Hello everyone, I have a 2004 rx8 with 48K miles and 6 speed. The last 3 days something weird happened, at stop lights the RPM fluctuates like crazy from 1,250 to 2,000 over and over. Have you ever experience something like this? Any suggestions?

 

Transmission neutral switch. Search "Idle hunting."

 

Thx so much Mr Piper, I forgot to say that even while driving at low speeds, when the RPM drop below 2,000 RPM but higher that 1,250, the fluctuation issue appears.

 

sounds more like a vac leak to me especially if it is doing it when fully warmed up

 

You sound like a vacuum leak.

Have a listen for strange hissing under your hood.

 

lol hey just throwing out the possibilities. And you sound like a .... well ... over vacuum vaccuuming

 

Well go vacuum your garage.

 

Thank you so much guys, I will check for a vacuum leak. Today this is what happened: in the morning I started my 8 and the RPM went high (like 4,500 RPM), I pushed the gas pedal once and the RPM went down but the fluctuation issue appeared again. I turned off the ignition key and I waited like 2 mins and the vehicle started and warmed up fine. Driving to the office when I stopped at a traffic circle the RPMs went to zero and the car turned off. I re-started and started fine so I drove to y office. Have you ever heard something like this?

 

sounds like bad news bears to me ... .. lets cross our fingers and hope for teh best.

What is the car's maintenance schedule like?
last time spark plugs changed?
last time coils checked/changed?
last time car was flooded?

Give us as much detail as you can....

if recently purchased, did you get a compression test?

 

Thx for the fast response. My Rx8 is 2004 with 48K miles with 6 speed , I bought the vehicle 2 years ago with 42K miles, here is the maintenance that I’ve made:

42K miles: I changed sparks plugs, Spark plug wires and Coils.
42K miles: I changed the Oil, Oil Filter and gas filter
42K miles: I changed the coolant
45K miles: I replaced the A/C and water pump belt.
45K miles: I replaced fuel pump
45K miles: I changed the Oil, Oil Filter
48K miles I changed the Oil, Oil Filter
48K miles Throttle body cleaning
48K miles I replaced CAT

One day the dealer scanned the car and said that a Pedal Position Sensor can be the reason, but I don’t understand how a Pedal position sensor is involved in this issue.

I have read several posts regarding Apex Seals and Loss compression, but I don’t feel that my 8 is losing power.

I will appreciate any feedback.

 

The is the mechanical switch activated when the clutch pedal is pushed to the floor. The error could be a disconnected wire, a poorly connected wire, or the switch on the clutch pedal.

Sidenote: This same switch is the one that must be bypassed on the manual for a remote start to function.

The other clutch pedal switch controls the cruise allows cruise control to function when the pedal is at rest.