Loss of power & rattle, help!
 

Good evening chaps,

I'm posting from the other side of the world in the hope that you fine people can help with an engine issue on my 2004 RX-8 192.

There's a thread on the UK forum here:
http://www.rx8ownersclub.co.uk/forum...p?f=19&t=32300

Boils down to a loss of power between 6,000 to the limiter, only when hot. There's a rattle that comes with it (trying not to use the M, I, A or C words :D: )

Short video of the noise while running against the brakes in first - you will need the speakers up loud though. You can hear it most as the revs come back toward 6,000. It's much clearer in real life instead of phone-video.

http://www.youtube.com/watch?v=4ODPL1utFnM

• Plugs are new, gaps right, new coil packs, new Magnecor leads. Wired up right.
• CAT looks like brand new, have dropped it out and looked in.
• Have run Cataclean through, which helped a little but the issue quickly came back.
• Cold and hot starts are quick, never been an issue.
• I always run 97 or 99 RON fuel.
• All recalls up to date.
• SSV and VDI actuators work fine with vacuum applied and give different faults to this if disconnected.
• Ran 100ml of Redex through each rotor as a carbon remover, no change.
• Heat shields are fitted and intact, the one loose one now is held on with two stainless steel jubilee clips.
• Have tried an ecu reset as well as the 20 brake press reset, no change.
• I don't think it's water rushing/gurgling through the heater as there is a power loss accompanying it.
• MAF and IAT sensors are clean and give expected figures through the diagnostic kit.

Any help appreciated Ladies and Gents. I'm a fairly experienced DIY mechanic and I'm not afraid to pull stuff apart, I'd much rather fix it myself and spend the money on days out with my young son if possible.

Pete.

This looks like the usual broken catalyzer issue but apparently it's not your case since you stated that it is in good working conditions.
You could do a compression test for peace of mind since everything else looks in good working condition.
You could also seafoam\steam clean your engine properly to see if it changes anything before the compression test :)
Is your MAF\IAT sensor clean? You could give it a shot as well.
There may be other causes as well, internet diagnosis are tough and extremely inaccurate :)

Thanks for the reply. I have cleaned the MAF and IAT sensor, forgot to add to the list. The diagnostic tool says they're working ok, too.

CAT pic attached.

Think Seafoam is about the only thing left to try apart from a 75 mile drive to the nearest rotary specialist.

Well, the honeycomb is intact, but has anybody ever seen that much of what appears to be carbon build up? :SHOCKED: I could be wrong, so don't freak out. Let's see if other chime in.
The Seafoam might be a real good idea.
Now I need to go look at the video as the only time I've run into MIAC was on a girls auto and it would happen in the higher RPM's and then go away after the shift. I'll edit this after I see/hear the video.

This might be your best clue? "Have run Cataclean through, which helped a little but the issue quickly came back". :dunno:
Let me go find that pic of someone else's CAT I saw the other day for comparison.


Dave

Just because the face of the cat looks clean does not mean the interior/rear the catalizer is not clogged. I have seen clogged cats that look new on the face. But deeper down in they are plugged. This might not be your issue thouugh. But if you have access to a midpipe you can swap with it would be the final judgement on that possible issue.

Yo Erick........you didn't think that CAT looked a little bit(okay.... a lot) dirty?
Just curious as the pics I've seen of the insides of a good one are much cleaner.
I was going to ask the OP after a good hard drive if he has looked underneath and seen if it is glowing?????? Thoought about the mid-pipe too, but didn't suggest it.......yet.

Can you retake that video and make it longer as you run through at least 3-4 gears pushing over 6k while actually driving?

My Droid would not open the pic so I couldn't really see the pic to well. I need to buy a laptop sometime soon for when I'm away from home. But if its dirty then it's more than likely clogged. And the issue at hand. Looking at the cat after some hard driving at night to see if it's glowing is a good idea.

What if I post it this way?
See it now?

https://www.rx8club.com/attachment.p...1&d=1279490393

You know the face of the cat element is always the cleanest due to the proximity to the hot exhaust. Well when this fellow comes back on line maybe we'll have a little more info to go on.
Thanks for the pic by the way.

Thanks for the replies.

The CAT doesn't glow red after a long run. It has had the living crap caned out of it on occasion, it does get beeped every day once warmed up.

