Weird Issue / Check Engine Light
 

Brief History of my 2004 rx8. Have had RX8 for about 1.5 years. Not original owner. Got the feeling previous owner didn't know what he was doing, but I knew the warranty status and sure enough about 6 months later got a new free engine. All work on the car done by Mazda dealer (mostly small things). Get oil changed there too. Recently did a compression test, and they said it was "best they had ever seen."


Here is the problem:

I live in Canada, it gets COLD. Was down to -25 C. Started it up, and let it warm up for obligatory period, and drove to store. Started doing a weird RPM thing a few miles down the road where the RPM went up and down and up and down, like it was revving on its own. Chalked it up to cold weather. Came out of store, it started and had NO power or RPM even with accelerator floored. Like the engine wouldn't engage -- only curb idle speed. Turned it off. Noticed the fan was still on. Turned the ignition to half way, turned off... fan turned off. Started again, and it was fine. I mean just fine, full power. But check engine light is still on. Drove it to my girlfriend's house, and then in the morning back home with no issues. Haven't driven since (this was a few days ago).

Any ideas?

1st idea:
Get the code read to see what the code is for.



Idle rpms jumping around when the engine is bone cold in really low temps is normal. CEL is not. But it could be anything from an unrelated "gas cap is loose" to something telling you that it's in limp mode because it can't read something it should be.

Yeah, I would have to take it in somewhere to get the code read. It's not in limp mode fortunately... I know what limp mode is from when the old engine failed. :D. Checking gas cap is a good idea, maybe it froze or something.

There are several different versions of limp mode. OMP limp mode is different from APP failure limp mode is different from cold-engine limp mode, etc... Just because you experienced a different one doesn't mean you don't have one engaged now.

The gas cap reference was just to the lowest possible cost/danger CEL there is.

In the US, most autoparts stores will read the code for free. If you don't have any places like that up there, then for less than the cost of a diagnosis fee at a shop, you can buy your own code reader or an OBD2 bluetooth dongle plus a free app on your smart phone to read it.