Who can tell me what I fried?
05-17-2015, 10:10 PM
#2
SADFab Destructive Testing Engineer
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Going to search for the MS3 pro schematics but I'm not sure if they are released. If DIY can tell you the component I can replace that for you
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05-18-2015, 09:08 AM
#6
Cpt. Slow
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I've already sent an email to DIY, hopefully they'll be able to shed some more insight into, I'm just really curious to know what that is.
Car is a fully race prepped '93, with an '03 VVT engine, chassis harness, charge harness, and ecu harness. We're even using an '05 MSM switchblade key and ignition. We successfully completed a dozen or so drives to and from the dyno, alignment, and my house to prep it for a track day we did last month, where it sailed through 9 sessions with only a few loose bolts we missed during the build.
The night before the MS fried, we installed the mandatory kill switch. We followed these directions:
Only thing we added was a resistor to ground from the starter side of the switch, which was recommended from the switch manufacturer when installed in any car with an alternator. We tested the switch 3-4 times, once it was only a battery cut off switch, so it still ran off the alternator. Then we wired the alternator to the wrong side of the switch and it still ran when turned off. Then we had two successful tests of the switch, and called it a night.
We turned the ignition off, but left the kill switch on, which I think was a mistake.
The next morning I get a call saying the car won't start, dead battery. Won't take a jump/charge. It's a huge heavy battery anyways, so he goes and buys a new, lighter battery. It's cranking, but not sparking. Flooded. They remove plugs, crank it more to clear the engine (ignoring my flood clear instructions), and it still won't start. They diagnosis no spark. That's when I come over and hook up my laptop to test the coil outputs. As I'm waiting for it to connect, which it wasn't, I notice immediately that the fuel pump is staying on constantly, along with the fan (car hasn't ran in 12 hours remember), and 1-2 minutes later I smell a horrible burning smell and see the smoke coming out the MS box. I pull the plugs out of the back, take it out and apart, and took the photo above.
Car is a fully race prepped '93, with an '03 VVT engine, chassis harness, charge harness, and ecu harness. We're even using an '05 MSM switchblade key and ignition. We successfully completed a dozen or so drives to and from the dyno, alignment, and my house to prep it for a track day we did last month, where it sailed through 9 sessions with only a few loose bolts we missed during the build.
The night before the MS fried, we installed the mandatory kill switch. We followed these directions:
Only thing we added was a resistor to ground from the starter side of the switch, which was recommended from the switch manufacturer when installed in any car with an alternator. We tested the switch 3-4 times, once it was only a battery cut off switch, so it still ran off the alternator. Then we wired the alternator to the wrong side of the switch and it still ran when turned off. Then we had two successful tests of the switch, and called it a night.
We turned the ignition off, but left the kill switch on, which I think was a mistake.
The next morning I get a call saying the car won't start, dead battery. Won't take a jump/charge. It's a huge heavy battery anyways, so he goes and buys a new, lighter battery. It's cranking, but not sparking. Flooded. They remove plugs, crank it more to clear the engine (ignoring my flood clear instructions), and it still won't start. They diagnosis no spark. That's when I come over and hook up my laptop to test the coil outputs. As I'm waiting for it to connect, which it wasn't, I notice immediately that the fuel pump is staying on constantly, along with the fan (car hasn't ran in 12 hours remember), and 1-2 minutes later I smell a horrible burning smell and see the smoke coming out the MS box. I pull the plugs out of the back, take it out and apart, and took the photo above.
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05-18-2015, 09:37 AM
#10
There is really two problems with this. One you are bypassing your 80A (I am assuming main) fuse. Second, your alt-> battery is no longer fused. that is not a big issue, but generally I would say its a good idea to keep that fused. Especially since it doesn't need to be changed for a kill switch...
You may have other issues, but miata kill switches have been covered to DEATH by spec miata. They have both a negative killswitch and a positive one. take your pick and follow it.
Due to our setup, I generally don't think you need the 6 post expensive kill switches, you can usually move the battery over to the alternator side of the kill switch and it serves as the dump to ground should the alternator have a lot of excess charge when you kill it. This depends on which side (positive/negative) that you put the kill switch. let me dig up a few references.
Edit:
here is Dave's original instructions and someone pointing out the errant wire to IGN:
http://forum.specmiata.com/cgi-bin/u...1;t=002603;p=0
(the thread talks about the negative side kill switch, which is a 4-post setup on the battery negative and alt control signal from the ECU).
Still not sure how this fries your MS3 though...
You may have other issues, but miata kill switches have been covered to DEATH by spec miata. They have both a negative killswitch and a positive one. take your pick and follow it.
Due to our setup, I generally don't think you need the 6 post expensive kill switches, you can usually move the battery over to the alternator side of the kill switch and it serves as the dump to ground should the alternator have a lot of excess charge when you kill it. This depends on which side (positive/negative) that you put the kill switch. let me dig up a few references.
Edit:
here is Dave's original instructions and someone pointing out the errant wire to IGN:
http://forum.specmiata.com/cgi-bin/u...1;t=002603;p=0
(the thread talks about the negative side kill switch, which is a 4-post setup on the battery negative and alt control signal from the ECU).
Still not sure how this fries your MS3 though...
Last edited by Seefo; 05-18-2015 at 09:50 AM.
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05-18-2015, 10:14 AM
#12
Boost Czar
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did you ran that silly wire from the ign side of the 80A fuse to the starter? and if so, which wire did you connect to? the Black wire on the spade connector or the b/r wire on the little connector? (I'm stil trying to figure out that point of that)
if you connected to the b/r wire on the connector, i'm assuming that's the issue.
also why/how are you using a 01-05 MS on a 93 chassis?
if you connected to the b/r wire on the connector, i'm assuming that's the issue.
also why/how are you using a 01-05 MS on a 93 chassis?
