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

I have experienced an on-going problem with our 2008 CX-9 and could use some help.

Basically we hear an engine knock / rattle noise when the engine is under load. It developed at about 9,500 miles and occurs in two scenarios:

1. When driving up a hill leaving our neighborhood in the morning (see attached recording)
2. When trying to accelerate when cresting very small hills

In scenario 1 above, we hear it for a sustained period of time (~ 30 seconds continous).

In scenario 2 above, it only occurs for about a second or two and is much less noticeable.

I have taken it to our dealership three times with no luck in fixing the problem. On the last trip, the dealership kept it for about a week and a half and concluded they could not hear the problem. They told me they had Mazda reps drive in and could not hear it either. Overall, communication to me was very poor, but that is another story for another day. I told them I would record the noise.

So now I have the entire thing on tape, as well as a very good recording using a USB microphone fixed under the hood. For those that are interested and think they can help, I am going to try to attach the microphone recording to this message. In an effort to reduce file size, I have reduced the recording to only the event itself, which occurs as I am driving up the hill noted in item 1 above (less than a mile from my house). The file is about 500K in size, so I am hopeful I can attach to this posting for others to listen.

My problem is that after three attempts, nothing has been done by my local dealership to fix the problem. They are unwilling to take any action on the vehicle after I brought it in for the third time (the first time they rerouted the brake booster connect, the second time they uploaded new codes to the cpu, and the third time they said they couldn't hear anything and did no action).

I contacted Mazda Corporate through their 800 number earlier this week, but I have not heard anything from them since that time. They did mention they would call me to coordinate sending some folks out here to ride in the car. They said to not contact the dealer and to wait for them. I told them I had a perfect recording and video and happy to share to help them diagnose the problem, but again, I haven't heard anything yet.

As for the vehicle, it is a 2008 CX-9 with ~10,000 miles on it. After you hear the recording, you will understand my concern! (noise starts at about 12 seconds into the attached file, then gets really loud... at the end of the hill, I engage the throttle several times to show the noise is coupled to the application of the throttle). My family has not driven the vehicle in a couple of weeks, and it is just sitting in my garage waiting for action to be taken by Mazda.

My questions are:

What to do next?
Does Mazda back their vehicles and support their customers?
Any ideas on what the noise could be?
Anyone else with this noise?

I have never dealt with Mazda before at this level. I do have a 1998 B4000 Mazda pick-up with over 160,000 miles on it, and it is an outstanding vehicle with no problems whatsoever. I also owned a 1987 Mazda B2300 pick-up with over 115,000 miles on it prior to selling it, and again, no problems. Those experiences factored in strongly in purchasing a CX-9 over Honda Pilot or Toyota Highlander, but now my wife and are becoming very concerned given this noise! While we love the CX-9 design and feel, this engine noise at such low mileage is very, very concerning. Again, we have never dealt with Mazda at this level before. We also own a Honda Accord with over 110,000 miles on it, and we did have to deal with Honda on a transmission issue at about 25,000 miles, but they were outstanding, and it was a tremendous, positive experience. The car has been great ever since, and that is over 85,000 miles on it later!

It is upsetting when your 160,000 1998 Mazda B4000 and 110,000 mile 2001 4 Cylinder Honda Accord vehicles sound MUCH better than your new family vehicle (2008 CX-9; V6) with only 10,000 miles on it.

Any and all help/adice is GREATLY appreciated.

Wow, that did not sound good. There are a couple of posts in the forum dealing with engine knocks specifically in the 2008. I think one of them was an actual TSB about an engine knock while climbing hills. The other one had something to do with a failed VVT actuator. I've put a link to the post below. I'm gonna take a guess and say they've probably taken care of the first issue as it was an ECU reprogram that fixed the knock while climbing hills. Sorry to hear you're having problems and maybe the post will help point you/them in the right direction.

http://www.mazdas247.com/forum/showthread.php?t=123726783&highlight=engine+knock

Pick a Mazda independent dealer not the Ford/Mazda combo. In general, the master technician there only needs to focus on Mazdas and more specialized in Mazdas.
My nearby dealer provides a Mazda loaner for repair works and major service. I know no Honda/Toyota do that in my city.

Thanks to all for your comments.

