dusty98

I checked my timing on 90 4Runner in an attempt to solve an ongoing ping problem. Per my decal on the hood, I jumped the diagnostic box settings & then set the timing to 10 degrees.

To achieve 10 degrees, I had to retard the timing all the way, does this sound normal? I would think 10 degrees would be a mid point and you could advance/retard the timing from there.

The setting helped a little, still pings on the highway though. Is there a way to test the knock sensor? Or is this something better left to the dealer and diagnostic tools?
Thanks again,

Jay

Jumpering the diagnostic connector does 2 things. It puts the engine in a mode that enables you to adjust the engine idle and timing. And also reports any DTCs (Diagnostic Trouble Code) stored in memory.

Before setting the timing verify first that the check engine light is flashing. If it is not, verify your jumper wire connection.

If there is a problem with your knock sensor, the check engine light will flash a DTC (Code 43, if I remeber correctly). Refer to THIS PICTURE, for how to read stored codes. Without the ECU detecting a problem, I would doubt anything is wrong with your knock sensor.

There is a ohm specification for the resistence value of the knock sensor.

3VZ-E V6
Since the knock sensor is located under the intake manifold, in the valley between the cylinder banks, it is impossible to gain access without taking alot of the engine apart. The only measurement you can make is the resistance of the wire at the engine ECU. This reading should only be about 10 ohms higher than the specification for the knock sensor itself, adding in normally expected wire resistance.

22RE 4cyl
The knock sensor is located above and to the right of the starter on the passengers side of the engine.

If combustion temperature is to high, the air-fuel mixture can pre-detonate (ping). So you might also want to check your EGR system. By design, the EGR system routes exhaust gases back through the intake to lower the output of NOx gases, by lowering combustion temperature. Applying vacuum to the EGR valve at idle, should stall the engine, If it doesnt its possible the EGR valve or passeges are clogged with carbon, or the EGR vavle itself is defective. Also check to ensure you have vacuum (about 10in-hg) at the EGR vacuum hose at 2500 rpm.

The fact that you have to turn the Distibuter all the way one direction concerns me. If proper connection is made with the jumper wire and you still need to do this, I would suspect Cam timing to be wrong. You would need to check your timing belt for proper installation. Adjust or Replace as necessary.


Good Luck

Jay

dusty98

Thank for the detailed info Jay!
The check engine light was flashing while I had it jumpered. I didn't check for codes though. Duh....
I had the EGR valve replaced a year or so ago, but its good to know a way to check it out and make sure its working.
I'm not far from another timing belt so if these check out, it'll be a good time to check the cam timing and everything else while in there.