goes through a sweep when given power and that shows on the dashboard in tuner studio ... it will sweep from about 12 to 16 to 19 and then stay there until the car is started (normally). The WB has been in the car for a few months now using the simulated narrow band output connected to the car's harness. On the stock ECU, the car runs fine with the simulated NB output. The gauge i have is a speedhut calibrated for the Spartan and it works fine as well. The gauge and TunerStudio dashboard always match exactly.
Basically the car starts and the RPMs are really low then it climbs to 950 then drops to an even 850. However the car is shaking a lot like it's running on too few cylinders or the firing is off or something. Any throttle causes it to stall. Tune is set for wasted spark, sequential injection. I haven't changed these from the original basemap Brain provided. No sync problems. Main thing is that the AFT is pegged at the top and doesn't change. I set the req fuel to 7.5 and although I could smell gas from the tail pipe, the AFR didn't budge. Same on the gauge which is wired directly to the WBO2 as well.
I put the stock ECU back in and plugged in the MAF and it ran normally.
What did I do wrong? Any ideas to go from here?
CurrentTune.msq
2018-06-08_14.25.29startup.msl
2018-06-08_14.21.39highspeed.csv
I just completed a from-scratch build based off of the awesome guide at trubokitty. MS3X with the harness and connector. Car is a 94, mostly stock, just a RB type header, not boosted, 14point7 Spartan II wideband, GM IAT kit from diyautotune, that's it. I loaded the firmware from the site as recommended and had no problems. Used the 94 base map. MAP line is plumbed, IAT is installed, original airbox still there but MAF is unplugged. IAT is sitting in the airbox for now.
I calibrated the TPS, IAT, and CLT per the guide. Seemed ok. Started it and did the initial timing setup.
Wideband is wired directly to the MS. First start (and all starts) worked but car ran like crap and it will die if any throttle is given. The sensors have readings but the AFR is pegged at 19.2. This wideband goes through a sweep when given power and that shows on the dashboard in tuner studio ... it will sweep from about 12 to 16 to 19 and then stay there until the car is started (normally). The WB has been in the car for a few months now using the simulated narrow band output connected to the car's harness. On the stock ECU, the car runs fine with the simulated NB output. The gauge i have is a speedhut calibrated for the Spartan and it works fine as well. The gauge and TunerStudio dashboard always match exactly.
Basically the car starts and the RPMs are really low then it climbs to 950 then drops to an even 850. However the car is shaking a lot like it's running on too few cylinders or the firing is off or something. Any throttle causes it to stall. Tune is set for wasted spark, sequential injection. I haven't changed these from the original basemap Brain provided. No sync problems. Main thing is that the AFT is pegged at the top and doesn't change. I set the req fuel to 7.5 and although I could smell gas from the tail pipe, the AFR didn't budge. Same on the gauge which is wired directly to the WBO2 as well.
I put the stock ECU back in and plugged in the MAF and it ran normally.
What did I do wrong? Any ideas to go from here?
CurrentTune.msq
2018-06-08_14.25.29startup.msl
2018-06-08_14.21.39highspeed.csv
#4
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
![](https://cimg8.ibsrv.net/gimg/www.miataturbo.net-vbulletin/741x528/crankpulse_b4920b92fe03150c5c71d4f6dafe23e6d0eb1776.png)
![](https://cimg9.ibsrv.net/gimg/www.miataturbo.net-vbulletin/434x453/cranksettings_a263afd4ed679f2ff44b97badba0e88a7470ab44.png)
Ambient is hot -- 95 or so and CLT was at operating temp I think. I checked for leaks and upstream the only option is the manifold gasket which still seems ok. I couldn't feel or smell anything. Downstream is a flange with a bit of soot, could that do it? It ran super smooth on the stock ecu. Only weirdness was the AFRs jumped around a bit at idle - avg was 14.7 but it bounced between about 14 and 15.5. I was assuming that was because of only using the narrow band on stock but maybe was a leak?
Timing is dead on and idle rpm is 850 and no hunting but it sounds like a lawn mower. The vibration is excessive.
#5
Cpt. Slow
![](/mt2011/images_td/ranks/supporter1.gif)
iTrader: (25)
Join Date: Oct 2005
Location: Oregon City, OR
Posts: 14,360
Total Cats: 1,184
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
Stock is literally the best tune in the universe. Of course it runs well. It hardly needs the o2 sensor, and it 100% correctly anticipates ignition and fuel requirements for any change in load or throttle.
Your tune does not.
Niether of those settings are the right one. It’s under startup/idle menu, cranking duty something something. Should be only a ~8 cell table.
Once you fix the low start rpm, take the whole fuel table and multiply by 1.1, see if that helps
Your tune does not.
Niether of those settings are the right one. It’s under startup/idle menu, cranking duty something something. Should be only a ~8 cell table.
Once you fix the low start rpm, take the whole fuel table and multiply by 1.1, see if that helps
#8
Cpt. Slow
![](/mt2011/images_td/ranks/supporter1.gif)
iTrader: (25)
Join Date: Oct 2005
Location: Oregon City, OR
Posts: 14,360
Total Cats: 1,184
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
That can't be right.