Vikefan7: You are correct. The second time I took it in to the dealership they did the TSB on the program. Unfortunately it didn't fix the problem.

Ceric: Thanks for the note, but unfortuantely I have been taking it to a Mazda independent dealership.

CX9 SportOwner: I did hear back from Mazda corporate today. They have scheduled a regional technical specialist to come to my house on Tuesday. In the meantime, I have provided him with the recording of the engine knock / rattle.

I will keep everyone updated on the progress. Again, thank you for taking the time to comment.

gte331r said:

Thanks to all for your comments.

Vikefan7: You are correct. The second time I took it in to the dealership they did the TSB on the program. Unfortunately it didn't fix the problem.

Ceric: Thanks for the note, but unfortuantely I have been taking it to a Mazda independent dealership.

CX9 SportOwner: I did hear back from Mazda corporate today. They have scheduled a regional technical specialist to come to my house on Tuesday. In the meantime, I have provided him with the recording of the engine knock / rattle.

I will keep everyone updated on the progress. Again, thank you for taking the time to comment.

Click to expand...

I will be interested to hear what they say I have had the same issue, but mine is not quite as bad as yours.

That recording was great. Is there a way for you to isolate which bank the knocking is coming from? Maybe place the mic on both banks and take some recordings of each bank. Also, did you notice any check engine lights while it was knocking? Rough idle, etc???

If that's the case, you should definitely get a CEL. Wondering if it's something really simple like a faulty knock or cam angle sensor.

benben01: Thanks for the comments.

As for your questions, we have never noticed any check engine lights. As for the idle, it is always smooth, regardless if the car is cold or warm. The full/entire recording and video show that perfectly as I record from the turn of the ignition switch of the vehicle. The noise only occurs when the engine is under load, and only under load in the two particular circumstances noted in my original post.

As for microphone placement, I haven't tried placing the USB mic in a different location. In the attached recording, it is in the upper left corner of the engine compartment if facing the engine after opening the hood. I will try to place it on top of the battery in the the upper/mid right of the engine compartment as a comparison.

CX9SportOwner: Thanks for carefully listening to the recording and chiming in with some thoughts.

VVT mechanism is more complex (than regular DOHC) and often creates some problems at the early phase of engine (such as that of our CX9). The original 3.5L from Ford did not have VVT. It was later enhanced.
The VVT on BMW also caused some issues (E46 inline-6) in early days.
So, I won't be surprised that VVT is the culprit.
There are sensors on cam position/angels. Codes would have been thrown out.
So are misfiring of any cylinders. However, valve lifting (sticky or not) is not monitored. I am not sure if the Mazda/Ford has any monitoring sensors on the VVT mechanism. We will see.

gte331r,
You should keep a record of all your interactions with the dealer. Just in case that you might need to file under lemon law for another CX9 should they fail to fix it three times on the same issue. Hint it to them that this is an option on your mind. That would get your dealer seriously working hard for you. (now that you have proof that the issue does exist!)

Good luck.

The Mazda regional technical specialist came to my house on Tuesday and rode up the hill with me. I used the same setup (video camera inside vehicle + USB Microphone underhood), and we got another clear recording of the engine knock (multiple occurances). He is now comfortable with the problem and is working with Mazda engineering for a solution. He is going to coordinate a trip back to my house with a Mazda engineer to try resolve the issue with my vehicle.

As for the problem, here is a preliminary diagnosis for those that think they may have experienced similar problems:

Turns out the CX-9 has a knock sensor, which is not uncommon in modern engines. However, and based on my understanding, the knock sensor in the CX-9 doesn't activate until the engine is warm. So there is potentially an operation window by which the CX-9 runs without the benefit of a knock sensor controlling the engine knock (window of time being from the moment the vehicle is started until the time the thermostat opens and the operating temperature is reached, denoted by a reading halfway between the C and H on your temperature gage).

If your engine has the same problem as mine and driving on level terrain while the engine is cold, you probably won't notice a problem; however, when the engine is under load, like when going up a hill (can even be a relatively slight hill) and if the engine is cold and has the same problem as mine, there is an opporutnity to hear engine knock. In my case, since my engine is cold when going up a sustained hill, the engine knocks substantially (listen to the recording on my original post above). Once the engine is warm (i.e. turning around and driving up the same hill again once the thermostat is open), the noise is less noticeable as the knock sensor is activated and trying to do its job to reduce engine knock.

