# Dying Miata

**URL:** <https://community.cartalk.com/t/dying-miata/45465>\
**Category:** Maintenance/Repairs\
**Tags:** mazda, miata\
**Created:** [March 3, 2010, 5:47pm UTC](https://community.cartalk.com/t/dying-miata/45465 "2010-03-03T17:47:17Z")\
**Posts on this page:** 7\
**Page:** 1

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**Author:** ![bluemiataguy](https://avatars.discourse-cdn.com/v4/letter/b/85e7bf/32.png) [@bluemiataguy](https://community.cartalk.com/u/bluemiataguy)\
**Post date:** [March 3, 2010, 5:47pm UTC](https://community.cartalk.com/t/dying-miata/45465/1 "2010-03-03T17:47:17Z")

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I have a 1991 Mazda Miata. Lately, when I pull up to a stop, the engine will drop to a very low idle and usually stall - UNLESS, the headlights or parking lights are on! Then, the idle is just fine. Any clues? The car has approx. 146k miles, and otherwise runs great.

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**Author:** ![bluemiataguy](https://avatars.discourse-cdn.com/v4/letter/b/85e7bf/32.png) [@bluemiataguy](https://community.cartalk.com/u/bluemiataguy)\
**Post date:** [March 3, 2010, 5:48pm UTC](https://community.cartalk.com/t/dying-miata/45465/2 "2010-03-03T17:48:48Z")

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p.s. - the car is a 5 speed manual.

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**Author:** ![Joseph\_E\_Meehan](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/joseph_e_meehan/32/21_2.png) [@Joseph\_E\_Meehan](https://community.cartalk.com/u/Joseph_E_Meehan)\
**Post date:** [March 3, 2010, 8:04pm UTC](https://community.cartalk.com/t/dying-miata/45465/3 "2010-03-03T20:04:56Z")

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When was the last spark plug and wire change? This car needs them changed about twice as often as other cars. How bout the fuel filter? Ever changed?

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**Author:** ![circuitsmith](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/circuitsmith/32/40376_2.png) [@circuitsmith](https://community.cartalk.com/u/circuitsmith)\
**Post date:** [March 4, 2010, 1:55am UTC](https://community.cartalk.com/t/dying-miata/45465/4 "2010-03-04T01:55:21Z")

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Check the air intake plumbing for cracks. Clean the throttle body, idle air control valve and MAF sensor. Does this engine need valve adjustment? Get a compression test.

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**Author:** ![bluemiataguy](https://avatars.discourse-cdn.com/v4/letter/b/85e7bf/32.png) [@bluemiataguy](https://community.cartalk.com/u/bluemiataguy)\
**Post date:** [March 4, 2010, 12:33pm UTC](https://community.cartalk.com/t/dying-miata/45465/5 "2010-03-04T12:33:13Z")

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Good suggestions! Thanks, Joe and circuitsmith.  
But - can anyone explain why the car idles fine and doesn’t stall out when the lights are on???

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**Author:** ![Joseph\_E\_Meehan](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/joseph_e_meehan/32/21_2.png) [@Joseph\_E\_Meehan](https://community.cartalk.com/u/Joseph_E_Meehan)\
**Post date:** [March 4, 2010, 2:34pm UTC](https://community.cartalk.com/t/dying-miata/45465/6 "2010-03-04T14:34:05Z")

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A possible grounding problem.

When you have a mysterious problem, a good place to start is any past due maintenance issues. Once those are out of the picture, it makes the troubleshooting easier.

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**Author:** ![circuitsmith](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/circuitsmith/32/40376_2.png) [@circuitsmith](https://community.cartalk.com/u/circuitsmith)\
**Post date:** [March 4, 2010, 5:00pm UTC](https://community.cartalk.com/t/dying-miata/45465/7 "2010-03-04T17:00:25Z")

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On many cars the engine computer monitors alternator load and will raise idle speed to help maintain the current.

Next time try turning the heating/cooling fan on high instead of the lights.