Last edited by Braineack; 05-18-2015 at 10:28 AM.
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05-18-2015, 10:43 AM
#14
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oh. lol.
two wires on the NB alt go directly back to the ECU. did you connect the ECU direct back to the battery through one of them by mistake?
not that i see how that could happen.
two wires on the NB alt go directly back to the ECU. did you connect the ECU direct back to the battery through one of them by mistake?
not that i see how that could happen.
Last edited by Braineack; 05-18-2015 at 11:16 AM.
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05-18-2015, 10:44 AM
#15
Cpt. Slow
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No, didn't make that childish diagram. Kept coming up in our research about 2 post kill switches, so we tried it and it worked, or so we thought.
I'm ready to bring it to miatacage (local) and just have them do it. This is ridiculous. No one has made a decent write up on the subject, and it seems like it's easy to **** it up.
I'm ready to bring it to miatacage (local) and just have them do it. This is ridiculous. No one has made a decent write up on the subject, and it seems like it's easy to **** it up.
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05-18-2015, 11:05 AM
#16
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it seems to me all you're doing is making sure the alt stays connected to the battery and putting a switch on the positive terminal. Seem pretty straight forward.
The addition of the resistor seems pointless. Keeping the alt always connected to the battery negates the need.
The addition of the resistor seems pointless. Keeping the alt always connected to the battery negates the need.
Last edited by Braineack; 05-18-2015 at 11:25 AM.
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05-18-2015, 01:10 PM
#17
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That battery cutoff switch diagram is straight out of the Spec Miata Wisdom(TM) handbook.
The 6-pole switches I use cut the main battery cable between the battery and the starter/alternator/fusebox. I place the switch inline with the main unfused wire between the battery and the starter motor to achieve this. It also has two pins that are designed to intercept/disconnect the coil power. I intercept the large blue wire that routes between the ignition key and the coils to achieve this. The 5th and 6th pins are a circuit that closes when the switch is opened (turned off). I route a wire from the alternator/fusebox side of the cutoff switch straight to the 5th pin, and I route a wire from the 6th pin through a resistor to ground.
With that method, when you flip the switch:
-The battery is 100% disconnected from the electrical system. No hokey "the alternator is still hooked up" horseshit
-The +12v feed to the coils is disconnected (in a Miata, if you intercept this just after the ignition switch inside the interior, you also cut power to the main relay/fuel injectors)
-Any residual power in the alternator/fusebox is dumped to ground via restrictor
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05-18-2015, 02:48 PM
#18
Cpt. Slow
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That's an awesome explanation, I think we did most of that except the coil part on the 5th/6th pin. Might have to mess with our 3rd/4th pin wiring too.
This is also what you do for NB kill switches?
This is also what you do for NB kill switches?
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05-18-2015, 03:02 PM
#19
It also makes the cutoff switch totally pointless. If the alternator is still connected to the battery with the cutoff switch off, then the switch is bypassed and the car should fail tech.
That battery cutoff switch diagram is straight out of the Spec Miata Wisdom(TM) handbook.
The 6-pole switches I use cut the main battery cable between the battery and the starter/alternator/fusebox. I place the switch inline with the main unfused wire between the battery and the starter motor to achieve this. It also has two pins that are designed to intercept/disconnect the coil power. I intercept the large blue wire that routes between the ignition key and the coils to achieve this. The 5th and 6th pins are a circuit that closes when the switch is opened (turned off). I route a wire from the alternator/fusebox side of the cutoff switch straight to the 5th pin, and I route a wire from the 6th pin through a resistor to ground.
With that method, when you flip the switch:
-The battery is 100% disconnected from the electrical system. No hokey "the alternator is still hooked up" horseshit
-The +12v feed to the coils is disconnected (in a Miata, if you intercept this just after the ignition switch inside the interior, you also cut power to the main relay/fuel injectors)
-Any residual power in the alternator/fusebox is dumped to ground via restrictor
That battery cutoff switch diagram is straight out of the Spec Miata Wisdom(TM) handbook.
The 6-pole switches I use cut the main battery cable between the battery and the starter/alternator/fusebox. I place the switch inline with the main unfused wire between the battery and the starter motor to achieve this. It also has two pins that are designed to intercept/disconnect the coil power. I intercept the large blue wire that routes between the ignition key and the coils to achieve this. The 5th and 6th pins are a circuit that closes when the switch is opened (turned off). I route a wire from the alternator/fusebox side of the cutoff switch straight to the 5th pin, and I route a wire from the 6th pin through a resistor to ground.
With that method, when you flip the switch:
-The battery is 100% disconnected from the electrical system. No hokey "the alternator is still hooked up" horseshit
-The +12v feed to the coils is disconnected (in a Miata, if you intercept this just after the ignition switch inside the interior, you also cut power to the main relay/fuel injectors)
-Any residual power in the alternator/fusebox is dumped to ground via restrictor
You realize the diagram doesn't do what you are saying right?
Ultimately I get what you are saying, but I think worrying about 12v on the alternator OUTPUT, but not worrying about the 12v on the kill switch terminal which is inside the cockpit next to the driver is...misplaced. Definitely though less 12v hot wires is better than more.
Or, you could avoid either situation and do the kill switch on the negative terminal, with 4 post switch.
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05-18-2015, 03:05 PM
#20
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It seems allowing the alternator dump back to the battery is kosher judging by my 5 minutes researching the subject. (i was looking for rulebook)
I think people prefer that method over the resistor as it can still damage an alt with all that amperage when the cutoff switch is opened. The only thing I'd change here is an inline 100A fuse or something in case of shorts--It offers no protection as is.
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