Interesting comments about the CAT being plugged further back. The towing eye looks like it had been used when I bought it from a non-Mazda forecourt, so I'm wondering if it may have been flooded and tow started at some time, damaging the CAT.

I'm on holiday in Centerparcs at the moment, I won't be able to post an acceleration run video until the weekend at the earliest.

The symptoms do seem to fit in with CAT failure, but the clean honeycomb made me think it was ok - could be wrong, I guess. I don't have a decat or spare CAT to try, unfortunately. Might see if I can get one made up locally.

How hot does your centre panel become after a spirited drive? That's another symptom about a bad cat.
The glowing usually only happens in extreme cases but after several failed CATs a common sign that I found to be a pretty reliable indicator is the tunnel's temperature :)
Hope this helps as well!

We had a similar problem,started using premix and the rattle disappeared.

bse50: The centre tunnel does get quite warm around the front cupholder sort of area, thanks for the post. The heat shields underneath are all in place too. Not having owned another RX-8 I was thinking it might be normal, but with everyone's help it's looking more and more likely that the CAT is duff.

The centre tunnel gets warm even with an healthy catalyzer, when they start to fail you start having problems putting your keys in there :)
At least that was the case on our side of the pond :)

^...............we just make toast! :)




I for one want to make sure you understand that it could be something totally different, but I'm still leaning towards the CAT.
Wish you either had a midpipe, or another CAT you could swap out with just to see. You can always take the CAT off and bang all that honeycomb out of there as others have done. But be advised that you will get a CEL(Check Engine Light) if you do this. Think you still need to confirm whether or not it glows red after taking it for a spirited run of some length.

http://www.youtube.com/watch?v=3NBJoJ6VV-I

Most noticeable after the upchange. Still getting the power loss with it.

This was after a 70 mile journey today. No glowing CAT, no red hot centre console. I was fairly moving on the journey, too.
It also started making the rattle under load up hill at 4,500 revs in higher gears today.

Full exhaust stripdown tomorrow.

Forgot to mention, the above run was with a little premix - seemed worse than before.

Took the whole of the exhaust off to check today. Managed to shine a light in through the cat from both ends by dangling a bulb on a wire, it's all intact and looks to be in good shape.
Back box appears to be all ok.
Manifold back up into engine looks ok and clean.

I think the only things I can do now are seafoam (ordered, can only get via Ebay in the uk!) and if that doesn't work a compression check. The nearest non-Mazda dealer rotary specialists are 75 miles away from me, which is a bit of a bugger.

I dont hear any rattle??

It doesn't record well on the mobile phone I'm afraid. If you turn your speakers right up you can hear it.

Guy at mazda said a really good sign of a bad motor is if at idle, it dips below 700 with the AC on... and increased vibrations... When i took mine in it was dipping to about 715 which he said he thinks bad motor...

Can anyone say if this might be detonation / pinging?

Only happens under load.

http://www.youtube.com/watch?v=i8-BlR_wPmU

I was having issues only under load, sounded like pre-det, ect... mazda did a carbon cleaning free of charge and it cleared that issue up... now im just having problems with APV, cant fix if for 6 months so for now i just read..

Thanks for your analysis! I understand this part.

Pete, very thorough first post!
You say that you checked your SSV and VDI actuators.
Did you perform a vacuum bleed down (leak) test of your vacuum actuators and accumulators?

Here's my cat pic. Replacing it with straight pipe made no noticeable difference to my power loss issue
http://img248.imageshack.us/img248/1...c01775e.th.jpg

I checked the actuators by putting a thin pipe on and sucking through. They held in place until I released the vacuum from the little tube.

I'm now wondering if I have an ignition problem. About a year ago the car lost most of its power but ran really smoothly (no rattle). I held it against the limiter for a couple of seconds seeing if it would clear, then it feels like one or more of the coils kicked back in and it took off to 8,500 revs (on a 4 port) before the power went away again. I only covered about 20 miles from there until chaging the coil packs and leads, which brought it back to proper running.

The intermittent nature of the current power loss and rattle makes me wonder if I have a coil pack, plug, plug wire or electrical connection that's not always good.

I appreciate all your assistance with this, all been very helpful.