Recording of Engine Knock / Rattle Noise in new CX-9: Help Needed

Mazda is generally pretty good about getting back to you. They unfortunately can't do much about their lousy dealers, other than call them directly and plead your case
 
Just curious. Has anyone with the knocking issue tried new spark plugs?

Back in the day I had a similar issue with a Honda. It only happened under load and it turned out to be a fouled spark plug.

Not yet. Will definitely pull the plugs whenever this snow melts.
 
going next week to get the car checked out. It only has a little over 5k miles, and I just changed the oil with full sythetic (Quaker State). The engine knocks right after the initial idle period (first 30 secs when car is running at about 500-1000rpm higher to warm up the engine). We'll see what the dealer says...
 
Well I took my wife's 08 CX-9 Touring in this morning for it's 20k oil change and for engine rattle!

Upon light throttle we hear an rattle/vibration coming from the engine area. It's around the middle/right side and doesn't do it if you're at speeds over 20-30+. It sounds like some type of metal bouncing and rubbing against something back and forth fast...and it's annoying.

We took it the last oil change and they said they couldn't find the sound. So this time we took it and told them about it again. They called me earlier today and said the tech cannot hear it. I told them everyone who gets in the car can hear it and I'm really surprised they can't hear it. They went back and tested it after I explained to them again not to gun it, that it's under light throttle. Well the tech found it and they said they called Mazda Tech and they are doing a TSB on it and replacing/repairing the lifters. They said it should solve the problem, but they are letting it sit on the lot for awhile to cool off and then will try it when it's cold.

I see a lot of you talking about engine knocking. Does this sound like what I'm discribing? Hopefully this will fix the problem. Fingers crossed!
 
Well I took my wife's 08 CX-9 Touring in this morning for it's 20k oil change and for engine rattle!

Upon light throttle we hear an rattle/vibration coming from the engine area. It's around the middle/right side and doesn't do it if you're at speeds over 20-30+. It sounds like some type of metal bouncing and rubbing against something back and forth fast...and it's annoying.

We took it the last oil change and they said they couldn't find the sound. So this time we took it and told them about it again. They called me earlier today and said the tech cannot hear it. I told them everyone who gets in the car can hear it and I'm really surprised they can't hear it. They went back and tested it after I explained to them again not to gun it, that it's under light throttle. Well the tech found it and they said they called Mazda Tech and they are doing a TSB on it and replacing/repairing the lifters. They said it should solve the problem, but they are letting it sit on the lot for awhile to cool off and then will try it when it's cold.

I see a lot of you talking about engine knocking. Does this sound like what I'm discribing? Hopefully this will fix the problem. Fingers crossed!

I think your problem may be similar to one described on the link on page 1 of this thread about a faulty VVT actuator. Engine knock or pinging or detonation that gte331r and a few others, including my wife's CX9, is experiencing is different. A faulty knock sensor makes sense as a possible problem, but I don't believe Mazda has figured out how to fix it yet. I'm bringing my wife's CX9 into the dealer on Monday to repair a coolant leak, and I have asked them to look into the engine knock problem. Ours is only audible when the engine is cold (not at normal operating temperature) and when accelerating harder than normal in 4th gear. We'll see how it goes.
 
just got to thinking, and I guess a quick diagnostic tool to see if the engine is knocking is what benben01 did, which is put in higher octane gasoline. If it goes away, then for sure it's premature detonation or knock. If not, then it could be something else... As far as Mazda not knowing how to fix it is another issue... But, my guess would be to retard base ignition timing a couple of degrees? I wonder how hard that is to do in the CX9. It's pretty easy on my miata. Might have to give that a try if the boys at the dealer can't figure it out.
 
Just an update with higher octane gas. I switched back to 87 on the last fill up and sure enough, only knocks when the engine is cold with load. Once engine is at full operating temp, it's ok. Switched back to 93 octane, no knocking at all. On a side note. The lifter noises I as accustomed to with a cold engine is no longer audible. Seems like the sticky actuators have worked itself out after 15K+ miles.
 
Dealer confirmed the engine is pinging/knocking under load in 4th gear. Solution recommended... Use higher octane gas. I don't need them to tell me that!! Supposedly, the problem is bad gas... whatever. But, I guess it's better to pay slightly more for premium gas than have a broke down engine.
 
At this piont I'm not overly concerned about the pinging/knocking as it only occurs when the engine is cold. Now. if switching to higher octane gasoline does not solve it, then for sure I'd be looking into this further.
 
just a followup... Put in a tank of 91octane premium gasoline and no more knocking.
 
My guess is you had a bad tank of gas. There is likely nothing wrong with your powertrain.

That's what the service adviser kept commenting on, but I doubt it. the knocking was present through a span of several months over several fillups. So, I highly doubt it was from a bad tank of gas.
 
That's what the service adviser kept commenting on, but I doubt it. the knocking was present through a span of several months over several fillups. So, I highly doubt it was from a bad tank of gas.

Sure sounds exactly like knock. Did you fill up at the same stations? (sorry have not read the entire thread).
 
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about 3 different gas stations that I frequent. It definitely was knocking, and i don't think it's the gas. It's most likely the knock sensor not working until engine warms up as mentioned in the thread somewhere.
 
Good work

gte331r
You did a great job posting and describing what went on. Beyond that you did everything that a consumer could do in order to protect yourself. I am impressed with your dedication to getting the problem solved. If no one has told you- you deserve a pat on the pack!
 
Brake booster bracket fix did the trick on mine

Hey all-

Long-time lurker, first-time posting. I just wanted to add to the knowledge base here on this thread. I have a 2008 Touring, and was also experiencing an obvious rattle sound coming from the engine compartment.

I first noticed a really subtle sound (barely perceptible) within a month or so of buying the car, back in late '08. At the time, I only heard it when in manual mode, and didn't think much of it. Since then, it's gradually gotten worse over the last year and a half. In the last 2 months it had gotten really bad--to the point where my wife was noticing it and saying, "you HAVE to get that looked at". It had become a distinct metal-on-metal knocking/rattle, and it only happened under load in the low RPM (1500-2500'ish) range. In my case, it wasn't worse when the engine was cold--in fact, it seemed like it didn't start happening until the car was actually a little warmed up, after running for 10-15 minutes. I could reproduce this 100%, every day I drove the car.

Anyway, I finally took it to my dealer (Browns Fairfax Mazda in Virginia) on Monday night. They took a look at it yesterday, confirmed the symptom, called Mazda tech support, and then learned and applied the fix for the unofficial TSB on the brake booster bracket. By yesterday evening, the car was back home with me.

End result: I'm happy to report that the issue is now completely resolved. No knocking or rattle at all anymore in my CX-9; the engine now sounds great. I wish I hadn't put this off for so long and just gotten it dealt with months ago.

-Rich

*Side note: As I understand it, the brake booster bracket fix is essentially just addressing a resonance problem. The way that bracket is installed in the factory basically can result in a metal-on-metal situation where the bracket touches the firewall. Apparently, when the engine is under load in that low RPM range, it can create a vibration/resonance condition resulting in that knocking or rattle sound. In my case, the rattle/knock really did sound like it was a much deeper engine problem, like it was maybe related to the valve timing or something like that. Fortunately it wasn't.
 
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