Diagnose a noise - high pitched tone at highway speeds

"BaconSandwich is tasty." (baconsandwich) 08/04/2015 at 22:37 • Filed to: None

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I’ve noticed this several times now in my daily driver - a 2001 Honda Civic. At highway speeds, between 100 km/h and 105 km/h, I’m noticing a high pitch noise. It doesn’t sound like anything grinding/squeaking - the best I can describe it is a tone. It only seems to happen at a particular throttle position. As soon as I release the accelerator pedal, or push it down further, the noise stops. It doesn’t seem to be linked to electrical load - turning the headlights on/off makes no difference. Any ideas what this might be?

Could it be something like a fuel pump? That, or injectors is the only thing that makes any sense in my mind, given how it stops if I ease up or press down on the gas. What else is that closely linked to the accelerator pedal?

A picture of the car, for fun:

jester74 > BaconSandwich is tasty. 08/04/2015 at 22:47

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Sounds like it could be fuel pump/injector related. I'd suggest giving Seafoam or something like that a shot to clean out the system.

JGrabowMSt > BaconSandwich is tasty. 08/04/2015 at 22:48

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PCV valve is fluttering most likely. I noticed this a lot on the Neon I used to have. I’ve learned that there’s really only one way to test a PCV valve for if it’s bad or not..

Take the PCV valve off, toss it in the garbage. If it jumps back out, reinstall. If it stays in the garbage, put in a new one.

Some people suggest shaking the valve and if you can feel the spring inside vibrate, it should be fine still. Realistically, that’s really just a subjective way to test it unless you have a lot of experience with PCV valves, so I’d just see if it jumps out of the garbage or not.

Levitas > BaconSandwich is tasty. 08/04/2015 at 22:51

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Assuming its FWD, my MINI had the near opposite issue. Made noise under no throttle and full throttle, but not under some. Ended up being a blown bearing on the driveshaft, so you might take a look at those.

TheOnelectronic > BaconSandwich is tasty. 08/04/2015 at 22:57

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This is an odd one but bear with me: Our old Highlander’s radio used to pick up interference from the engine. If you accelerated the sound built with RPMs. Worth looking at, although I doubt with modern array antennas it’s an issue.

Sn210 > BaconSandwich is tasty. 08/04/2015 at 23:10

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My TL does the same at 45mph. I don’t hear it at 43 or 47, it's really odd.

Drakkon- Most Glorious and Upright Person of Genius > BaconSandwich is tasty. 08/05/2015 at 07:00

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FXT owners prefer resonate wind noises

BaconSandwich is tasty. > Drakkon- Most Glorious and Upright Person of Genius 08/05/2015 at 08:58

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That’s crazy. I’ll have to see if I notice any difference when driving into a head/tail/side wind.

BaconSandwich is tasty. > JGrabowMSt 08/05/2015 at 08:58

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Hmm, I might have to give that a shot.

BaconSandwich is tasty. > TheOnelectronic 08/05/2015 at 09:01

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I’m guessing that isn’t it - it happens whether the radio is on or not. That’s pretty entertaining though!

BaconSandwich is tasty. > jester74 08/05/2015 at 09:02

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I might have to look into that. I’m always a bit leery to use something like seafoam, though.

BaconSandwich is tasty. > Sn210 08/05/2015 at 09:03

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If you do eventually figure out what it is that does it, feel free to let me know!

BaconSandwich is tasty. > Levitas 08/05/2015 at 09:05

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The thing that makes me think it isn’t a bearing is that as soon as I lift the gas, it stops - like immediately - even before my speed changes by more than 2 or 3 km/hour.

At least I hope it isn’t a bearing...

Drakkon- Most Glorious and Upright Person of Genius > BaconSandwich is tasty. 08/05/2015 at 09:09

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My Forester noise in absolutely insufferable when it happens.

Thankfully not that often. It has to be a really strong (25+mph) cross wind

BaconSandwich is tasty. > Drakkon- Most Glorious and Upright Person of Genius 08/05/2015 at 09:17

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I happen to live in an area with frequent strong winds. Maybe that’s the reason I don't see more of them around...

oneavejoe > BaconSandwich is tasty. 08/05/2015 at 10:43

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Had a similar noise on my Z4. Only a tone or whistle at 10 to 20% throttle.

Didn’t change with speed, or load or gear. Only throttle position.

I finally got rid of it by removing the cold air intake and replacing the OEM filter box.

If you don’t have a CAI, check all air intake hoses and connections for rips, or looseness.

BaconSandwich is tasty. > oneavejoe 08/05/2015 at 11:37

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I don’t have a CAI, but I do have a stock replacement K&N filter. Perhaps I’ll pop my old paper filter back in to see if it is any different.

Gonemad > BaconSandwich is tasty. 08/14/2015 at 13:16

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GM Opalas made a whistling noise. All of them. Almost the same speed. The fastback curve would cause a low pressure region, sucking the cabin air through the gaps in the back window mounts. Opening the windows would stop the noise, holding your hands against the manual levers would also stop the noise. Pressing the windows against their seals changed the noise too. Changing speeds also worked. Aerodynamics. Check if all windows have their seals relatively intact. Any water ingestion during heavy rains?

I would suggest pulling the circuit fuse on the car stereo too.

A Ford Landau would leak the spark plug injection coil noise (whatever the translation, that thing that generates high voltages /currents to feed your spark plugs, ok?) through the radio speakers, even when turned off . Pulling the breaker would passively change the length of the circuit... tuning another frequency and isolating the radio and speakers cabling. Pretty crazy behaviour, but I witnessed it first hand. This one was fixed with a noise filter, both in the speaker lines and the radio harness feed.

The seals on the cables were less than perfect, as in “they didn’t short and blew the fuse anyway by random chance”. In those analog days, the cables would crosstalk, whether you like it or not, sometimes with unexpected behaviour. One day, we turned the radio on purpose, just to listen the spark plugs feeding that massive 5.0 V8... just like those fake noises these days. We could also hear when it was firing on 7 cylinders...