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Coupes & Convertibles Mazda Miata Mazda MX-5 Miata Starting and Stalling Problems
58 messages, Last post on Nov 09, 2009 at 3:43 AM
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Replying to: cwybenga (Apr 19, 2008 4:49 am) |
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Replying to: branbuffy (Jun 03, 2008 6:36 am) You've replaced the plugs, so next thing to check are the plug wires. I've replaced mine twice already (every 30k). That's most likely. Do the 99s have an ignition coil? If so that would be my next guess. Beyond that I'd look at the fuel system - filter, fuel pump, etc. |
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Replying to: ateixeira (Jun 03, 2008 7:06 am)  So the car was taken back to the garage (towed)  and the mechanic ordered a new ignition coil saying 'that should fix it". Jeez I seriously hope so. Can an ignition coil really be the problem? Wouldn't sulphur smell lead to the catalytic converter?  I live in a super small town and the closest Mazda dealersip is 3 hours away! I haven't taken that route because I totally trust my mechanic -he's not a swindling type. I just want to know as much as I can. Knowledge is power. |
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Replying to: branbuffy (Jun 10, 2008 11:23 am) Basically you replace things in order of cost, cheapest stuff first. |
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Replying to: branbuffy (Jun 10, 2008 11:23 am)
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Replying to: cwybenga (Jun 11, 2008 4:27 am) |
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Replying to: cwybenga (Jun 11, 2008 4:27 am) 
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Replying to: ron77 (Nov 19, 2007 6:56 pm) Fuel filter is already replaced and the ignition is also checked, nothing helped. Ron, do you know what caused the problem? Thierry. |
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Hi everyone. Without boring you all to death, I have had EVERY single problem with my Mx5 described in this forum. I have had it since new, and probs started at 10,000 kms with the low rev drops/ stalls at intersections and has gone all the way to spluttering and stalling and not restarting for 20-30 mins. Has been at repairers from 1 day to 3 months and until today has NEVER been solved. BUT!!! One word COIL! Let me explain... They have TWO coils driving 2 cylinders each. The coils in MX5's/ Miata's begin to fail, not by dying by by DIMMING. (Induction dimminishing intermittantly) As the spark in one coil becomes weaker with it's partner coil, your car Will idle erratically on TWO cylinders. (Engine also 'pinks' as lack of spark uses the compression to finish the explosion, once its at the top of the cylinder movement) The failing one IS producing a spark, but is a little dim orange one not a big blue BANG! The fuel doesn't completely burn and gives the illusion of the Fuel/air ratio been out. (You can smell raw fuel yet normal exhaust at the same time) The computer is constantly trying to adjust the fuel to match the info from the caddy convertor, which is a mixture of 2 correctly burning cylinders and 2 that are filling with raw fuel. Hence- idle up down, purr, choke, stall etc. Then it will not restart as the plugs have drowned in unburned fuel deposits and raw fuel and the spark is too weak to combat this. The failing coils primary resistance is too high from being hot, ie 2.0 ohms + instead of 0.72 to 0.94 ohms to chuck out a good spark, which is why it restarts when it cools down. Then, wherever the weak link in the coil is can suddenly make a good contact again- and away she goes for another year... then suddenly... she won't restart after a short run...(#$%  **#) I was fooled doing the 'It's either fuel (theres tons of it) or no spark" tests, as when removed, the plugs WOULD fire when the lead was attached to the plug and the plug earthed on the engine to test. I finally noticed when faulting, 2 cyclinders produced a blue bright spark, and the other 2 produced a dim orange spark. The secondary coils (that the leads plug into) read 12k ohms each as they should so had not been investigated further. I took the coils out completely (easy as- took 2 minutes) and measured the primary coil underneath the housing and got my answer. (finally- $4 grand of repairs that never worked later...) The car has not run correctly for 9 years and today, after putting new coils in (20 minute job to change wires over and install) and she goes like a bat out of heck now. DON"T just do one coil... do both. Once this is done, check you have the NKG B5 sparks- (Cold plugs) not the NKG B6 (hot type) as they self clean really well. Both are specced by mazda- but are factory fitted with the B5's..Then short a wire between GND and pin 10 in the Diagnostic plug to by pass the ECU and see if it idles at 700-850 revs at full temp. If not, you mixture is out, and the air bypass is the screw under the cap on the throttle. CAREFULLY - Clockwise is richer (lowers the revs) and anti clockwise weakens the mix (increases the revs at idle) You will hear the air start to 'wisk' thru the manifold when you start to get it right....After this, the computer will run your car correctly. I chewed the ear of my Mazda dealer / repaired today, and he finally ADMITTED they had known that the coils cause this fault in many many many MX5s and have replaced TONS of them with all the symptoms described in this forum.... but are encouraged to blame the fault on the cars been just old and encourage the owner to purchase a new engine as the fault could be 'Anything' (yeah right). I am being 100% serious that he said this.. Good luck =) Good luck.
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Replying to: philmworks (Apr 07, 2009 10:34 pm) My car is in the garage (again) at the moment, still for that problem. I have already replaced one coil that completely failed, BUT not the other one! With some luck I can finally have it fixed. |
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