I have an 04 MT with 56,000 miles. New plugs and coils at 45k. Only mods are springs and a K&N intake. A couple of months ago, I was having an issue with low power at highway speeds, and occasional stalling when coming to a stop. The stalling issue occured only twice, two days apart. After the second occurance, the car wouldn't start until I followed the deflooding procedures. Checked plugs and wires, didn't find anything. Cleaned the MAF sensor, and found a broken O-ring in the process. Replaced that, and things have been good since. Power normal, smooth idle, no stalling, 19ish mpg.

Today, the car seemed to be struggling on the highway. Running about 65 mph in 6th gear. Virtually no acceleration without downshifting. Got into town, and idle was rough. Had to give it a little gas to keep it at 1500 rpm or so to smooth it out. Pulled into work, and the car stalled. It started again, but had to crank for 8-10 seconds. Idle still seemed a little rough. All three stalling incidents have happened in high temps, 90 degrees or higher. Haven't noticed any stalling or power loss on cooler days, and the power loss only seems to be in higher gears at highway speeds.

Oil level is good, changed every 4000 miles since I've owned the car. (Last 20,000 miles) Temp gage reads normal. Thoughts? Is it time for a compression check?

 

Cat?

 

Don't know. How do I check? Wouldn't I have a continuous issue if the CAT was clogged?

 

Does sound like the CAT, mine was similar and CAT was clogged. Do you have any CEL? Bring it to someone who can take off the CAT and have a look inside it.

 

No CEL. Had one a couple of months ago for the secondary air pump. Replaced that and it hasn't come on since then. Car ran fine last night and this morning.

Thanks for the input. I'll see if I can get my local mechanic to look at the CAT.

 

Thats the same CEL I had as well before the CAT went...P0410
See https://www.rx8club.com/showthread.p...ighlight=p0410 posts 16 and 17

 

Yeah, I would say it's most likely the cat. I have the same year RX8 and discovered my cat was starting to quit at 63,000 miles when I removed it recently to rebuild my tranny. If you remove the cat (not really hard to do), take a look inside. I could see the packing coming apart and actually stuck on part of the screen. Even though I didn't encounter the issues you have, it was not far from doing that. The good news is that it's time to upgrade to a high-flow cat or race pipe!!!