Stealth HHR

WOndering if anyone else has the same issue I have noticed. When my engine is under low rpms it sound what I call "noisy or Chattery". This happens in all gears especially noticeable when on highway and give a little more gas before the boost comes up. Any suggestions would be helpful. Thanks.

aradmahogany

I THINK our ecotecs (no matter displacement because the black is the same between 2.0 2.2 and 2.4) all are somewhat audible to a certain extent. At least mine has been that way since I can remember. I really only notice mine when a idle and with all the windows up though..... Maybe try to record the noise? might be lifters or something if it "chatters."

Kersh

Just to clarify, are you getting the noise before the boost builds, or before the RPM's increase? (does the noise disappear when you tip-in for add'l power, or after the RPM's increase BECAUSE you've hit the gas for add'l power)

I ask because if the noise goes away with changes in boost and/or engine timing, you could be getting Pre-ignition knock.

If it's strictly RPM related, it could be a timing chain tensioner issue.

If it's knock, your PCM should be eliminating that by retarding engine timing. I see you have a superchips tune. Are you running premium at all times? I know the factory (stock) programming can compensate for regular fuel, but any of the aftermarket upgrades REQUIRE premium fuel of 91 (or better) octane.

Any SES codes?

Stealth HHR

I can already dismiss the Chain tensioner since I replaced everything timing related except the valve timing gears at the end of the cams. All was done to spec and noise did not change before or after. sound did not change before tune or after. Boost eliminates the sound once it builds and RPMs build. This is mostly at low RPMs It is most annoying in 5th gear on the highway at 55 mph. If i give it gas and there is no boost yet the engine sounds noisy like valves slapping or something like that. It is not evident at idle or under boost only as I described. Don't know that a recording would work since it is noticeable to me since I drive daily, but I have owned many cars and this is the first that sounds like this.

Stealth HHR

I also run only Premium fuel and there are no codes.

DrLoch

It could be valves slapping or a valve train noise. Some of the earlier LNF's, 08/09, were known to have issues with the rockers and the lifters especially if you had extended the RPM range. I.E bumped the rev limiter up. Only way to know is to remove the valve cover and look. If you're going to do that check the exhaust side first.

Here's a link to the CSS bad rocker arm/lifter questions - Cobalt SS Network

Stealth HHR

I'm uploading a video to YouTube. Hope that helps

Stealth HHR

Hopefully a good ear can hear what I'm talking about.

Kersh

I tried a really good set of headphones, but am not discerning the sound you're describing.

It was hard to hear sideways (sorry, had to say it...)


Another idea...Busted catalytic converter brick?

Low throttle the brick bounces around and creates noise, but add'l air flow holds it in place and stops the rattling...

Dbeluscak

I tried with headphones as well. Sounds like a the timing rattle. But if you've eliminated that possibility I think Kersh might be on the right track. I have strapped my cellphone to the valve cover for engine troubleshooting. Not exactly a good idea, but I can't see under hood the while driving.

Do you have a stock downpipe? Didn't see one in your sig.