NFernoEdge

Greetings everyone, having an issue that I haven't been able to match up to previous experiences while search old posts. I have an 04 Automatic, 53k miles. I recently had some misfires, diagnosed as failing spark plugs, replaced plugs and wires, already have BhR could.

After replacing I've noticed on hills when I'm in low gear above 4K my temp gauge starts to creep up, maybe 3 marks past normal op temp. It starts to fall back down right away and if I plug the OBDII when I see it moving up it's already falling back down. Fans work fine, but I've noticed backfires a bit more often when accelerating.

Any advice on how I should be diagnosing the problem?

Thanks everyone!

sonicsdaman

iTrader: (3)

Does it smell like coolant? Is it the original coolant from 04? When was the coolant last changed?
Is anything blocking the rad, or has hit the rad recently? Is it eating any coolant?

The cooling system as a whole can have a lot of things that will make a car over heat.
More of the common ones are for the rx8 are, lack of an undertray/foam around rad, bad T-stat, old coolant, plastic nipple on the rad cracked/leaking, old hoses from 04 cracking, fans/relays go bad, coolant return tank/cap, blown coolant seal etc.

Also, not trying to make you panic but if the dummy gauge on the dash is moving at all past normal operating position, the temp is already past the point in which damage may and most likely will occur.

NFernoEdge

There is a slight odor of coolant I think, haven't seen any visual signs besides the temp gauge.

I live in Hawaii so my car already tends to run on the hotter side. Is there any easy way to diagnose some of these causes? Nothing temp related on the DTC codes from my ODBII

NotAPreppie

You can test the coolant for exhaust gasses to see if you have a bad coolant seal.
Monitor the level of the coolant in the reservoir.

Also, leave your OBD adapter plugged in and see how high the temperatures get.

Also, when you say it backfires, what do you mean? It's pretty tough to make a stock RX-8 actually have a real backfire (where fuel ignites in the intake track rather than in the engine) unless something is very wrong.

NFernoEdge

I get this low popping sound from under the car, sorry if backfire is the wrong term.

40w8

Wow, sounds like you have some coolant water issues to track down.

You are lucky to be able to lower temp on engine and auto trans another way.

I have the 6 speed auto, but your 4 speed should also have a radiator inside the water radiator.

I took out the little gravel screen, and bolted a 18,800 tube type ATF cooler there for the ATF fluid.

I lowered the ATF 14 deg which also pulls some heat out of the water.

Guys with manual 6 speeds don't have that option.