Knock Sensor Fun!

[TexasDave]

Wife was driving her 2007 Camry LE (4-banger) to work, and called me to say it didn’t have enough power to get out of its own way. Would accelerate fine to about 20 MPH, then CREEP up to about 40, then do OK up to freeway speeds.

Drove it home that evening, and of course I needed to check it out. Sure enough, BIG dead spot in power between about 20 and 40. Pretty anemic after that too.

Car had about 50K miles on it. I didn’t have an OBDII reader at the time, so I decided to troubleshoot it the old-fashioned way. Figuring it might be a bad spark plug, I pulled the connector off one coil at a time to see if it had a dead plug. Nope, each time it ran rough. So I resorted to driving to the nearest Auto Zone for a free diagnosis. Their printout had FIVE faults – one for each plug, and one for the knock sensor. So I bought new plugs and headed home. (OK, those of you that are rolling on the floor laughing, I know, I know, but I’m an old guy – gimme a break!)

Put in the new plugs, and road-tested it. No change. Bummer. So I headed to the internet to see what I could find about a knock sensor. Several hours of searching found a service manual. Diagram of the knock sensor location was strange. Looked over, under, and around the engine. No knock sensor.
Hmmm. So I resorted to the knock sensor replacement instructions.

Step one: Remove the windshield wipers. Hello????

Turns out the knock sensor is on the back side of the block, under the intake plenum. So you have to disassemble the body parts at the back of the engine compartment to get room to work. Really not a big deal, but interesting. Then you play contortionist and work in a mirror to take the bolts out of the plenum, wiggle it loose, and VIOLA! You find the mouse nest between the plenum and block (warm in there!) and the (tasty?) wires that the little sucker ate in two. A little creative wire repair, several hours of re-assembly, and the Camry is its old peppy self.

Turns out the ECM advances the timing until the knock sensor picks up pinging/knocking, then backs off until it quits. If the signal from the sensor is gone, it retards the timing all the way to avoid damage. No power at all, but it runs.

SOooooo, if you have no power and are setting the knock sensor code, and it’s winter, you might just have a critter nest in your engine. (Took one out atop the cabin air filter too!)

And oh yeah: If you pull the plug wires with the engine running, it will set an error code for each one.. DUUUUHHHHH! Runs nice with the new plugs though...

Are we having fun yet??

[Tech1984]

Other areas I have seen on gen 6, throttle body connector wires, crank sensor wires, and the engine ground wires near that knock sensor you were talking about.
I have plenty of engine wiring harnesses here (P#82121-06751) as trophys.
BTW, insurance company's don't hesitate to cut a check for this repair. It's that common!

[arabianobsession]

^Are you serious!? That's funny, and pathetic, at the same time.

[Tech1984]

Somebody told me once, (and you can take it as you will), that mice are attracted to the insulation on the wires, ON JAPANESE CARS ONLY!!
Something about them are tasty to the little critters. Hard to believe? YES!
But now that I've seen so many.....kinda makes me wonder.

[11LE]

Props for being capable of working on your car. I know people who bring their car to the dealer for simply windshield wipers.

[arabianobsession]

^Or to put air in their tires.....yikes.

[Glenn8963]

Originally Posted by Tech1984

Somebody told me once, (and you can take it as you will), that mice are attracted to the insulation on the wires, ON JAPANESE CARS ONLY!!
Something about them are tasty to the little critters. Hard to believe? YES!
But now that I've seen so many.....kinda makes me wonder.

it is not just japanese cars..ALL manufacturers are using a soy based wire insulation to cut down the costs of using plastics...

read the article..

http://tasty.typepad.com/

[Tech1984]

Ok, Ok, Geeez. I said someone told me ONCE. I guess I needed a smarty pants to set me straight.