Rough running 2005 Mazda3 2.0, 5Spd Manual, 100,000Km

[jkmazda3]

Help. Engine vibrations is abnormally high for the last six month or so. No check engine light. No codes in ECU.

Engine was running smooth but I found the Passenger side fluid filled engine mount had leaked out, so I installed a new one and the vibration became very prominent especially with engine cold idling around 1K-1.2K. With engine warmed up and ~ 700 rpm, less vibration but still not smooth.

Removed and cleaned Mass Air Flow sensor with MAF cleaner. No change.
Removed and cleaned throttle body on both sides. Less vibration but not like it use to be.
Replaced sparkplugs with Autolite iridium. No change in vibration.

I’ve been driving it like this for nearly 10,000Km, hoping for some change to indicate which direction to trouble shoot.

Any recommendations as to what to check next???

[peterm15]

Have you checked the other mounts. Or is it possible the one you purchased was faulty, although I don't see a pass mount causing that many vibes.

[renownguyen]

i had changed my torn-up engine mount and it significantly reduced my vibrations. its possible that it can be a dirty/clogged EGR valve? its been mentioned around here and other mazda 3 forums. i havent been able to do it yet, cause the EGR is a bit of a pain to get at...but maybe you wanna check that out or read into it??

[jkmazda3]

I have checked all mounts and they are in good condition. No tears, no sign of damage. I beleive the new replcement passenger side mount is fluid filled, but it's very hard. Is it possible to get a solid rubber mount, which would be less efficient in dampening vibration?

I was looking for the Idle Control Valve to clean (other vehicles this is usually the issue), but it does not have one.

I have not found the EGR yet. Where is it located?

What about the "Variable Tumble Valve Solenoid" and "Variable Intake Air Solenoid Valve"? Can these cause rough operation and if so, how does one check then for proper function?

I do not think the PCV would causer this, but I will probably change it out anyway. It'll just take some time since I have not removed the intake manifold before.

Any ideas, recommnedations? I don't know where to start. But I rather not go to the dealer yet, I want to better uderstand the engine.

[stock3]

A vacuum leak can cause rough idle and lots of vibrations. Check all your vacuum lines.

[jkmazda3]

One more thing. When the engine is really warmed up, after driving at highways speeds for 15-20 minutes and come to a stop, it idles around 700 rpm and there is no vibration, you can't even hear the engine. But when you step on the accelerator the vibration comes up and you hear it and feel it. I looked for air leaks but could not find any place for un-metered air to enter. But I will continue looking.