I have a 2005 rx8 with around 111,000 miles and it runs great, starts decently, pulls hard and sounds very clean untill I drive it for around 15-20 mins then it loses throttle response badly along with its acceleration and when you lay into it it makes a raspy rattling noise.. Just pulled out the ssv and cleaned that but it didn't change the problem at all .. Any ideas??? I made a video of it in action also the first clip is when it's cool yet and how it should sound (does have a cold air intake so most of the sound is coming from that)

 

Anyone??

 

How about more info on the car, when was ignition replaced? How much gas was in the tank? fuel pump life?

 

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I am assuming it is the catalytic converter
Get that checked. It is probably overheating.

 

The gauge doesn't show any overheating and the noise sounds like straight from the motor itself.. But how do I check the cat?

 

It does it anytime full or empty tank just as soon as it gets to normal temps.. I havnt replaced anything ignition wise yet but I've been looking into it.. Wanted to get some input before I blow 300$+ on all new coils,wires, and plugs

 

To pull the cat, get the car up on stands, disconnect the O2 sensor, unbolt the cross member, unbolt cat. Install in reverse order.

 

drop the cat and check that it isn't clogging or broken and don't "consider" changing out the ignition components if it hasn't been changed for more than 30k miles or more you "should" change it out

 

Another thing to consider is the Vacuum solenoids on the upper intake manifold, these can work just fine when theyre cool and then wont work when hot. replacemnets from mazda are $75 each but there are lots of engines out there waiting to be parted out and you could pick up some good used ones cheap.

When you go to test them, try it with them at room temp and then run a hair dryer over them for a bit until theyre "under hood" warm and test them again.

I had this problem and didnt discover it until after I had pulled my cat and inspected it to be ok. The car would be fine for about 5-6 minutes and then it would start hiccupping like this, I thought it was cat, fuel pressure whatever. Turned out to be vacuum solenoids, who knew

 

I'm in the middle of my cool,wires and plug installment right now .. Took the cat off the other day it had a crack threw the first set of honnycomb filter things so I gutted it and put it back on and now for some reason it won't even start now???...if it don't work I'll have to look into that thanks

 

Update: replaced coils,wires, plugs , and gutted my cat still same problem ??

 

When you say still same problem, is this the won't start problem from your previous post or the original loss of power and raspy sound issue? There are a lot of things that will cause a loss of power in an 8 and it looks like you are on the right track. I agree with Nathan's suggestion about the vacuum solenoids.

 

Sorry yea I got it started (was flooded) I guess I'll try the solenoids next lol.. It doesnt lose power untill it's been running for like 20 mins or so then it makes that nasty noise sounds kinda like a rattle and then the power is not there

 

My car is making the same noise. Thought it was compression related but it's intermittent.

Any updates? Did you check your vacuum solenoids?

 

I just got my new vacuum solenoid in the mail I'll be putting it on here soon and let you no

 

Sounds good. I just drove mine again and the sound cuts off entirely over 7000 rpm, which to me seems like either the VDI valve is stuck open or the VDI solenoid valve is stuck open, causing the VDI to remain open.

I was too scared to go over that before because it got louder, but then at over 7000 rpm the intake is in the right configuration, so no noise.

 

Put that vacuum solenoid on last night and there has been no change I took it above 7k and it still had that nasty rattling noise also... I'm not sure what you mean by vdi if it's the same as your ssv valve I took my mind out and cleaned it cause I thought it was sticking open and that didn't change it either...

 

To anyone having this issue, any engine codes? I have a 2004 with 70k or so miles on the engine that's behaving exactly as in the video. It's thrown codes P0410, P2004, P2009, and P2016 all having to do with the APV being stuck open and/or having a low circuit, so if the OP is still having this issue the APV may be worth checking.

My biggest suspicion is that possibly the APV has a considerable amount of carbon built up and once temperature rises enough that causes it to seize at whatever position it's at. I decided to premix and run the car really hard during a 3-hour drive I had in order to try and break loose some carbon and for the time being it seems like that solved the issue for me. After doing that it appears to have better throttle response in every gear as well.