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Discussion Starter #1
Hi Guys,

Just picked up this mazda6. Cool car, yet I've already noticed an issue that is really concerning me.

When I'm at a light and the car is idling, every now and then the rpm drops to just about 0, then shoots up to 2k, and then levels off again normally. It will do this intermittently. It has also dropped so low at times that it has actually died, although it starts right back up.

The weird thing is I have no check engine light or any codes. I've been told it could be a small vacuum leak that isn't big enough to trigger the check engine light. But at the same time, if it didn't trigger the light, I would think the idle problem wouldn't be bad enough to make the car stall.

Any other things I should be checking for? Sensors, something not connected, etc? I've had it looked over by a mechanic and he says he doesn't see any bad vaccuum hoses. Just trying to find out if maybe this is a typical symptom for these cars, and if someone knows the problem.

Any and all help is appreciated. Thanks in advance.
 

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Discussion Starter #3
I have the 4 cyl, not sure if its the 2.0 or 2.3, I'm inside my office right now. It is a 5 speed, has the sporty body kit with spoiler, not sure if that helps determine with 4 cyl.
 

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Discussion Starter #5
I have the 2.3, and my mechanic thinks its the idle control valve, comes as a whole piece with the throttle body. Does that sound accurate?
 

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Just got my 2006 2.3 (77xxx km) and I too have a loud idle and the rpms seem to lower on and off. I get somewhat of a shake too. I'm going to get mine checked as well to see whats going on.
 

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Regardless of miles, there are things I'd do to any car I bought:

spark plugs
cap, rotor & wires (if distributor)
fuel filter
air filter
PCV valve
clean EGR
run bottle of GOOD fuel system cleaner (Seafoam or Techron)
spray down throttle body
clean & coat batter terminals
new belt/s
change oil & filter
change tranny fluid & filter
drain & replace P/S fluid
drain & replace brake fluid
 

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I have the same EXACT problem and it is extemely irritating because I can't figure out what's wrong or find anyone who has actually fixed the problem. I don't want to start replacing stuff because it doesn't happen every time I get in the car so I could possibly be replacing parts for a year before I figure out what's wrong. I haven't taken it to the dealer yet but I think that they would look at the same stuff I did and everything I looked at is ok. You can look at a more detailed write up of what's going on with my vehicle here. I hope one of us can figure out what's wrong because it's very annoying and dangerous. Keep us updated.
 

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Discussion Starter #9
So I changed the throttle body/Idle control valve and started the car up. The dips in rpm were drastically less, although still noticeable. I'm thinking the computer may need to re-learn everything again since I unplugged the battery when changing it out. So I'll report back in a few days letting you know how it went. I'm hoping once I drive around a couple hundred miles, the idle will smooth out the rest of the way. As it stands, I let the car idle for 20 minutes and it never dropped low like before, only ever so slightly. I'm hoping that was it!
 

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Okay so this sounds EXACTLY like what happened to my friends cobalt when we TRIED to turbo it in his garage. As we started to try different tunes it got worse then better then worse again and it got to the point when the car would die at every light. The problem was that he had a BAD O2 Sensor.

:burnout:so check that
 
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