Heya everyone, new rex owner here.

Bought me an rx8 about a month ago, used, 100k km on the counter and running fine till about a week ago. After about an hour of city driving, I found out my rex was lacking power, from what I read I'd say it looks like I got stuck into "Limp mode". I had power on the first and second gear, but could barely make it past 3k revs in third gear.

There also was some sort of clunking sounds as the speed went up. As soon as I noticed the loss of power I stopped on the side of the road, only to notice my idle was going way lower then usual, almost choking at one point (had to give it some gas to keep the engine alive).

I turned off the engine for a while and the idle came back perfect though the lack of power was still there. Came back home crawling and gave the car another go a couple of days later. Purred perfectly, as aggressive as I've known it. But again, after an hour of city driving, traffic jams and 10 minutes of high revs speed (80-100 km/h @ 4-6k rpm) then power went back out as I came close to 100km/h

From what I read so far, I'm enclined to think I'm due for a coil replacement, but I'd like to have a second opinion, as I'm quite a beginner with the rx-8 and in mechanics in general.

Thanks!
BTW, it's an '05 with 110k km under the hood. Not sure when (and even IF) the coils were changed. The bolts and bracket looked pretty rusted up.

 

Sounds like you CAT might be plugged up?

Sounds like it runs fine cold..and at low load levels till it heats up.....then it starts to loose power?

Or it could be a fuel delivery problem....commonly known as a crapping out fuel pump

Or it could be coils as well...

You would need to check a few things to make sure.....

 

From what I've read, the CAT would cause a white smoke from the excessive heat wouldn't it? Would a clogged CAT heat up faster too?

Both exhaust pipe seem to have a decent air flow with the engine running at idle and the beverage holder does heat up but only after an extensive drive.

Are there any test I can do in order to pinpoint my problem?

 

Unlikely to be coils, they don't get better/worse. Likewise a bad cat will be 'bad', not bad today, and good tomorrow.

If the symptoms only happen after a period of fast steady highway, it may be the primary gas filter (sock) inside the tank.

The 'for sure' diagnosis is to pull over on the highway, and roll the car from side to side, to slosh the gas around in the tank - if this works, and you get another ten miles at high speed before it chokes again, it's the sock.

Easier than it sounds to clean, see the DIY.

Let us know......

S

 

Here's the update:

Went for a drive yesterday, about 10 minutes of city driving to get to the highway, then 20 minutes of 80-100km/h and I started noticing the lack of power again. I got off the higway and stopped to test the idle, it was rough (went down to about 750rpm) but sustained itself, didn't come close to dying. I then shook the car as Stealth suggested with no immediate result, idle was still as rough and the power wasnt back (first and second gear were fine, third was deficient) so I made my way back home. About 5 minutes into the drive it seemed like the car picked up some of it's power and looked fine ?!?

I got hold of a OBD2 reader from a friend today and plugged it in to find a freeze frame "P0420 - Catalyst system Efficiency Below Threshold (Bank 1)"

I'm going to search the forums about it but at first sight, it looks like it's all caused by the cat

 

I would say a bad Cat.

 

Sounds like a cat, but a cat is just progressive - back pressure builds up at high power output until the car runs like poop.

Since idle is so easy, the idle is the last thing to be affected.

S

 

Haven't had the time to get the car in the garage and do some proper verifications till then, but I've used it carefully meanwhile and here's what happens :

At somewhere around 6k rpm, the car starts to sputter and lose complete power. I then got the flashing CEL light for misfire P0302, misfire in cylinder 2.

Next time I used it was for a ~300km drive, cruising somewhere around 100 to 120km/h the car ran perfectly except when I tried putting my foot down, as soon as I tried to get some power out of it, that's where it starts sputtering and completly lose power. If i drive carefully and accelerate slowly, I dont feel any problem at all. The entire trip was free of error codes (I now drive with a scanner on board). Used the car for about 20 minutes of city driving today, plugged it in and received a P0410 (secondary air injection issue), cleared the code and it didnt show back up for now.

Those codes keep throwing me in different direction everytime I plug in... I should go ahead and get it checked by the stealership but as I'm in between jobs right now, I'd much preffer to narrow my options and if I could do it myself.

Anyways, figured I'd better post it, maybe some of you guys will have an illumination.

Whatever happens, I'm going to a friend garage soon so I can work on the car, visual inspection of the cat, testing the coils, etc etc.

Oh and I'm not sure this is relevant, but after an hour of highway driving at 120km/h, the cat was nowhere red, so it doesn't seem to be overheating at all.

 

Quick update:

Checked the fuel filter as suggested by Stealth, it was perfectly cleaned. Still gave it a quick clean up and reinstalled.

Dismounted the air pump, bearings seemed fine, motor runs fine. Disassembled the air valve and cleaned it since it was nasty as hell, probably clogging up the air flow and causing the P0410, can't confirm that the code is gone as I didn't drive the car enough yet

Checked the cat as much as I could and it seemed fine.

Tested two coils and here are the results :
coil-1 : A to B : 1.52k
B to C : 8.14m
C to A : No reading

coil-2 A to B : 1.49k
B to C : 9.23m
C to A : No reading

Since the readings aren't stable at all, I'm going ahead and ordering a new set of coils and see if that does it.

Any comment is still appreciated.

 

make sure to replace your plugs too. Wires might not be necessary, but I would recommend it.

 

Plugs were checked a couple of weeks ago and were fine.

As for the wires, they visually looked good, but don't know of anyway to test them, is there any trick I should know?

Also, my coils were laying on a layer of silicone, I'm planning on going with standard CPU thermal paste for the new set, is that a good idea, as it would help the heat dissipation.

Thanks again for the inputs everyone, I should get the coils tomorrow and will install in the following days.

 

Turns out I need to get my head out of my *** when I'm checking at the cat, it was the source of all the evil. Changed the coils without much improvement. Went for a small test with the exhaust off to make sure the cat was at fault and the beast was back. I then proceeded to hollow it out and it runs back great.

Thanks to everyone who helped out, dannobre, StealthTL and fuztupnz!