Engine Trouble Codes

Under The Hood: When key remote fails, check batteries, then car

QUESTION: I have a 2006 Camry LE 4-cylinder with 23,000 miles. Both hand-held remotes have stopped working. No doors, no trunk and no panic button. I replaced the batteries, but it didn't help so I presume the problem is in the auto. The door locks work fine using the inside lock buttons. Any ideas?

—Fred Gerbino

ANSWER: Fred, let's start by taking another look at those remotes. Try scrubbing the battery terminals with a pencil eraser, then reinsert and rotate the batteries a few turns to insure the best possible connection. If both remotes still fail to function, the problem appears to be in the vehicle.

Your Camry's door control receiver is located within the rear roof pillar on the right side. Upon receipt of a transmitter signal, this box communicates with the body's electronic control unit, which sends commands to the appropriate door or trunk lock actuators. Diagnosis of these components and connecting wiring gets pretty techie after a check is made for diagnostic trouble codes stored in the electronic control unit. The only thing I can think of to have you check, prior to seeking professional diagnosis, is to be sure the dome light fuse is OK.

Q: Why do I want "variable valve timing"? I've seen this promoted and wonder if it's worth the added complication.

—Jason Shuller

A: Variable valve timing, or VVT, is a neat system, as it optimizes engine performance over a wide range of engine speed. In addition to adjusting camshaft timing, many systems also have the ability to vary valve lift and/or duration. Without VVT, an engine's camshaft must strike a compromise between low speed torque, minimal emissions, best fuel economy and high output at faster engine speeds.

VVT typically utilizes a hydraulically operated camshaft sprocket that allows the camshaft to be driven up to about 40 degrees ahead of or behind the sprocket, similar to how you might rotate your wrist relative to your elbow. Cam and crank shaft position sensors keep the PCM (Powertrain Control Module) informed of actual cam position, and a control solenoid is pulsed to vary the delivery of engine oil to the sprocket actuator, which moves the cam to the desired position.

VVT allows the engine to be docile and efficient, then a tiger when called for. BMW's system is so versatile it eliminates the need for a throttle. A free-breathing intake reduces pumping losses, boosting engine efficiency by 10 to 15 percent.

From a durability standpoint, VVT looks good to me. With the exception of the fairly expensive cam sprocket, much of the rest of the system, such as the computer and sensors, was already in place.

Synthetic Motor Oil 10w30 | Motor Oil

Once my 2000 Trans Am warms up, it is knocking or pinging under moderate to high load. It runs fine when the motor’s cold. I almost always use Shell 93 octane gas, and I have always used 5W30 or 10W30 synthetic blend oil. The car has 115k miles on it.

The sound is detonation (also known as spark knock).

It’s cause by a long list of things. Carbon, too high of compression for the octane fuel being used, too low of octane fuel for the compression, bad fuel/water in fuel, engine running too hot, inlet air into engine too hot, timing too advanced, air/fuel ratio too lean, lugging the engine around (driving up hills in 5th gear), spark plug heat range too hot for the compression

The odd thing is, it shouldn’t be happening on your car with out setting off a trouble code.

You have a knock sensor in the block that picks up knocks of any type and retards the timing untill knock is gone.

Sounds like the knock sensor aint doing it’s job.

Now next thing is why do you have detonation in the 1st place on a stock engine…

Only things that come to mind is.

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