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#21
Gary Moser

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plugs 1 and 4 fire together as does 2 and 3. only one coil fires once in the first couple of revolutions then nothing.

 

have pretty much eliminated the immobilizer circuit after spending a long time on the phone with a Mazda technician.

 

replaced several fuse that they recommended even though they tested good.

 

something is not telling the coils to fire



#22
davew

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Have you scanned for diagnostic codes. If you get a handfull of codes, record them, clear and try to start again. Then rescan.

 

I would guess you have one of 3 things wrong, cam sensor, crank sensor or air flow meter. When any of these do not sense movement of cam, crank or air it will shut off the system.


Dave Wheeler
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#23
Gary Moser

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shows no codes, cam and crank position sensor swapped for ones off of a running car



#24
FTodaro

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I have had to fix or repair many issues in our miata's over the years but last summer when i developed a miss in my VVT under a load, it was one of the most frustrating repairs to run down. Electrical issues are a bitch.

 

No need for me to go into the details of what it was but my point is that you have to start eliminating as many possibilities as you can.

 

It can be costly, but my first suggestion is that you have to be sure that the replacement parts you are swapping are in deed good. so i would either use new parts or if its used that you do one at a time and then you put that part back on the original car and confirm that it still runs, in other words verify that that used part works before and after you used it.

 

The last thing i replaced was the problem, the wiring harness.

 

You might just start there.


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#25
Gary Moser

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there is a condensor mounted on the back of the head, anyone know what it does? I plan on replacing it with a new one.

 

been told to verify that the fuse box itself is supplying power to the fuses

 

will be cleaning all grounds that I can find

 

have finally been able to contact a Master Mazda mechanic willing to stop by and look at it



#26
Gary Moser

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had a Master Mazda Technician spend 6 hours diagnosing and scanning the car

 

two things stand out as being wrong, the egr valve is on and gets hot and the trigger voltage to the coils is always on and constant

 

tested the coils individually and they are good, for some reason the ecu is sending a constant triggering voltage to the coils

 

crank and camshaft position sensors are working

 

maf is good



#27
Gary Moser

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did scan for codes, none present except for egr

 

refernce voltages correct

 

grounds and power leads all good



#28
davew

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I have not gone out in the shop to verify this. But in general the ECU does not supply 12 volt source to any controlled device (EGR, Injector, O2 sensor). It will control the ground as a way of turning things on or off. The ECU does supply the 5 volt reference to sensors (TPS, ECT, etc.) 


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Dave Wheeler
Advanced Autosports, the nations most complete Spec Miata shop
Author, Spec Miata Constructors Guide, version 1 and 2.0

Building Championship winning cars since 1995

3 time consecutive Central DIvision Champion car builder 2012-2013-2014

2014 SCCA Majors National point Champion car builder

2014 SCCA Northern Conference Champion car builder, Spec Miata (Burdzy) and T4 (Bender)

2014 SCCA Runoffs winner, T4 (Bender)

2014 Central Division Champion, ITS (Wheeler)

2013 Thunderhill 25 hour winning crew chief

2007 June Srints winner, (GT1, Mohrhauser)

Over 200 race wins and counting.
www.advanced-autosports.com
dave@advanced-autosports.com
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#29
Gary Moser

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with the ecu disconnected and the ignition on, we were able to fire the coil by supplying 12 volts to the trigger wire



#30
davew

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Again, I have not studied a wire diagram.

 

Typically the coil is switched on and off by the ground side of the circuit. The ground side is controlled by the switch mechanism (points on an old car, ignition module on middle aged cars, and ecu on a new car). So if the ecu is unplugged, the ecu is not grounding that side of the circuit. If by touching the power side of the circuit, the spark fires, you by default have to have a always grounded situation in the ground circuit. Remember that a coil fires when the field is built up (power and ground are applied) and fires when the field collapses (either power or ground is removed). If both power and ground are constantly applied, the field never collapses and you never get spark. This is basic high school automotive theory 101.

 

I would look for a ground circuit that has a pinched wire someplace on that coil.


Dave Wheeler
Advanced Autosports, the nations most complete Spec Miata shop
Author, Spec Miata Constructors Guide, version 1 and 2.0

Building Championship winning cars since 1995

3 time consecutive Central DIvision Champion car builder 2012-2013-2014

2014 SCCA Majors National point Champion car builder

2014 SCCA Northern Conference Champion car builder, Spec Miata (Burdzy) and T4 (Bender)

2014 SCCA Runoffs winner, T4 (Bender)

2014 Central Division Champion, ITS (Wheeler)

2013 Thunderhill 25 hour winning crew chief

2007 June Srints winner, (GT1, Mohrhauser)

Over 200 race wins and counting.
www.advanced-autosports.com
dave@advanced-autosports.com
608-313-1230

Survive the 25, NASA Thunderhill - Survive the 25, NASA Thunderhill We have a Winnah! - Won their 1st race... Congratulations! Sponsor / Advertiser - Site sponsor / advertiser... support these guys! Donor - Made PayPal donation Bona fide - A bonafide Spec Miata driver




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