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Where are you guys idling at stoplights after the car is warmed up without accessories and without ac? I just connected my obd reader and it's at 550rpm and sometimes 650 rpm. Right around that middle tack. I can feel a slight vibration when it idles at 550rpm. It seems stable, no flunctuation. But it does seem low, when I turn on lights and ac idles at stoplights around 650-750. Where are you guys idling at stoplights without accessories ?
 

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At stoplights without accessories it's right at that small dot at 550rpm. There is a slight vibration in the dash and my seat. If I turn anything on headlights ac wipers etc it goes up 100 rpm to 650 and the vibration isn't there. Does anyone feel this or it vibrating? It seems low and it seems like the motor isn't happy about it. Hasn't stalled or anything.
 

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Mine does the same thing. Connected my car to the OBD port and it idles at 500 to 600 rpm's. I can feel a slight vibration and feels weird but doesn't bother me, but I definitely thought it was strange. The car runs flawless, though. Maybe timing was put at such low speed to save fuel at idle, who knows... Only the Mazda engineers will know lol
 

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and yes it's all about fuel consumption- they should put in stop engine module in instead, but I'm still making 33 mpg with mine very aggressive manual trans driving :)
 

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and yes it's all about fuel consumption- they should put in stop engine module in instead, but I'm still making 33 mpg with mine very aggressive manual trans driving :)
I get about 34 mpg with very aggressive driving (A/C off). But since it's now May and temps here in Vegas are starting to hit 100 degrees, I get 32 mpg with aggressive driving (with A/C on) and 38 mpg slow driving with A/C on.

I guess it's only easy to get 40+ mpg with the A/C off. Once you turn on the A/C compressor, you lose 5 mpg (or more, depending on how you drive) easily.

My V8 Camaro only loses about 1 mpg with the compressor on. Looks like our little FrankenMazda is not happy with the compressor on.
 

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Where are you guys idling at stoplights after the car is warmed up without accessories and without ac? I just connected my obd reader and it's at 550rpm and sometimes 650 rpm. Right around that middle tack. I can feel a slight vibration when it idles at 550rpm. It seems stable, no flunctuation. But it does seem low, when I turn on lights and ac idles at stoplights around 650-750. Where are you guys idling at stoplights without accessories ?

Mine also vibrates every now and then while at a stop light in drive. The tach shows 500 RPM on the dash. Normally it idles at 600 RPM on the dash and there is no vibration. But there seems to be no rhyme or reason why it drops to 500 rpm's. My guess is these automatics have bad torque converters as I've had a few symptoms that lead me to believe the torque converter is on it's way out.
 

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Mine also vibrates every now and then while at a stop light in drive. The tach shows 500 RPM on the dash. Normally it idles at 600 RPM on the dash and there is no vibration. But there seems to be no rhyme or reason why it drops to 500 rpm's. My guess is these automatics have bad torque converters as I've had a few symptoms that lead me to believe the torque converter is on it's way out.
I have a 6 speed manual and my car still does it. As you know there's no torque converter stick shifts. :eek:

I don't think is that big of a deal, maybe like I said in my previous comment, It's engineered to run at very low RPM's during idle to save fuel.

Bottom line is that new technology in cars is getting us mechanically outdated because cars have changed so much in the last 20 years. Like this car for example, if I'm not mistaken it runs a 12:1 compression ratio with regular gas!! Back in the day having a 9.5:1 compression was good...
 

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Mine also vibrates every now and then while at a stop light in drive. The tach shows 500 RPM on the dash. Normally it idles at 600 RPM on the dash and there is no vibration. But there seems to be no rhyme or reason why it drops to 500 rpm's. My guess is these automatics have bad torque converters as I've had a few symptoms that lead me to believe the torque converter is on it's way out.
I have a 6 speed manual and my car still does it. As you know there's no torque converter stick shifts. /forum/images/ScionIAForum/smilies/tango_face_surprise.png

I don't think is that big of a deal, maybe like I said in my previous comment, It's engineered to run at very low RPM's during idle to save fuel.

Bottom line is that new technology in cars is getting us mechanically outdated because cars have changed so much in the last 20 years. Like this car for example, if I'm not mistaken it runs a 12:1 compression ratio with regular gas!! Back in the day having a 9.5:1 compression was good...
Hrrm happens with a manual too? Maybe it’s just the motor mounts at that RPM then. It’s not so bad that I’m worried about it. Just hoped it wouldn’t break after warranty. I’ll keep an eye out and report back.
 

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Hrrm happens with a manual too? Maybe it’s just the motor mounts at that RPM then. It’s not so bad that I’m worried about it. Just hoped it wouldn’t break after warranty. I’ll keep an eye out and report back.
Yeah, apparently manuals and automatics are having the same "issue". That at this point I don't even think there's one after reading many of us hear the same rattle. I have it hooked to my OBD port through the Torque app and everything looks okay, just like I said before I've never seen a car idle at ~450-550 RPMs before. My 16 V8 Camaro and my 2009 Cobalt idle at 650-800 depending on temperature and engine load.
 

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I get about 34 mpg with very aggressive driving (A/C off). But since it's now May and temps here in Vegas are starting to hit 100 degrees, I get 32 mpg with aggressive driving (with A/C on) and 38 mpg slow driving with A/C on.

I guess it's only easy to get 40+ mpg with the A/C off. Once you turn on the A/C compressor, you lose 5 mpg (or more, depending on how you drive) easily.

My V8 Camaro only loses about 1 mpg with the compressor on. Looks like our little FrankenMazda is not happy with the compressor on.
No fault of the frankenMazda!

On a car like a V8 Camaro...

+ You have a higher amount of air to waste power moving through ( the car is significantly wider and less streamlined, but perhaps just as tall ).
+ You have a transmission that needs to transmit over 4 times the torque, so the drivetrain losses make up a significant amount of load to move the car. The lower the load of the drivetrain is ( IE when cruising at a steady speed on the highway ), the higher % this is of the horsepower needed to move the car along.
+ That rear differential also adds to this drivetrain friction.
+ Your engine has over 3 times the displacement, and at a low load such as highway cruising, it also takes a big friction and pumping loss penalty.

The Load that comes with a ~3 horsepower compressor turning on easily disappears in the noise of all these losses.

But on our very aerodynamically optimized ( this car is smaller than a Prius ) cars, an extra 3 horsepower load is a big kick in the balls.
 

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The car does idle rather low, but you can thank Mazda for saving your fuel economy during city trips by running the engine at a low RPM. The sad thing is that if you upgrade the motor mounts to ones that aren't the wobble-squish units the car came with, then you get to feel this.
 
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