2000 Mazda Protege rough start

2000 MAZDA PROTEGE
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GEODRAG
  • MEMBER
  • 1 POST
2000 Mazda Protege 4 cyl Four Wheel Drive Automatic 90.000 miles

2000 Mazda Protege starts at first key but for the first few minutes idles roughly. It feels like a fluctuation that is made very clear if I turn the ventilation on. It goes up to 1500 rpm only to slowly return to about 1000 or 900 rpm, where it then stays. Once the engine warms up, no other problems are apparent (is fine at stops). It appears to act like this only with a cold engine. The acceleration valve has been checked and is clean. No warning lights as of yet. I would much appreciate help with this problem as nobody has been able to figure it out. Thanks.
Feb 14, 2009 at 10:11 AM
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F4I_GUY
  • ASE Certified Mechanic
  • 3,302 POSTS
  • ASE Certified Mechanic
Hi geodrag,

Your idle fluctuation may be causing by an acting up idle air control valve (IACV), a vacuum leak, or a dirty throttle body.

First thing I would do is remove the intake duct, and give the throttle body and idle port(s) a good service with throttle body cleaner. This may solve your idle surging problem. If it doesn't, I would look into the IACV acting up.
Feb 14, 2009 at 6:09 PM
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