1995 Mazda 626 Idle Fluctuation

1962 MAZDA 626
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RDUKE
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  • 1 POST
I have a '95 Mazda 626, 4 cylinder. When the car is started, it idles at 2000 rpm. It stays at this rpm for a few minutes then fluctuates between 1500 rpm and 2000 rmp. However, the engine light remains off. Any ideas??? How do I test an EGR lift sensor (3 pin connector)? Thanks! RDuke
Sep 12, 2006 at 4:48 PM
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BUBBA_KOSKI
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  • 129 POSTS
just check the fuel and pump along with the transmission filter, give her a complete tune-up

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Oct 4, 2006 at 10:02 PM
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RAGS729
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Im not sure what a tranamission filter has to do with an idle problem? The idle could be so many things it's hard to say without some more info. How does the car drive, what does the idle go to when you drop it in gear, does it miss or run smooth? The list of things to affect idle is pretty extensive ( timing, coolant sensor, TPS, vacuum leaks and on and on). Check around the engine compt. for broken or dry rotted vacuum lines.
Oct 22, 2006 at 7:17 AM
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COSMO
  • ✓Experienced Mechanic
  • 347 POSTS
First thing I would check is to see if there is enough coolant in it, this will sometimes cause an idle 'hunt' also be aware that you might have an IAC (idle air control) motor concern....this is the unit on top of the t-body with a coolant line going into it witha connector on it.

I would not worry about the transmission filter (since it is not serviable) or the ERG valve at this time. But I would have it checked for codes anyhow even though the engine light is not on.

Cosmo...

Mazda Tech
Oct 22, 2006 at 9:48 AM
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Suggested Repair

Check coolant level first, since low coolant can cause idle hunting. Inspect the idle air control (IAC) valve on the throttle body and look for cracked or dry vacuum lines. Scan for stored codes even though the check engine light is off. Do not prioritize the transmission filter or EGR lift sensor at this stage.

Conversation Summary

The owner of a 1995 Mazda 626 reports that the engine idles near 2000 rpm after start, then fluctuates between about 1500 and 2000 rpm with the check engine light off, and asks how to test a three-pin EGR lift sensor. One reply suggested fuel, pump, transmission filter, and a tune-up. Another noted many possible idle causes and recommended checking vacuum lines and driving symptoms. A Mazda technician advised checking coolant level and the IAC valve, scanning for codes anyway, and not focusing on the transmission filter or EGR yet.

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