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Mazda MX-5 Miata Starting and Stalling Problems



  • cwybengacwybenga Posts: 4
    I have a 2000 miata that started choking and only running on 2 cyl's. Opened the hood and removed a plug wire and the other 2 cyl's started again. Took the car in because the engine light was on and test after test, changed the coils. Light was still on changed the front o2 sensor, light was still on, changed the back o2 sensor light was still on. My mechanic was stumped, like you I trust my mechanic even though he wasn't from Mazda. He was not convinced that the cat had enough km's on it to need changing since the price from Mazda was 1500.00. Finally had enough and got a cat from Nappa 450.00 and replaced it myself. No light on anymore. After 2500.00 in repairs the car is good as new. I am guessing that when the 2 cylinders crapped out that it put unburned fuel into the cat, causing more problems.
  • branbuffybranbuffy Posts: 5
    Is the cat welded on or clamped on? How hard was it to replace it?
  • branbuffybranbuffy Posts: 5
    Was your Miata within the Emission Warranty of 8 years or 80,000 miles? Given my latest Check Engine code PO420, I luckily will fall into the warranty and get my cat replaced some time this month. Or at least that's what I have been told. :surprise:
  • I have the same problem: The engine starts without a problem, but at the first stop light it stalls when I use the clutch... when the engine is warmed up the problem is gone.

    Fuel filter is already replaced and the ignition is also checked, nothing helped. Ron, do you know what caused the problem?

  • 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.
  • Thank you very much for post!

    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.
  • Heii, Excuse me but did you ever find the solution to the problem you had?
    Because people I have the same problem, I have a Mazda mx3, It doesnt start, well sometime it starts and then it dies, I hit on above 2 - 3 Rpm and it dies, I dont know what the problem is, We changed the gas tank and we charged the battery also. But we havent figured out what the problem is.. Can SomeBody help me.
    Thanks. Alrassam ;)
  • ateixeiraateixeira Posts: 72,587
    As they say, spark or fuel.

    Could be the fuel pump, or a bad fuel filter.

    On the spark side, how old are the spark plugs? My Miata also ate through spark plug wires every 30k miles, that may be the most likely cause if the wires are older. Beyond that check the ignition coil, too.

    I bet it's your spark plug wires.
  • tony125tony125 Posts: 1
    I have a MX-5 California -2001 and, guess what? It starts first thing then, after about twenty mins or so it starts to lose power and stops!! No engine light, no smell?? Have changed the puel filter, crank sensor and also had the coils renewed today and on the way home stoped for about ten minutes then wouldn't start again, after abou a half hour wait it started and got me home- I'm tearing (whats left of) my hair out. I don't know what else to change, I'd like to change the car but if it won't start I can't sell it!!
    Any experts out there please cuz Mechanics don't seem to know whats wrong.!!!!!!!
  • ateixeiraateixeira Posts: 72,587
    It must be heat related.

    How old are the plugs and plug wires?
  • mmaxeymmaxey Posts: 3
    I'm new to the forum, and signed up because I am having the same issues with my 1999 Miata as 'uniboy' in post #7 and havent been able to find a solution. Last year I changed my timing belt and water pump. In the past couple of days since I've been having this problem, I've changed the spark plugs, s.p. wires, coil pack, fuel filter, and fuel pump, and still having the issue. It will run great until it gets warm, then stumble, sputter, misfire, and stall. Once the engine is cool again, it'll start up nice and smooth, until its warm, then do it all again. Needless to say, it's undrivable until I find a fix.

