PCV or Vaccum leak

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2008 Mazda5 GT
I’ve had this random and somewhat phantom shake/rattle at idle (only when in gear) a short while back. I assumed it may be due to my stiffer eFocus RMM but the randomness (b/c it doesn’t shake/rattle all of the time) leads me to believe otherwise. It hasn’t really bother me much b/c the car has been a loaner. Well, car’s back and it makes it feel like a piece of crap – unacceptable.

I noticed the idle seems a little off. At full stop, idle drop ever so slightly by ~50-100 rpms. This seems to correlate with when it shakes/rattles. I cleaned the TB this past summer and relearn/calibrate it. I should redo this to check.

Considering the age/mileage (’08, 85K) of the car, I suspect the PCV is starting to get gummed up. Thoughts before I dive into this too recklessly? Anyone here replace their PCV? Quick search didn’t come up with much from past Mz5 owners. From the Mz3 world, looks a like tedious process of taking off the intake manifold to get access… Can it be done from bottom up?

It could also be a vaccum leak but I hate chasing this.


More I think about it, seems more like a vaccum issue since the car is under more load when idling in gear.
 
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This would be best to diagnose with a live data scan tool so you can monitor your live data stream for fuel trim and see if PCM is adjusting for anything.
If you have a leak it would compensate for it with more fuel.
You can also have dirty MAF sensor, dirty TB, bad bank1 O2 sensor, bad spark plugs.
I've not done PCV but it is same as Mazda 3, so would be same pita.
 
This would be best to diagnose with a live data scan tool so you can monitor your live data stream for fuel trim and see if PCM is adjusting for anything.
If you have a leak it would compensate for it with more fuel.
I totally forgot I have the toque app just have to find the ODB2 dongle Great suggestion.

You can also have dirty MAF sensor, dirty TB, bad bank1 O2 sensor, bad spark plugs.
I've not done PCV but it is same as Mazda 3, so would be same pita.
Wouldnt a restricted MAF and bad O2 sensor throw a CEL? Wouldnt hurt to try and clean the MAF but not going to touch the O2 unless I get a CEL. Car starts fine and drives fine otherwise and I really dont suspect plugs/coils. But wouldnt hurt to do spark plugs considering mileage. The car currently does not throw a CEL and starts/drives/otherwise rides fine.
 
Still can't find my ODB2 dongle :(
Plan b will have to be a bottle of propane and light'er up.

Does anyone have a nice diagram of the Intake Manifold and respective vacuum lines? Surprisingly, I can’t even find any good Mz3 images on Google; got a bunch of Mazda6 and Protg. On the plus side, found a site that sells silicone hose for ~$1/ft (and up depending on diameter) and made in USA! Woot woot!




EDIT:

http://www.jimellismazdaparts.com/showAssembly.aspx?ukey_assembly=299491

L301-18-741 Purge Valve
#18740

Stock Code: L30118741 ; L80118741; L801-18-741

Manufacturer: Mazda

Categories: Fuel, Intake & Exhaust Systems > Air Intake & Vacuum System

Assemblies: EMISSION CONTROL SYSTEM (2300CC); EMISSION CONTROL SYSTEM (2300CC)(W/O TURBO); EMISSION CONTROL SYSTEM (INLET SIDE); EMISSION CONTROL SYSTEM (INLET SIDE) (2300CC); EMISSION CONTROL SYSTEM (INLET SIDE) (2300CC)('03,'04 MODEL); EMISSION CONTROL SYSTEM (INLET SIDE) (2300CC)('05 MODEL


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