2003 Vibe GT with mega high RPM

canvibecanvibe Member Posts: 1
edited November 2020 in Pontiac
2003 Pontiac Vibe GT. 6-speed manual transmission. 2zz engine.

When we take the car out for a drive, as soon as you drive away and any throttle is applied and then the clutch is applied, the engine RPM quickly climbs to the 4000 RPM range. It never comes down and the only way to bring it down is to kick the engine to 4500-5000 RPM. Once kicked/punched, the idle drops to approx 1200 RPM...

... until you apply even just a little accelerator again, then the engine RPM climbs quickly again to 4000 RPM.

Here's a video demonstrating the issue:





Every single time the accelerator is applied, the engine RPM jumps to about 4000 RPM.

Standing still idle seems perfect. No rough idle. Car exhaust seems to be burning clean.

No error codes.

After bringing the engine up to normal temp, we did an idle relearn process. The engine idles at around 850. This seems excellent. No RPM issues until you just actually start driving.

Work already done:
  1. Throttle body was removed and cleaned well with proper throttle body cleaner. It was pretty dirty. Cleaning made the problem much worse. Throttle body gasket is in good shape.
  2. New Idle Air Control Valve. I'm confirmed the new valve is receiving proper power and opening when power is applied. Gasket is in good shape.
  3. New Mass Air Flow sensor. I'm pretty sure the old sensor was working fine, but I replaced anyways.
  4. No obvious vacuum leaks can be found.
  5. No engine error codes. I'm using OBD Fusion app.
  6. New Throttle Position Sensor.
  7. Idle relearn steps complete.
  8. I'm scratching my head as I'm out of ideas.
Any advice on where to investigate would be very much appreciated.

Comments

  • thecardoc3thecardoc3 Member Posts: 5,479
    First thought, 4000 rpm is too high to be caused by the Idle Air Control valve, the throttle plate has to be sticking open slightly. To prove that I would be monitoring scan data and watching the IAC counts, desired idle speed versus actual, minimum TPS voltage both when working normally versus when it's idling too fast. Another possible cause of a high idle speed situation is the power steering idle boost, Testing from there would be dependent on what I found with these first checks.
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