It does it when I'm cruising at a steady speed. Soon as I let off or accelerate it stops immediately as if I pushed a button. Sounds like an electronic noise coming from a speaker almost. Weird.

 

Anybody?

 

Owl in the engine compartment.

There could be an issue with air leaks in the engine air intake system ducting or air cleaner. Has happened the air cleaner cover was not installed correctly and caused this noise. Also check the intake air ducting for leaks. The sound maybe air being drawn into the engine from areas it should not be.

 

I cannot locate the owl! Sounds to be coming from brake booster area. Now I can make long steady hoots with 1,300 RPM. My power breaks stop working, btw. I've had a stuck caliper piston .... These cars can do without power brakes, just fine! Oh... Check out that oiil leak lol! Synthetic! Now I'm using semi-synthetic! Still running like new, though! 243K miles.
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If a 2000 4 cylinder check for oil leakage from the oil pump drive shaft seal. Look on the firewall side of the front timing belt cover and under the side bulge of the cover for oil leakage. This is best done with the passenger tire removed. If an oil pump seal it will only leak with engine running. If so check oil FREQUENTLY as the engine can drip a quart in 30 miles.

Find the vacuum hose that runs from the brake booster to the engine. Disconnect it and plug where it attaches to the engine. Start engine and check for noise.

 

First, toyomoho, thank you for all you're help! Although I wasn't able to duplicate the noise, just the normal change in RPM, these new trouble codes could possibly be related and escalating due to my ignoring it. Last night, accelerating from a stop, an immediate misfire occurred - Not intermittent. Immediately pulled codes, as you can see yesterday's and todays results. Today it felt as if another cylinder was misfiring! According to the new scan, that could be. Notice all the evap codes..

New spec plugs and used plug wires from donor car 6 months ago. I go through 2 to 3 quarts of oil DAILY, occasionally spilling oil onto and around the reservoir where #2 cylinder is. What's your bet, toyo? 1/2 cylinder are both on one coil pack! (please let this be the coil?!) In the meantime, I think I should swap coils and clearCEL ?

 

it's a cracked wire harness at the oil plug or leaking coil.

 

it's a cracked wire harness at the plug harness at coil OR crack on coil.. most likely bad wire. seen it arcing there.

 

Operate the engine at night and look for that arcing. A cracked coil can cause your issues including the noise and perhaps even noise from radio. Try AM to determine if greater noise.

 

I think I hold the record for the Hottest coolant temperature level / Highest needle mark! 😂

Forgot to check the coolant level! But I should of installed the new Toyota radiator I found at pick-a-part! instead, I epoxied the crack on top of radiator=(

Was doing a good 95 mph up a grade on the highway and noticed a strange cloud of smoke far behind me that I've never seen before 😆. Looked down and seen this:

Talk about being too late! Immediately shut off the motor and coasted to a stop at an exit. Smoke was billowing from the rear head! Couldn't get it started and killed the battery. Slept overnight in the car and got lucky finding a 04 Impala for 1100 on craigslist with 170k miies but is in perfect mechanical shape and drives like a 10,000 mile one! I'm astonished how this can be, especially a Chevy! Probably all freeway miles.

Brought a battery to try and get the Camry started the following day and killed that battery and finally got it started to drive home 50 miles away. Motor ran alright but l, forgot to bring water and quicky began running hot. Drove to next exit for water at gas station shut off the motor without any thought and never was able to get it started after trying for several hours. water on the plugs.
Cleaned them up with starting fluid down the intake. Almost had it going but couldn't get past the one putt run cycle and the tired out the starter. LKQ gave 370$.