    Does anyone have the solution? Please e-mail: M_Maxey_2000 at yahoo dot com
  • uselmanuselman Posts: 5
    Are you using mazda plugs. Sounds wierd but for some reason it makes a difference with these cars. I had a similar problem which is fixed now but I don't think we ever resolved what actually started it. They simply replaced my coil pack and plugs and also a converter that had gone bad in the process but the folks at Mazda were unsure as to what started it. They said it could have been the wrong plugs or extreme carbon build-up. I bought the car used and they were telling me that a lot of Miata owners especially older females tend to drive them too gently and that they need to be reved pretty good to blow out the carbon. You might try carburator cleaner and make sure you have Mazda plugs. Other than that maybe a bad sensor. Sorry I don't have something more definite. My brother knows a lot more than me so I'll check with him and message you back. Cheers- Greg
  • mmaxeymmaxey Posts: 3
    Thanks for the suggestion, I'm using ngk plugs and wires and have since I've owned the car with no problems. I'm starting to lean towards the cam position sensor giving me the issues, but I'm looking for some backup on that, haha. Thanks for the help. If you hear of anything else, please drop me a note.
  • uselmanuselman Posts: 5
    My brother said it could be the Idle Air Control Sensor. This sensor works once the car warms and controls air intake at stops. He said not to buy a new one because it most likely needs just to be cleaned. He said this is most likely the case if you do not have a check engine light on. Hope this helps. Good luck. All in all they really are great cars though. Mine is at 200110 miles and still runs really well. Starting to burn a little oil on long trips though but I guess thats to be expected with that kind of miles.
  • ateixeiraateixeira Posts: 72,587
    they need to be reved pretty good to blow out the carbon

    Ah, the good ol' Italian Tune-up.
  • I bet it's the Cam Position Sensor (CPS). This is a super well known issue for the 2001 Miata. Check out the forum on for help with it:

    Down the page some is even a photo of where to find the CPS if you don't know where to find it already. It's SUPER easy to replace and will probably cost you about $80 - $100 for the part. Undue one bolt, slide out the CPS, slide in the new CPS, tighten bolt ... you're good to go.

    You can pull the CPS out, give it a good cleaning, chill it with another cars A/C or another way, stick it back in and see if that temporarily helps. It might but you probably just need to get a new CPS. This problem is so common it's unbelievable. They need to recall the car over it. I just don't think there have been enough complaints. If you would like to file a complaint with the NHTSA then you can either call them or file a report here:

    Hope it works out for you.

  • mmaxeymmaxey Posts: 3
    Well, i just installed my new CPS. I let the car get warm then stall with the old one first, then put the new one in. I started it up afterwards and its still doing the same thing! Do i need to let the motor cool first?

    I need more ideas...

    I misspoke when i said I replaced the fuel pump, I did not. I replaced the filter. It's still hard to believe that's the culprit because I can rev it and accelerate just fine until the engine gets warm and then it fails. Is it really the fuel pump?

    Where is the idle air control sensor on a 99?
  • uselmanuselman Posts: 5
    I'm waiting for a reply from my brother about the sensors location. I've never dealt with one before. If it is your fuel pump the good news is replacing a fuel pump on a miata is rediculously simple. Mine had similar problems when the fuel pump was bad but I don't remember if it had to be warm first. Anyway if you want some info on replacing the pump let me know and I'll message you as soon as I hear back about the sensor. Cheers-Greg.
  • Hi, I have the same exact issue on my 2001 MX5. runs for a few hours, then stalls. I replace the fuel pump(very simple), but the issue continued... I just replced the CPS. Now, my car won't start. It sounds like it wants to start, but it doesen't. Do I need to mess with the timeing? I moved a sensor thta is located in the front by the pully where teh timeing scale is. Does that something to do with it? I removed thinking that it was the CPS(relize the '01 in the teh back side of engine), but then I placed it back. Does this sensor needs to be at a certain angle? Not, teh CPS, but teh one I moved by mistake....
  • Hi, I have the same exact issue on my 2001 MX5. runs for a few hours, then stalls. I replace the fuel pump(very simple), but the issue continued... I just replced the CPS. Now, my car won't start. It sounds like it wants to start, but it doesen't. Do I need to mess with the timeing? I moved a sensor thta is located in the front by the pully where teh timeing scale is. Does that something to do with it? I removed thinking that it was the CPS(relize the '01 in the teh back side of engine), but then I placed it back. Does this sensor needs to be at a certain angle? Not, teh CPS, but teh one I moved by mistake....
  • My 1990 starts great cold, but then after a minute or so runs very roughly(I think rich,but not sure)til fully warm, then runs fine.I have checked and replaced plugs,coils(ouch!),oil pressure,compression, replaced the air flow meter, and checked what I think is the air bleed valve-which has engine coolant circulate thru it-it seems to respond ok to changes in H2O temp...any ideas??
  • Here's my story:
    7 visits, same issues
    The last 2 trips, I bought the parts myself. The mechanic would've scalped me.

