My RX-8 shakes at idle. What's going on?

Your RX-8 should not shake or vibrate at idle. However, you will feel vibrations in the shifter (manual transmissions only) because the shifter is mounted directly on the transmission.

Possible reasons for vibrations at idle:

Broken engine mounts:

The right hand engine mount is prone to failure due to heat from the engine. There is a TSB for this issue, which will replace the failed mount with one that has a heat shield:

2004-2005 RX-8 vehicles with VINs lower than JM1FE******154999 (produced before May 6, 2005)


Some vehicles may experience the following symptoms.

- On manual transmission vehicles, when decelerating in 3rd gear with engine speed less than 3,000 RPM at approximately 30 MPH (50km/h), then quickly depressing the accelerator pedal again, a hesitation may occur. This symptom can only be observed in this engine speed and vehicle speed range.

- On automatic transmission vehicles, when at a stop in D range, excessive engine/body vibration may occur. This body vibration does not occur in P or N range. Depending on the driving condition or engine condition, the RH side engine mount rubber may deform. As a result, the RH side engine mount can crack. As a mass production change, the material of the engine mount
rubber has been changed. To provide durability of the replaced RH engine mount, an engine bracket with insulator for RH side has been established together with modified engine mount for the LH side.

Customers having this concern should have their vehicle repaired using the following procedure. Replace the RH engine mount and modified RH engine bracket together with the LH engine mount.

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User Comments

does the dealership replace the motormount for the revised version for free? or does this come out of my pocket.?
Should be under warranty
i replaced my motor mounts, coilpacks sparkplugs and wires....and i still have a vibration at idle....????
if you still checks two more things it can be One being the throttle body (gets dirty from carbon etc) or the torque bar (the beam down the middle of the car (only if is makes noise when it vibrates) Knowlege from 1. rx8club . com web site 2. from local rotary mechanic
My 04 has been shacking at idle , and some times juddering up to 3k I did an ign test the other day and found both trailing plug coils are not fireing , I'm sure this is why
Any ideas on what it could be when my csr idels it shakes a little But as soon as i rev it stops only does it on tick over

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