vibration and jumping rpms
 

So before i go ahead and buy a new coil pack for my 8 my maitenance guy said he wants to run some diagnostics on it first... my issues are a terrible vibration at idle and also the rpms jump at random intervals when im at idle also... it is not violent at all just very casually from about 750 to 1200... the codes im getting is a misfire and rear 02 sensor... could the 02 sensor be causing the misfire? and be a culprit of the vibration and idle issues due to atf ratio? if so i will start with buying a rear 02 sensor since i need one anyways the motor has about 25k on her and i have no idea how many miles the coils have on them since i re used them when i did my motor swap and my previous motor was used. any info would help... thanks

oh.. i also just replaced the plugs about 500 miles ago

Since you're receiving codes for the rear rotor, I would swap the coils and plug wires with the front rotor to see if the issue carries over.
Also, I live about 2 hours northeast of you if you care to try my used coils I have laying around.

i appreciate that... however i dont know what rotor is giving me the misfire i didnt check, probably should have ha, but i might take you up on those coils.... you interested in letting them go for good just in case i need them?

Sorry... I read your post too fast.
I read misfire and rear O2 and combined the two :)
But you did mentioned getting a misfire code, it should have told you what rotor.
Or if you can give us the code we can tell you.

And I have no problems letting my coils go.
Maybe we can trade since I would like to have some for troubleshooting (I'm sure some of your coils are fine).

that would be great... i am jumping into this on wednesday so i will repost where the misfire is coming from and maybe we can talk about those coils if i need them... all of yours are in good condition?

My coils were fine when I removed them.
Didn't have any issues with them, just upgraded to the BHR coils.

Not sure how drivable your car is, but you are welcome to come up here and we can swap the coils and test your current ones.
Though snow is coming Friday so this would have to be during the weekend.

if sunday allows it we could aim for then

No problem... just let me know and keep us posted on your findings Wednesday.

alright so my guy that was supposed to run diagnostics on my 8 today couldnt because his code reader wasnt linking so he just made a visual interpretation of what was going on... when you pop my hood you can see the motor shake pretty violently every couple of seconds or so and when the blower is turned on inside the car for air is gets worse... we threw some wires on today and SOME not much but some of the vibration went away... but now about every couple seconds the rpms will be steady at about 750 or so and then you will hear a very faint puttering and the rpms will struggle to about 500 and then jump back up to 1000... then leveling off at 750... im at a loss of words... any ideas?

Check the spark on each plug and see if one is weaker than the others.
They also make an Inline Ignition Spark Checker so you don't have to pull the spark plug out.
I got one from harbor freight for cheap:
Attachment 148876

Is anyone else in your area having similar complaints? Reason I ask is the station you pump may have switched to winter gas. Plugs are correct and gapped correctly?

plugs came straight from mazda so i would assume so

subbed.

I would like to see the outcome of this as my car does the same damn thing w/o the misfires though. I running the mazsport ignition and the plugs are brand new*raceroots* so i'm sorta at a loss myself. I also have a rich bogging issue under light pedal high load conditions.

I've got the idle jump but it flattens out when I push the clutch in...... just a neutral position sensor?