Guys,

I've been struggling with my idling issue on my D16z6. Can someone guide me through?

When my engine start in the morning, the RPM jumps high to 1,600+ rpm. In cold weather, it will go up to 2,000 rpm.

After the warm up, the car jumps up & down betwen 300 - 800 rpm when weather is hot. It idles 800-1,300 rpm when the weather is cold.

When the weather is hot, the car's idle drops too low and it stalls.

Lately, it idles high like 1,700 rpm after driving home from work and let idle there for 5 minutes or so. I've replaced the cold idle valve and the other valve next to the throttle body. What else?

 

throttle positioning sensor (tps) u need
while your at it clean up the throttle body

 

I haven't replaced the TPS. But, I've cleaned up the throttle body a few times already.

 

Have you checked the FITV?

 

Also check for vacuum leaks.

 

I've taken the car to machanic for vacum leak testing. He reported no leak.

How do I test if TPS and FITV are functioning or not?

 

Anyone can help?

 

Your temperature swings point toward the FITV and the IACV, both of which commonly have thermowax inserts which expands with heat thereby closing some of the excess air (they do this to allow for extra air during cold starts thereby not starving the engine).

A lot of times the FIT can be closed off (many people just close it all the way) lowering the amount of excess air that is injected into your intake. This excess air often confuses the ecu and in turn causes idle hunting fluctuations.

Take your FIT off and remove the 2 screws holding the plate on the end. Tighten the white insert (I tightened it all the way and backed it off a hair). Reinstall.

The TPS (depending on your model) may have 3 wires. With your key in the ON position (engine off), measure the center wires voltage level under closed throttle condition. This value should be close to 0.5 volts. Turn the throttle plate so that it is wide open throttle and take another reading. This value should be 4.5 volts. To adjust, loosed the 2 mounting screws and pivot the TPS until the values are acceptable and retighten.