I might suggest trying the 1.1 multiplication. That adds 10% additional fuel, and if it gets better you know it was a fuel issue. If you're unsure, return to the previous fuel table and multiply by 1.2. If that doesn't fix it, you most likely don't have a fuel issue. But if your fuel table was off by 50%, I don't think it would start.
This is all just guessing because I think you've got a secondary problem of your wideband not working properly.
I might suggest trying the 1.1 multiplication. That adds 10% additional fuel, and if it gets better you know it was a fuel issue. If you're unsure, return to the previous fuel table and multiply by 1.2. If that doesn't fix it, you most likely don't have a fuel issue. But if your fuel table was off by 50%, I don't think it would start.
This is all just guessing because I think you've got a secondary problem of your wideband not working properly.
#10
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
The wideband definitely works. There's no change between the sensor and the gauge from before the megasquirt and after. On stock ecu it provides very valid looking values. On MS it's pegged at lean...almost like when you go into full decel vacuum and it will go to 20 for a few seconds. I've seen the same behavior on other widebands on deceleration (though I'm def not an expert). The wiring seems ok, it will match the gauge number in tuner studio exactly. I think the tune is really off for my car and it can't read anything in this state.
I checked the harness again because it really sounds like a cylinder is wrong like no fuel or spark. But every thing looks correct.
I'm about to try both suggestions and will report back. Current tune is the braineack base.
I checked the harness again because it really sounds like a cylinder is wrong like no fuel or spark. But every thing looks correct.
I'm about to try both suggestions and will report back. Current tune is the braineack base.
#15
Cpt. Slow
![](/mt2011/images_td/ranks/supporter1.gif)
iTrader: (25)
Join Date: Oct 2005
Location: Oregon City, OR
Posts: 14,360
Total Cats: 1,184
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
Injector testing is a little less intuitive than ignition testing. Go to general fittings and find out what injector channels you use, usually A, B, C, and D. Set your interval for ~100ms (1200rpm), set test mode to "one", select your first injector channel (again usually A), set pulsewidth to ~2.0, and total # of injections to ~1000. Click start, and you'll see the counter counting down. Once it reaches 0, it'll stop. But you should hear clicking at 1200 clicks per minute. If not, you've found your problem. Repeat for B, C, and D channels.
#17
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
Injector testing is a little less intuitive than ignition testing. Go to general fittings and find out what injector channels you use, usually A, B, C, and D. Set your interval for ~100ms (1200rpm), set test mode to "one", select your first injector channel (again usually A), set pulsewidth to ~2.0, and total # of injections to ~1000. Click start, and you'll see the counter counting down. Once it reaches 0, it'll stop. But you should hear clicking at 1200 clicks per minute. If not, you've found your problem. Repeat for B, C, and D channels.
So crap. The harness seems ok, checked several times now and before heat shrinking it, I tested with an ohm meter to be sure the solder joints were good.
Any thing else I can check in the tunerstudio config?
Tried batch injection just for fun and it was loads better. Idles at 950 or so and about 11 afr after on the default req fuel (11.4). Afr was reading very steady and I could rev without stalling.
#18
Cpt. Slow
![](/mt2011/images_td/ranks/supporter1.gif)
iTrader: (25)
Join Date: Oct 2005
Location: Oregon City, OR
Posts: 14,360
Total Cats: 1,184
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
Start by checking for voltage with the key on at those two injectors. They should have constant battery voltage with the key on. Second, check the signal pin for resistance/continuity from the injector plug to the MS. I'd check the wiring first, because at first glance I see nothing wrong with the sequential settings.
#19
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
Start by checking for voltage with the key on at those two injectors. They should have constant battery voltage with the key on. Second, check the signal pin for resistance/continuity from the injector plug to the MS. I'd check the wiring first, because at first glance I see nothing wrong with the sequential settings.
OK now it's the MS itself doing something wrong? I'm not sure how to probe that.
#20
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
I swapped injector plugs around and tested the physical injectors. They all fired when connecting to a working plug (B or D). Anything connected to A or C would not fire.
Also I measured the voltage for the signal wire when running the test mode and strangely it was the same as a working one. They are like 0.010 V when off and 0.035 when active. I don't have an oscope. Maybe if I slow the pulse i can see it change on the multimeter, not sure.
From what I can tell, the injector drivers are on the 3X board itself and not something I assembled. I took it apart again and inspected everything for burns or evidence of over heating or anything but didn't see anything.
Also I measured the voltage for the signal wire when running the test mode and strangely it was the same as a working one. They are like 0.010 V when off and 0.035 when active. I don't have an oscope. Maybe if I slow the pulse i can see it change on the multimeter, not sure.
From what I can tell, the injector drivers are on the 3X board itself and not something I assembled. I took it apart again and inspected everything for burns or evidence of over heating or anything but didn't see anything.