First time I've seen this on the RX-8...

Shortly after starting the car, I was at a red light when I noticed that it was hunting for idle -- consistently sweeping from 1K to 2.5K RPM. Ext temp was 39F (4C) and engine was barely warm.

After a short run it was back to normal. Stopped to refuel, then shortly after, I noticed the oem OIL-P gauge showing very high -- mid way between mid and max. Stopped the car, checked everything -- nothing unusual. Start her back up and notice the OIL-P gauge doesn't sweep. Looks stuck. I smack the gauge housing a few times and the gauge resettles at about 2-3 notches above mid.

I am running RP 5W30 so a slight high pressure could be possible but this is the first time in 10K KMs of running RP that I have seen this.

I know that my plug wires are screwed. I know that my fuel pump is weak. BHR coils just installed.

Any explanations?

I've seen this on my wife's old Prelude and it turned out that the fast idle valve on the TB needed to be replaced. I've also noticed that since I installed the BHR coils, fast idle is reduced -- lower idle and for a shorter time. Possibly related?

 

idle issue: due to some reason the PID controls went out of their operating windows, causing PID swing. Possible causes:

- Leaking or clogged air intake system: dirty air filter, leak on some vacuum hose (the elbow connectors are very likely to crack)

- Dirty or malfunctioning throttle flap: Taking out and cleanin the throttle housing from time to time is a good idea anyways

- Dirty or malfunctioning MAF and/or IAT sensor: same wisdom

- Leaking or malfunctioning fuel injectors

- Bad Lambda (O2 sensor)

Oil pressure:

one occurrence I would blame on instrument failure, but keep on watching...

 

Well idle issue hasn't called back, but every time I start the car now the OP shoots to near max. I smack the gauge cluster a bit and it eventually settles to 3 notches above med.

Pretty sure that gauge is just completely useless but if anyone else has seen this I'd like to hear from you.

 

The OEM gauge is not actually an oil pressure sensor. It's more like an idiot light in the sense that it just senses pressure or no pressure. Where it rests in the range is not dictated by the actual oil pressure. I would not use it to measure your actual oil pressure. Just whether or not you have any.

 

was the clutch in or out?

sounds like the neural pos switch is going...

year and miles on car?

beers

 

The idle thing has happened to me a couple of times over the life of the car in very cold weather. It was always an isolated thing and never caused any lasting problems. Forget about it. As for the oil gauge, I have heard of nothing like it. Sounds like a bad sender unless hitting the dash really helps then it could be a bad gauge. Best of luck