Help! - Mazdaspeed ColdAirIntake = high RPM crackle/chatter
 

Forgive me, I would have posted this in the aftermarket forum, but since this came stock on a brand new 07 rx8 (1+yrs on the lot, 10 km on the odo), and I hope to get a wider audience with the general forum than aftermarket.

For all those that got the 'performance package', or just the mazdaspeed cold air intake on it's own, I have a question for you: Do you have a very noticable crackle/chatter at 6-9 RPM in 2nd-6 gear (not 1st)? I just got the car, and after the breakin I noticed this problem. It sounds terrible, and it totally kills the fun of 6+rpm driving (I drove a leased 04 with stock intake till I bough this one to replace it)

The dealer believes it is caused by the cold air intake amplifying regular engine noise that the stock intake muffles. I know this isn't true, as youtube has several videos people posted while driving with the CAI and there are no problems. I also suspect engine damage has occurred as it sat so long on the lot, and even the service manager noticed it was not as 'peppy' as their demo '08 (I noticed this coming from my 04, but only after the breakin was done).

I know it's not cavitation in the heater core, the noise is definitely outside the vehicle and not emanating inside. I know it's coming from the CAI as its sound dynamically changes with how aggressive you drive (same behavior as CAI noise levels).

I just want to know if anyone with a cold air intake notices this chatter/crackle/ whatever you want to call it (NOT the nice smooth high pitch whine we all love to hear =).

I did try to research this with little luck, and I'm on 6+hrs of searching and coming to my wits end. No doubt someone has posted about this and I'm just blind as a bat or not using the right keywords...

Thanks! and again, sorry for putting this in general, I just know that lots of people would have gotten in as mazda gave it away free from jan-oct 07.

The "Tech Garage" section would be the best place to post this.
Don't worry about trying to get the attention of a wider audience here, you'll find MANY people in that area too who also venture to the General Discussion (basically, we are everywhere).
Best to post there just to keep threads within their own "group" and allow easier searching for future members.

THAT SAID.... a guy from our local forum experienced the same symptom and it ended up being his motor mounts.
So you might want to look into that.

Moved

Some people have experienced auxiliary port chattering at high RPM that could sound like what you're describing. It would also explain why it fluctuates with the intake noise, but it wouldn't explain why it only happens in 2nd gear... but I can't think of anything that does really. :dunno:

Jon316G, thanks for the suggestion, I have read about the motor mount issue before but never thought of that. I'll bring it up with the service manager.

rotary.enthusiast, the issue occurs in 2nd to 6th, but not really in first. It seems to get worse under heavier load (i.e. 6000-9000rpm on a flat surface in 2nd sounds not as bad as 6000-9000rpm going up a hill) in 2nd).

Thanks for the feedback, and the topic move, if anyone else has any suggestions I'm all ears!

Hi Wingman,
I've had the Mazdaspeed CAI in place for a year, about 15K miles, and nothing similar to what your hearing. I just had the factory motor mounts repalced (at 85K) with the newest version that Mazda is using now as well, so my mounts were going bad while the CAI was in place.

That said, I think the guess about the mounts by Jon316G is a good one anyway. Yours might be far worse than mine were and hence your experiencing something I wasn't.

Thanks Voodoo8, what was the problem you were experiencing?

I'm almost at the point where I want the stock filter back. I've read a number of posts from people that feel they lost power when adding the CAI, and I seem to remember my previous 8 being a bit stronger. I'll look into the motor mount issue some more and see if the dealer can check them.

btw, the car only has 2500km on it so far, I can't help but wonder if it's because it sat in a warehouse for a year+...

I had mine in for a standard misfire code that was triggered by my CAI - it picks up moisture like a sponge in heavy rainfall, car wash, or similar. Put a little load on the engine that increases air draw through the filter and - BAM - misfire. He installed it originally, I have had the filter on/off for cleanings and wanted to make sure it wasn't something I did. There wasn't. Also was getting the Mazdaspeed dual cat-back exhaust installed.

While he had it up on the lift he called to tell me the mounts were starting to look overworn. He helped me make a deal with the Mazda RM to get new mounts at no cost so I had him take care of this while it was in the shop.

I don't think the CAI makes any appreciable difference in performance on its own. With the exhaust added into the airflow stream I will say that the engine revs more freely; especially can see it during leisurely shifts (the RPMs taper off more slowly once I release the gas pedal) and the backpressure drag from the engine when allowing the engine to slow the car (versus the brakes) seems to be less. Also my gas mileage has ticked up between .5 - 1.0 MPG with the combo in place. Have not had a chance to take it someplace and go WOT to see effect on top end of the combo, CAI by itself had no effect on terminal top end when I was running it with the stock factory exhaust.

Interesting turn of events - The dealer diagnosed the problem as being the cold air intake (stock filter box = no crackle noises at all). When they went to replace it, Mazda said they stopped shipment of it as it is being redesigned. Until the redesigned unit is available, the stock filter goes back on & the current CAI comes off... I wonder if they found something new now that they've been in the field for a while...

That is interesting!
If the two bolts behind the bumper is secured tightly, I can't think of what was causing your chatter!
Thanks for coming back and letting us know!
Keep us posted!