okirx8

Hello from Japan,

I have a 2004 JDM, 5 speed. When i bought it, there was this vibration at idle that drove me crazy. After registering on this site, I started to look for solutions and started down the long road of repairs:

1. Engine mounts: changed them both. did not solve the issue
2. Cleaned the MAF sensor: did not solve the issue
3. reset the ECU (brake pump and did the hold the milage reset) did not solve the issue.
4. changed spark plugs: did not solve the issue
5. changed air filter: went back to stock one. prior owner had K&N one. did not solve the issue.
6. changed coil packs and wires: did not solve the issue.
7. had Mazda plug the car in to the diagostic. said nothing was wrong.
8. had a compression check done by Mazda: with 8.3 being new, my 3 readings on each rotor were an average of 8.2 (motor is fine)


i use only mazda oil (they do all service to the car). I only use premium fuel (96 oct). I replaced the steering rack when it went out and also replaced the coolant tank because the sensor was bad. I have no CEL going off. no issues now other than the crazy vibration at idle. i feel it through the gear shift and the steering wheel. through the seat..... driving me nuts.

any ideas/help would be much appreciated.

thank you.

RX8Soldier

iTrader: (24)

clean your eccentric shaft position sensor with electric contact cleaner. Then do the 20 brake pedal stomp NVRAM reset.

wcs

iTrader: (2)

Ya ... well that ^^^ and the car just naturally has a vibration at idle.

The stick shift is connected directly to the transmission, there is no linkage to soften the vibration.

RX8Soldier

iTrader: (24)

^^Correct.
I was under the assumption that the OP is suffering worse than normal vibrations?

wcs

iTrader: (2)

Hard to tell from his post, that's why I just thought I would throw it out there.

I would be willing to bet that if you or I got in to the car we would be like ... so where's the vibration again?

okirx8

thanks for the feedback. I should have been more specific. the vibration is worse than the regular little shakes the car normally has. it never actually stalls, but rpms drop when the a/c relay goes on and it gets really bad. if the engine fans kick on, the idle actually goes up and the shake disappears.

some more info that i should have mentioned as well: when i reset the ecu, the car is fine for a day or two. then goes back to the bad vibration at idle.

i drove one down at Mazda (gave me one as a loaner) and it did not do what mine is doing at idle. it had a regular little shake through the gear lever, but nothing like what mine does at idle where it can be felt through the seat, steering wheel, and shifter.....

Socr8tes

I've got the exact same issue. I've had the car since new and it's definitely not normal. I can describe it as a medium amplitude, high-frequency vibration. The idle just grinds when the RPM gets low enough. Much worse when AC cycles on. It you figure this out, let us know.

RX8Soldier

iTrader: (24)

Have you done any troubleshooting/elimination, like the OP did?

wcs

iTrader: (2)

Do you have any mods?
Like an exhaust or something that could be rattling against the Power Plant Frame (PPF) when your idling?

Wow to be feeling it in the steering wheel, strange.

Still sounds like the motor mounts to me, but you say both have been replaced.

Has the car been in an accident or anything?

Socr8tes

I did all the same things as the OP except change engine mounts. I also checked PPF alignment. I didn't check compression since its a brand new reman.

No mods, no accidents.


Edit: okay, 1 mod - BHR coil kit installed.

Mazurfer

Do you have a way to check the rpm's other than the gauge in the car?
If you have cleaned the MAF? If so, then get some Throttle Body cleaner and clean that throttle body.
Let me know if it helps please.

Socr8tes

I don't mean to highjack the post, but I have some new symptoms that may help shed some light on the problem. Here's what happened this morning:

- Engine was warm, had been driving for ~45 min. Defroster was on for most of the trip.
- Stopped at a red light. AC compressor kicked on. RPMs swung down to ~500, up to ~1500 then stabilized around 850.
- Drove another 3-4 miles, then ride got very jerky, especially during shifts. I held the clutch in and RPMs were hunting again.
- Engine then stalled. I had enough momentum to coast to an Advance Auto parking lot.
- I waited a few minutes and restarted. Tach still swinging around, then finally stabilized. I got out, opened the hood, pulled off the engine cover, then the engine just stopped. No sputter or anything, just off.
- I got back in and tried to restart. No crank. No click. Full lights on dash. Now at this point, I was already making phone calls, so it's *possible* I was so distracted that I forgot to depress the clutch, but I doubt it.
- I then walked into Advance and had them check my battery, starter, and charging system. All checked out okay.
- Was then able to drive the remaining ~10min of the trip with no issue.

The reman engine has about 3000 miles on it, and I remember the idle getting progressively rougher on my previous engine too. Doing a search here, I found the transmission neutral switch is the likely culprit for this morning's episode. Could this also cause a constantly rough idle?