1999 Mazda Protege Low Idle RPM

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PAULFEYER
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hello! can somebody tell me what is the idle RPM for my mazda protege 99? because my mazda is at about 500in P and in D is about 400!!!! is normal??????
thank you in advance!!!!!!
Aug 21, 2006 at 12:26 PM
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MIKEYBDMAN
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  • 623 POSTS
[quote:b244a1a07a="paulfeyer"]hello! can somebody tell me what is the idle RPM for my mazda protege 99? because my mazda is at about 500in P and in D is about 400!!!! is normal??????
thank you in advance!!!!!![/quote:b244a1a07a]

It should be 650-750. Up to 800 with a/c on.
Aug 21, 2006 at 1:30 PM
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PAULFEYER
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[quote:7ee72985ce="Mikeybdman"][quote:7ee72985ce="paulfeyer"]hello! can somebody tell me what is the idle RPM for my mazda protege 99? because my mazda is at about 500in P and in D is about 400!!!! is normal??????
thank you in advance!!!!!![/quote:7ee72985ce]

It should be 650-750. Up to 800 with a/c on.[/quote:7ee72985ce]
THANK YOU FOR YOUR HELP! CAN YOU TELL ME HOW TO ADJUST THIS? BECAUSE LIKE I SAID MINE IS UNDER 500 ADN THE A/C DOSE NOT CHANGE MUCH!!!!!!!
Aug 21, 2006 at 1:41 PM
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MIKEYBDMAN
  • ✓Experienced Mechanic
  • 623 POSTS
[quote:b257e3270e="paulfeyer"][quote:b257e3270e="Mikeybdman"][quote:b257e3270e="paulfeyer"]hello! can somebody tell me what is the idle RPM for my mazda protege 99? because my mazda is at about 500in P and in D is about 400!!!! is normal??????
thank you in advance!!!!!![/quote:b257e3270e]

It should be 650-750. Up to 800 with a/c on.[/quote:b257e3270e]
THANK YOU FOR YOUR HELP! CAN YOU TELL ME HOW TO ADJUST THIS? BECAUSE LIKE I SAID MINE IS UNDER 500 ADN THE A/C DOSE NOT CHANGE MUCH!!!!!!![/quote:b257e3270e]

The computer controls the idle on your car. It uses the IAC valve to control the idle. You can check the resistance of this valve as follows.
Disconnect the negative battery cable.
Disconnect the IAC valve connector. Resistance: 7.7 - 9.3 Ohm [23 °C (73 °F)]
Measure the resistance between the IAC valve terminals by using an ohmmeter.
If not as specified, replace the IAC valve.
If the resistance is correct, then I would suspect a dirty throttle body or maybe a bad sensor input.
NOTE: if you try and clean the thriottle body, use only sensor friendly solvents and dont spray directly on any sensor, or electrical component.
Let me ask you this. Does you car run good other than idle? If not, you might want to check your fuel pressure system for supplying proper pressure.
Good luck
Aug 22, 2006 at 8:21 AM
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PAULFEYER
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  • 2 POSTS
[quote:40dad4a321="Mikeybdman"][quote:40dad4a321="paulfeyer"][quote:40dad4a321="Mikeybdman"][quote:40dad4a321="paulfeyer"]hello! can somebody tell me what is the idle RPM for my mazda protege 99? because my mazda is at about 500in P and in D is about 400!!!! is normal??????
thank you in advance!!!!!![/quote:40dad4a321]

It should be 650-750. Up to 800 with a/c on.[/quote:40dad4a321]
THANK YOU FOR YOUR HELP! CAN YOU TELL ME HOW TO ADJUST THIS? BECAUSE LIKE I SAID MINE IS UNDER 500 ADN THE A/C DOSE NOT CHANGE MUCH!!!!!!![/quote:40dad4a321]

The computer controls the idle on your car. It uses the IAC valve to control the idle. You can check the resistance of this valve as follows.
Disconnect the negative battery cable.
Disconnect the IAC valve connector. Resistance: 7.7 - 9.3 Ohm [23 °C (73 °F)]
Measure the resistance between the IAC valve terminals by using an ohmmeter.
If not as specified, replace the IAC valve.
If the resistance is correct, then I would suspect a dirty throttle body or maybe a bad sensor input.
NOTE: if you try and clean the thriottle body, use only sensor friendly solvents and dont spray directly on any sensor, or electrical component.
Let me ask you this. Does you car run good other than idle? If not, you might want to check your fuel pressure system for supplying proper pressure.
Good luck[/quote:40dad4a321]
THANK YOU. THE PROBLEM THAT I HAVE IS THAT THE CAR IS NOT SHIFTING IN TO GEARS ALL THE TIME. SO I SUSPECTED THE IAC. I CLEANED ALREADY THE MAF BUT WITH NO EFECT. THIS IS ON AND OF. SOMETHIMES IT SHIFT AND AFTER A WHILE IT DOSE NOT SHIFT. IT STAYS IN THE 2ND GEAR I THINK. SO I DO 40 MPH @ 3000RPM!!!
I AM GOING TO TRY TO CLEAN ALL THAT BECAUSE THE GUYS FROM AAMCO SAID IT IS NOTHING WRONG WITH THE TRANSMISION! ANY IDEAS?
THANK YOU VERRY MUCH!
Aug 22, 2006 at 3:56 PM

Suggested Repair

Idle is computer-controlled through the IAC valve, not manually adjustable. Check IAC resistance (7.7-9.3 ohms at 73 F) and replace the valve if out of spec. If resistance is correct, clean the throttle body with sensor-safe solvent only, and check sensor inputs and fuel pressure if the engine does not otherwise run well.

Conversation Summary

The owner of a 1999 Mazda Protege 1.6L reported idle around 500 RPM in Park and 400 RPM in Drive, with little change when the A/C was on. The expert said normal idle is 650-750 RPM, up to 800 with A/C on, and that the computer controls idle with the IAC valve. They advised measuring IAC resistance and replacing it if out of range, otherwise suspecting a dirty throttle body or bad sensor input, and checking fuel pressure if the car runs poorly otherwise. The owner later said shifting is intermittent and the car sometimes stays in second gear at about 40 mph and 3000 RPM; MAF cleaning did not help and a transmission shop found no transmission fault. No further expert diagnosis of the shifting issue was given.

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