developed a rough but temporary idle?

2009 MAZDA MX5

78,500 MILES • 2.0L • 4 CYL • 2WD • MANUAL

SURFERGURUDUDE

MEMBER
2 POSTS

After replacing a 9-year-old battery my Mazda developed a rough but temporary idle. At every stop it will idle rough for about 5 seconds and then it's fine. It must be stopped to heal itself. If I'm coasting in neutral, it doesn't stop the rough idle until I'm stopped. Cleaning the MAS and throttle body didn't help.

Jul 19, 2025 at 12:51 PM

STRAILER

✓ASE Certified Mechanic
54,832 POSTS

This is typical of the vacuum leak, it takes a few seconds for the computer to adjust the mixture from its normal position to make the engine run smoothly again, this problem might get worse as the leak gets larger. Here is a guide and video to help with the problem, please go over both.

https://www.2carpros.com/articles/repairing-engine-rough-idle-issues

and

https://www.youtube.com/watch?v=LRKWV4Are5c&t

Please go over these guides and get back to us.

Jul 20, 2025 at 10:16 AM

SURFERGURUDUDE

MEMBER
2 POSTS

I removed and cleaned the throttle body and O ring with MAS cleaner and my idle is back to normal. It may have been the cleaning or maybe just making sure the hose clamps were tight, not sure, but it's all good.

Jul 21, 2025 at 12:10 PM

STRAILER

✓ASE Certified Mechanic
54,832 POSTS

Thanks for letting us know, we are here to help, please use 2CarPros anytime.

Jul 21, 2025 at 5:44 PM

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