As for the second observed failure mechanism (i.e. the brief engine knock noticed when cresting small hills, regardless if warm or not), that could be by design. For better engine efficiency and more power, some vehicles are designed to operate near the detonation limit (limit at which engine knock occurs). Only Mazda knows how much they pushed that limit for the CX-9. If the engine is warm, and in the case of my CX-9, this results in periodic knock throughout any routine drive when under load as the knock sensor kicks in and adjusts (retards) the spark timing slightly to supress / eliminate the engine knock. I found this very surprising. The USB microphone really tells the tale, as there were multilple instances the microphone picked up on engine knock that lasted about a second or two well after the vehicle was warm, just to have the knock go away due to the function / operation of the knock sensor. Again, I was surprised how often the USB microphone picked up on the knock after the engine was warm -- many more instances than I could hear / detect when inside the vehicle driving; however, I was able to detect a few of them, as supported by my verbal acknowledgement of the engine knock recorded on film while driving the vehicle, which coordinated very well with the clear instances of engine knock recorded by the USB microphone. Naturally all of these instances occured when the vehicle was under load.

The problem with engine knock is that it represents abnormal combustion, which can lead to problems ranging from loss of power to a reduction in engine life. For those that are interested, I thought this article explained engine knock and knock sensors fairly well:

http://www2.zhome.com:81/ZCMnL/PICS/detonation/detonation.html

That is the latest. I will keep everyone updated on my progress.

CX-9 SportOwner: Thanks for chiming in. In response to your question -- it's neither at this point.

It's not normal but virtue of the recording. There is no scenario by which a car should make that noise / engine knock going up a hill (whether cold or warm), and Mazda acknowledges that and is trying to fix the problem. Other vehicles we own are much older and have no problem whatsoever going up the hill. As for the intermittent engine knock once warm and under load, the initial inidication was that they consider it "normal" and the knock sensor was performing as designed; however, diagnositics will need to be performed prior to reaching a final conclusion.

The exact solution to remedy the problem when the engine is cold is TBD at this point. Ultimately the visit by the regional technical specialist resulted in him confirming the problem and understanding exactly when the vehicle experiences the engine knock. He did bring some equipment with him to help diagnose a solution, but unfortunately he was experiencing difficulties with his laptop and was unable to implement any of the equipment for diagnostics.

So as for a path forward, the technician and engineer need to coordinate a visit and work with the vehicle for a couple of days to remedy a solution.

As for the knock sensor itself, it is my understanding that they consider it to be fine, and it is operating as designed (i.e. not working unless the vehicle is warm).

I am curious if a brand new CX-9 driven up the hill when cold exhibits the same problem. Actually, the technical specialist made such a request to my local dealer to go ahead and drop off a new CX-9 at my house the night before so we could use it as a comparison / reference. Unfortunately my dealer said he didn't have the personnel or resources to drop off a car (14 mile round trip from my house to the dealership). Once again, great customer service by the dealership.

Thus far my experience with Mazda corporate has been very positive. Hopefully it will continue on this path. They called when they said they were going to call and the visit by the regional technical specialist was on-time, positive, and professional. The plans to coordinate with an engineer from corporate to inspect the vehicle are also appreciated. However, my experience with my dealership on the other hand has been terrible. They have been unsupportive and unresponsive.

I did meet with a lawyer today and am considering additional options as a back-up plan. Other than the engine knock, we do love our CX-9; however, the engine knock is concerning. If Mazda is able to fix the vehicle, that would be great. However, if they are unsuccessful, unwilling to remedy the situation, and considering it is a ~$35,000 vehicle, I do want to protect my family. Unfortunately my very poor experience with my local dealership has put me on the defensive and in an entirely different mode (as evident by my documented recordings, which I didn't pursue until after the third time taking to my local dealership with an unsuccessful repair -- or actually, no action taken on the third time despite keeping the vehicle for 10 days).

As an owner of three Mazdas over the course of 20 years, Mazda corporate is responding as I would hope for a company that has made very solid, reliable products for my family. As mentioned in a previous post, the other two Mazdas each had over 100,000 miles on them and were very good vehicles. In fact so good, I never had to bring the vehicles in and experience these sort of interactions with service (if you can call it that) at a terrible dealership!

