My H3 with 21,000 miles has been having an issue with spark knock for the past month or so. At first I thought it was some rattle that occurs when I turn the A/C on. Now Im almost positive the motor is knocking and it only occurs when Im accelerating moderately/hard, usually when the A/C is on but it can happen with it off. Its occurs a lot more when the weather is really hot around 100 degrees. I thought it might have been bad fuel but Ive switched brands and bumped the octane to 89 and its still happening. Ive changed the oil, checked the air filter/coolant level, and I consistently use fuel system cleaner every 3000 miles, cleaned MAF sensor, and checked the spark plugs. The dealer checked out my rig and couldnt find anything wrong, all they did was "update" the pcm with new programming. Anyone else experience knocking?

 

I have a 2009 Alpha with 6000 miles and I thought I was going crazy until I read your post. I went to the dealer and they said it was fine. I bumped up the octane to no avail and am about to try a tankful of premium. I don't hear it on hard acceleration or slow speeds. I usually here a slight "ping" around 50 some miles an hour with light to moderate acceleration under load (like up a hill.) They did tighten my heat shields, but it didn't make a difference.

 

Just to let you guys know, I used to run 87 gas from the cheapest gas station. My brother in law who has been in the mechanical field for over 20 years and who also works at what used to be called new venture gear in syracuse, ny. Said try running premium because he heard a slight knock also, but I didn't hear anything. Ever since then I have been running premium and I have noticed that motor is quieter. Who knows if it even made a difference, but they don't make different grades of gas for nothing!!!

 

heres a video of the knocking . Its noisy but you can hear the pops and pinging under load. http://www.youtube.com/watch?v=ilXlj0wYZZ4

 

It's kind of hard to decipher all the different noises in the video, but the only one that I hear that MAY be a little strange sounds like a bad bearing in the A/C clutch. More of a rattle than a ping or knocking though.

 

no but if i focus i do get a little ticking noise from under the steering column which pisses me off

 

How would I check the A/C clutch?

 

Interesting video, but I do hear a steady hum or roar of the engine, even upon increased revs. Nothing disruptive like a ping or engine knock. I would think the pre-ignition knock would be more prevalent
under load.
I would look elsewhere for the noise you hear.
Fuel injection and variable valve timing all orchestrated by computers, our engines could run on lower octane fuel. If you use a higher octane fuel, the engine automatically adjusts to it and all octane ranges.
A side note is to use a fuel from a reputable station and company. Clean and lube the injectors and clean the fuel filter regularly.

 

I couldn't tell you how to do it yourself. I had a Monte Carlo that made a sound similar to what I THINK I may have heard in your video. The garage said that's what it was and fixed it. That's all I know. Again, it's really hard to tell from the video though, so I may be completely off base. I hope you find it though. I know how rattles and squeaks can drive a guy crazy.

 

If my engine was knocking would it be constantly making knocking and pinging noises? My "pinging" is really inconsistent, usually only makes the noise a second or two but sometimes uphill it would keep making the noise. Usually hot weather and A/C seems to do the trick for the motor to keep making the noise.