Vibration at Idle

Tiny
KENNETHUTHO
  • MEMBER
  • 2007 MAZDA 6
  • 2.3L
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 82,000 MILES
The car vibrates all over at Idle when I am at stop in a traffic with the gear in drive or reverse. It is more when the air-conditioner is ON and sometimes there is this short stumbling vibration like a shock-feel as the air-conditioner thermostat kicks ON and OFF which makes the rpm needle surge as if it will stall. Idling speed is between 650-700 rpm. I have changed the A/F ratio sensors B1S1, oxygen sensor B1S2, all 4 ignition coils, intake manifold, spark plugs, thermostat, air filter, cleaned egr valve, injector nozzles, throttle body, and MAF sensor. Still no improvement. My mechanic has checked all engine mounts and they are all ok. The vibration tends to reduce a little when I switch to neutral or park but it could still be felt on the steering, slightly. Car hesitates too.
Sunday, October 5th, 2014 AT 6:24 AM

3 Replies

Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
I believe the engine mounts are bad. Engine mounts would not be able to absorb the vibrations from engine operation when they are weak and sunken even though they might not be broken.

Read this guide on engine vibrations, it will help

https://www.2carpros.com/articles/vibration-noise
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Monday, October 6th, 2014 AT 9:02 AM
Tiny
KENNETHUTHO
  • MEMBER
  • 2 POSTS
Thanks KHLow2008. I think I will go ahead and change all 3 engine mounts. I am considering either of these brands, DEA or Anchor engine mounts. Are they good quality and would you recommend them? The Mazda OEM mounts are pretty expensive compared to these aftermarket brands. Also, do you think the weak or bad engine mounts would be causing a situation where the RPM needle stumbles deep as if the car will stall creating a short vibration when the AC compressor kicks on during it's normal cycling operation? I was feeling that could be an electronic issue? Or what do you think?
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Sunday, October 12th, 2014 AT 12:42 AM
Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
Sorry for the very late reply as I have been away all these while.

Engine stumbling when the AC kicks in is due to poor idling control and usually cleaning the throttle body and idle control valve would solve the problem.

See the guide below on how to do this

https://www.2carpros.com/articles/throttle-actuator-service
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Tuesday, December 9th, 2014 AT 9:12 AM

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