Daryl's Auto Service "Independent Toyota Specialist"

Daryl's Auto Service

Technical Tips

Corolla and Matrix Models Experiencing DTCs During Freezing Weather

2003-08 Corolla and Matrix models with the 1ZZ-FE 4-cylinder engine may, during freezing weather, turn on the MIL and store one or more of the following trouble codes in computer memory: P0171 (system too lean), P0300 (random misfire), P030x (misfire in one specific cylinder) and P0133 (slow response from upstream O2 sensor).

Toyota says all these symptoms usually develop in subfreezing weather, and are most likely the result of a vacuum leak between one or more of the intake runners and the cylinder head. Installing an improved intake manifold gasket (Part No. 17171-22060) should seal off the leak and prevent further driveability issues with the little engine.

To make a definitive diagnosis, hook up your scanner and look at the short-term fuel trim PID. If you have a vacuum leak the value should be high, as the PCM adds fuel to compensate for the leak. Now spray some carb cleaner on each of the intake runners. If the fuel trim value goes much lower or negative, that's your cue that the intake gasket has sprung a leak. If the fuel trim doesn't budge, look for another vacuum leak or other causes for the lean exhaust or misfire.

Toyota Tacoma Pickup Transfer Case Shifting Difficulties

Owners of 2005-06 Tacoma pickups with the manual gearbox may complain of difficulty shifting the transfer case into or out of the 4WD Low mode. If nothing makes sense on the diagnostic front, chances are the sequence your customer is using to engage or disengage the low gear is out-of-sync with what's required to actually get things in the transfer case to mesh. Don't blame the customer, though; the transfer case instruction card on the sun visor has erroneous information. For the record, the proper sequence goes like this: First, stop the vehicle or get it below 2 mph. Next, depress the clutch pedal all the way to the floor, then turn the transfer case control switch to engage or disengage the low gear. If you don't think your customer will remember those details, an updated card with the right instructions can be ordered through a Toyota dealer. The new card goes by Part No. 36369-04040.

Toyota Supercharger: Squeak/Rattle Noises From Idler Pulley

Due to a possible out-of-tolerance condition on the idler pulley shaft, some pulleys may have bearings that spin on the inner shaft and may cause a squeaking or rattling noise. The supercharger may be perfectly fine and the source of the noise may simply be the idler pulley.