I have a 2005 RX-8, I have recently installed a HKS suction intake and a HKS Legamax exhaust. It definately has more power and torque but as I accelerate above 7500 rpm it makes a really bad noise from the intake and it seems as though past 8000 rpm the motor is not doing anything although the tach is still climbing to the redline. If anyone out there has any advice on why this is happening I would appreciate knowing before I return to the place where I bought it. I would probably benefit having some knowledge when they give me there reason. Thanks, Paul

 

HKS racing suction is one of the loudest. Do yo u drive an AT? That may be why the engine does nothing after 8k....

 

Welcome to the addiction!!


If you're car is NOT manual then obviously you'll bottom out after 7500...


If you're driving manual, a few questions:

1.) Is your vehicle 2nd hand (recently purchased)? How many km are on it?
2.) Did you notice abnormal when going past 7500? (e.g. knocking sounds, the engine 'dying out'.. etc)
3.) When was the last time you changed your coils / spark plugs?
4.) Is your ignition system OEM? Aftermarket?
5.) Did you install an AP with an economy flash?


Did you notice the problem before changing the intake/exhaust? Also, did you perform a reset after switching your aftermarket components?

 

^that

and welcome to the addiction

 

WTF? A healthy manual rx8 will have power past 8000rpm. Its peak hp is at 8500rpm...

 

Hi and thanks for the replies. I have had the car for two years, bought it with 36 km. Before the additions it was smooth right to the redline and this is the reason for my concern. It definately gets there quicker now but the noise just doesn't sound right. There is no knocking or dying out, it just seems flat. Plugs were changed about 16 km ago but it has been flooded once since then and it does has a bit of a flutter at idle. The ignition is OEM and I haven't performed a reset after installing. I put the intake on first and that is when the noise first made an appearance. I thought that maybe the stock exhaust was restricting the new rush of extra air and thought that I would wait until the exhaust was in and installed before persueing the problem any farther. It is a six-speed.

Thanks for the welcome and the help, I am going out for the rest of the day so I will look to see if there is anything further tomorrow. Once again, thanks for the help and it really is an addiction.

 

yeah its your coils...flutters at idle, is a definite sign

 

I just ordered coils plugs and wires for $311shipped from one of the vendors on the forum. The plugs alone where over $300 from a mazda dealer and that was with an employee discount.

 

How often do wires go anyhow?

 

I havent changed my Coils/Wires Since I bought the car back in 05, I have changed my Spark Plugs once, and thats because the dealer did it free because of a recall. Is this bad? My car runs great...Im at 63k mi.

 

zumn...ur lucky ur coils havent gone out, me too, im sitting at 53k and my coils are just starting to go out

 

i'm pretty sure he means automatic LOl

 

heh... yes I meant automatic...


To the OP:

Try the reset first, if you're sure the problem started AFTER you installed the custom intake/exhaust.... for some odd reason the RX8 doesn't like switching its intake...

If resetting doesn't solve the problem, I'd check over the coils and ignition... and maybe even the injectors...
(That's based on the hypothesis that your car is OK at low revs, and only starts getting the hiccups @ 7500+)...

 

Thanks everyone, I will try the reset first if that doesn,t work I guess that next step will be coils & plugs.

 

If the reset doesn't work, I'd suggest that you take RX8 to a mechanic (rotary specialist if possible) to check it out first.

Just in case the problem isn't with the plugs, since it's harder to pinpoint the problem just through the forums.

If the problem does lie with the spark plugs / coils, then I'd also suggest reading on the aftermarket solutions. Apparently the RX8 doesn't exactly have the best OEM ignition system...

Good Luck getting the car fixed

 

Can you describe the sound in details? Cause I think I'm having the same problem with you as well after installing my HKS intake

Once my 8 reached 6500 - 7000 rpm at 4th gear...the weird noise starts and it is like a losen screw (which is not cause everything is lock tight) rattling inside the tube.

I don't have the time to check everything yet..but I think I did a bad job on the foam paddings between the tube and the heat shield box. Not sure if this cause the sound though....

 

Back again, I took the advise offered about the reflash. Looked into it, seeems I need a Cobb tuner in order to get the problem solved. That and a dyno set-up. Anyone know where to get a Cobb tuner. Thanks.

 

i'd really look into coils plugs wires before the cobb replacing the coils plugs wires often is a good idea this is the second time ive replaced mine. the first time i replaced them i thought my engine was running fine and normal but it made a noticeable difference. then i just replaced them last week and thought my engine once again was running top notch but yet again was surprised how much power i was down. i replaced my coils plugs wires at 80 000km and at 130 000km

 

this sound you guys are talking about.. does it sound like flapping?

I have an 06 6AT with 36,000 km, and after adding a free flowing intake we now hear this sound in 2nd gear and up after 5500 rpm.

It's not the MIAC noise everyone talks about, thats forsure.

We run 94 octane in the car at all times, so it is not detonation either.

It sounds like there is a flapper opening and closing in the intake, and maybe a little loss in power. It is an odd sound, and seems to get worse with heat.

Could this be coils/ plugs and wires as everyone is suggesting?

 

most likely, I'm getting that now too and I took mine to the dealership a week or two ago and they said the plugs + coils + ignition wires are dying, I'm not going to switch out everything all at once, as we doubt EVERYTHING is dying, but definitely a good start is to check those first.

 

If you're going to spend money on coils, consider the BHR Ignition kit.

Spend slightly more than OEM coils and get something that will last you wayyyyy longer (not to mention a lot more reliable).

 

I'm looking into a set of BHRs....its the only way to go...
________
ROLL BLUNTS

 

Welcome to the clan!

 

Sorry, I don't mean to threadjack.. Check out our sound.. We video'd it.

https://www.rx8club.com/series-i-trouble-shooting-95/flapping-growling-yarrr-engine-mature-semi-educated-post-lol-198440/

Still think it's ignition coils plugs and wires?

If it is, what I think we may do is order coils and wires from Lordco.. if it fixes the problem, send them back and order the BHR kit.