I believe the noise I posted about a couple of weeks ago is the same one you are experiencing. Your recording helped a lot, and it sounds different in the engine compartment than inside the cabin with AC and music on.

The noise is weird, even at high cruising speed, pressing on the accelerator will induce the noise, letting off the gas will take it away.

I haven't been worried about it as I drive the CX-9 around 1,000 miles a week without problems. In fact, this is probably one of the best cars I have ever owned...and I have owned lots of cars!

I'm looking forward to hearing what the ultimate causes of this noise are and even more looking forward to the resolution.

Thanks for all of your work, gte331r!

Hi

I am in OZ. Would you mind indicating where in the states you are from and what component of Corporate Mazda you are dealing with.

gte331r:

I have a 2009 CX9 Sport AWD with 8,000 miles.

Just recently it has developed the same sort of knocking problem you describe. Every morning I take my son to school which means driving a long gradual grade at 35 MPH. As soon as the RPMs settle down and the car begins to cruise pulling the hill a light knocking starts, similar to that in your recording. The engine of course is cold and hasn't reached operating temperature. But it seems to be getting worse and now sometimes happens even when the engine is warm. Driving on flat roadway everything sounds fine as well as pushing it on steeper hills at higher revs.

I've tried putting 89 in it just as a test and it still has the knocking problem. Of course, a CX9 with 8,000 miles should run on 87 and it shouldn't knock. Mine didn't knock when new.

The last post on this thread was from April and you were still in contact with Mazda about it. Did you ever get a resolution for your problem?

Thanks!

I made a recording of driving up the incline this morning by putting my cell phone in the engine compartment above the battery. This was with the engine cold, but it happens warm too, just not as much.

Any ideas appreciated
Thanks

I thought I was getting paranoid, but I experienced the same problem a couple of weeks ago going up the hill coming of out my neighborhood with a cold engine. I only noticed the noise with the windows down and the parked cars along side the of the road. I back off the throttle immediately. The other times I noticed the slight knock is with stop and go inside the parking garage at work. It would knock for a split second when I accelerate from a stop and then goes away. The only car I had that did this was our 2007 Honda Odyssey. Never got to the root cause with the Honda before it was traded in. FYI, I have 12K on the 9 now.

benben01: your description sounds like the same issue I have.

I'm taking our much loved CX9 to the service department at Ron Tonkin Mazda in Portland, OR on Wednesday to see what can be done about it.

If anybody has had this problem and has had a dealer resolve it, please let me know the details and the name of the service guy at your dealership.

Thanks

So some of the service technicians are saying that this is "by design"?
That is B.S. to me. No knocking is by design.
Mine does not seem to show such problem. (maybe not so serious so I have not noticed it)

There is a pretty steep grade within 1 mile of where I live. I should try it when my CX9 is cold.
Did you guys tape a sound recorder under the hood?

Not sure about you guys, but if I wake-up real early in the morning [4:00am] and try walking/jogging up a step incline, I might hear some knocking or clicking. lol

Since Houston is void of hills, going to be a tough test for me, unless I happen to find an Interstate entry ramp that is going way up. What are you guys defining as "cold - not-warmed-up"? Is this in minutes, miles or temp gauge reading?

Also, what is the boards general opinion of how many miles it takes to fully break-in the CX9. Mine has approx 3100 miles...

Thanks and I hope you guys find resolution to your problems. I also concur with Ceric that knocking of any type is absolutely not by design.

PS - I believe you guys should be commended for going the extra mile to provide Mazda and its dealers such accurate and non-refutable evidence. This both cuts to the chase and gives them the data they need to effectively troubleshoot the problem(s), which is good for everyone in the long run - kudo's!

Regards,
tstex

I taped my Windows Mobile cell phone on top of the battery and hit record on the voice recorder program. Since the engine was cold I didn't worry about heat and the phone.

Here in the Cascade Mountains just about everything is on a hill. But for my issue you don't have floor it rocketing up Mount Hood--just the opposite. The problem seems to be most pronounced when the speed is low (25-35 MPH), the hill is moderate, and the foot is light on the accelerator cruising with RPMs < 2000 in 4th or so.