Mazda MX5 (1998-2005) - 00 1.8 Intermittent misfire problem

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Mon 19 Oct 2009 12:49
00 1.8 Intermittent misfire problem - CharlotteH
Over the last few weeks, my car sometimes starts with what sounds like only 2 cylinders firing, it idles (almost stalling) at 500 revs, has pitifully little power (it couldn't get up a hill) and reaches 3000 revs around 20mph. Then, a bit later, after the engine has warmed up (but not as soon as it's warm) the problem clears itself and it runs normally.
It first misfired in May and I was told it needed new HT leads (which I had done straight away), plus the plugs were cleaned and checked. It behaved itself after that until a few weeks ago when this intermittent misfiring problem started again.
There are no warning lights on the dashboard when it has this problem. It only misfires when I start it up, never (yet) when I'm already driving and it doesn't do it every time I start it up (about 1 time in 10 at the moment but getting more frequent).
The breakdown mechanic who rescued me last time couldn't identify a problem (the engine was running normally again by the time he arrived) but he suggested it might be a problem with the coil pack, cold start valve or engine management. But I'd need someone to look at it while the misfire was happening for any hope of a diagnosis (and I can't predict when it will next misbehave).
Before I throw serious money at this, does anyone have any suggestions please?
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Mon 19 Oct 2009 15:33
00 1.8 Intermittent misfire problem - bazza
Most probably the coil pack, it's a well known problem on the MX5s from this era. It's intermittent and the symptoms are exactly as you describe. Not massively expensive couple of hundred perhaps, and easy to change.
Cheers
Baz
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Mon 19 Oct 2009 18:28
00 1.8 Intermittent misfire problem - sumpnut
Check out the previous threads on similar problems for this model.
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Sat 16 Apr 2011 17:25
00 1.8 Intermittent misfire problem - chrisplum
Having same problem with our MX (W reg). Intermittent back fire from stsart up. Lack of power. New leads has not solved the problem and doesn't show up on diagnostic testing. The garage can't identify the problem but again suggest coil pack. Has anyone had this done and if so, does it resolve the issues?
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