I have a 2005 Mazda RX-8 GT Shinka addition, with an automatic transmission. There is just over 60,000 km's on it. General location is southern Ontario, Canada. For the past 3-4 weeks, I have noticed what I seem to think is excessive vibration in the car while the car is idling at a traffic light or stop sign etc.

It's not like the entire vehicle is vibrating or shaking, but it is enough that the sterring wheel, driver and passenger side mirrors, and Rear View mirror are visibly shaking to some extent. Vibration can also be felt in the driver seat. The check engine light is not on, and there are no other warning lights coming on to indicate any kind of serious issue.

It also does not start this vibration immediately after ignition, but only after about 5-6 minutes of driving. Another interesting thing is, if I am idling at a light or whatever, and it is vibrating, if I put the vehicle into Neutral, it immediately stops. If I put it back into Drive, it starts again. Additionally, there are no issues while the vehicle is in motion, everything runs smooth.

I have taken it in to a local Mazda dealership, and they could find nothing wrong. They checked the computer, and everything was normal. They went over the entire engine, and said it was in excellent running condition. They inspected practically everything else on the car including engine mounts, brakes, suspension, exhaust hangers, axles, transmission, etc and said that the vehicle is in excellent condition.

Am I being extremely picky about this, or can someone suggest a possible cause / solution? I know that prior to the 3-4 week period that this started happening, that I had never experienced this issue in this vehicle, so I know it can't be normal. Any suggestions would be appreciated.

. Replace the platinum spark plugs with the same ones that came in the car.

. Drop and clean the transmission pan, change the filter, and refill with Mercon V. Living in Canada, I would use Mobil 1 Synthetic Multi-Vehicle ATF.

. Use full-synthetic engine oil and premium filter (e.g. Purolator PureOne). Change oil and filter every 10,000 km or 6 months, whichever comes first.

This should allow your car to idle as smoth as silk.

I was going to say check the engine mounts but nm you said they already checked those.

Thanks for the informative reply. The sprak plugs were replaced last fall by Mazda, so I think that can be factored out. Also, I have the oil changed every 4 months by Mazda, and I'm pretty sure they are using full synthetic.

This issue really seems to be transmission related, as the vibration stops when throwing it into Neutral. What I don't understand is why it doesn't begin to happen immediately, it takes 5 or 6 min before the vibration starts, and only while the vehicle is not in motion.

I have also heard that many people have experienced issues after replacing transmission fluid, and that it is not recommended. Perhaps I'll give it a try, as this seems the most logical solution. It's just funny how the transmission seems to be operating normally otherwise.

Thanks again for the info, appreciate it.

Call the mazda corporate office and schedule and appointment to a dealer from them. Demand to replace the engine support. I had mine replaced. 2005 rx8 is known with brittle engine mount support

Don't use full-synthetic oil. Never ever on a rotary engine. Rotaty engines are supposed to burn oil and synthetic oil doesn't burn. I also have a rx8 with 48k miles on it and it doe skinda vibrates while idling at a light or so but its normal for a rotary engine.

My 04 rx8 is also vibrating strongly on ideling and after ignition and at D,R,N gears the check and auto fax stated left engine mount problem but at the garage when I left the car up I saw that the drivetrain seveerly shacks my mechanic said it could be a drive train or drive shaft damage that might require balance or even change
If you found a solution please let me know
Thanks
[email protected]

I have a RX8 2005 I just put a new manufactured engine in it from the dealership new spark plugs and wires from the dealer a new throttle body new radiator... my car does not vibrate while in park only while idling and reverse performs fine while driving...

Southerngirl, ensure engine and transmission mounts were torqued to spec.