    6/15/2008 113815 rough idle
    Catalytic Converter 273.94
    O2 Sensor 427.95
    PCV Valve 16.75
    Valve Cover Gasket 104.47
    Fuel Injector Cleaner 116.5

    8/13/2008 119436 rough idle Unstick Idle Control Valve 74.72
    12/26/2008124293 rough idle Replace Idle Control Valve 554.78
    8/1/2009 133399 rough idle Catalytic Converter 98.79
    9/10/2009 135063 rough idle Fuel Pump 283.49
    Fuel Filter 129.72
    Coolant Temp Sensor 195.75
    Thermstat 122.97
    10/7/2009 136158 rough idle Coil Pack 235
    Wires 33
    Plugs 21

    Total pain - 2688.83

    I'm in for the 7th time today. Just want them to get it right. Hopefully no more money passes hand. All the parts have been replaced, some twice.
    Have they hit the root cause?

    John M
    Anthem, AZ
  • ateixeiraateixeira Posts: 72,587
    The cat and the O2 sensor are downstream, so those were just symptoms. The problem was spark or fuel. Unburned fuel made it downstream and that's probably what clogged up the cat in the first place.

    You can tell by the list they're looking at spark/fuel issues, specifically the ignition coil pack and the fuel filter and pump.

    I'd go one step further and if you haven't already replace the spark plugs and especially the spark plug wires. They last about 30k miles on Miatas. On my 93 I remember changing them twice, and both times it fixed a hesitation issue.

    Try that if you haven't already - and get good quality wires.
  • Hi all,

    My Dad has just got a 2001 plate mx-5 sport and it has not decided not to start, I am a mechanic and i had 2 of my mechanical mates over last night to look at the car. We have gone through the coils, ht leads etc and all seems to be ok. I am aware that the cam position sensor could be at fault and i have not as yet replaced this. The car then decided to start and ran (badly) for about 10 seconds. we then looked in to the fuse box inside the car where we came accross something called the key recognition system. having spent rather a lot of time reading the forums and testing out the car, I suspect that there may be something to do with the immobiliser (if fitted) or this key recognition system could be playing up. We have tried to find fault codes in the engine and also the electrical system, but nothing was coming up. By no means am i disregarding the Spark plugs, Coil units ht leads etc, but if people have already replaced these items and are still having difficulty starting the car, this in my opinion is where you need to look in to. I will keep you posted on how things progress, if they progress.

  • I was driving my car from NJ to MA during a recent rainy night. The car was operating perfectly. I stopped to fill up and drove about 15 miles down the highway and the car stopped. I started it and it went a short distance then stalled. This was repeated several times until I finally was able to get off the road. The car was towed to a repair shop who determined that I needed a crankshaft sensor replaced. They did so and when I returned to the shop and paid them, I drove about 1/4 of a mile and the thing acted just as it had been. I had the car towed to a Mazda dealer who put it on the computer and supposedly tested it in a variety of ways, drove it and could not replicate the problem. I paicked up the car, it ran normally until the next day when it repeated the poor behavior.
    Any ideas? I am afraid to drive the car any real distance. The stalling occurs much less frequently, but it does still occur.
    Since the engine itself doesn't appear to be the cause of the stalling I am assuming it is electrical in some way. Is there a wire that could be shorting out or pinched?
    Help!!! :cry:
  • right, quick update. not much progress on the car itself, but i ahve had my dealer call me and they have had a 2002 model in (2.5) and they found that it was having the same not starting problems as my dad's car has. they had it connected up and again it did not bring up any errors. they then went through the car wire by wire and found that the immobiliser system had packed in. they repaired it and it was fine. i will let you know how i get on.

  • I am single mom, need to know if this sounds right? He can't test the engine because it won't start all the way, it turns over but not all the way. First had an oil change and car started puttering...also had a squealing when I started it off and on... Not sure if related to engine not starting. Pls advise. Ms Session in San Diego.
  • ateixeiraateixeira Posts: 72,587
    I had a 93 as well, for 8 years.

    The squeeling is probably the belts. Annoying, but not likely the cause of the engine not turning over.

    So the engine won't physically turn over all the way? That's beyond what I'm able to trouble shoot. Sounds pretty serious.
  • I was told it was the crank angle sensor that I need to get the car running. My question is does this sound right? I am a single mom/and have only had my Miata a year. Thanks for any ACTUAL ANSWERS. :)
  • Thanks for the answer about the belts though....I think it's my alternator belt.
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