High idle 1500 rpm cold after head gasket replaced

[Scott]

New to ETCG, I recently had my head gasket replaced after antifreeze was seeping into the cylinders
Also the thermostat was replaced and MAP sensor replaced, now
the idle is running at 1500 rpm, and the idle isn’t constant. It fluctuates up and down by 100 rpm’s. Prior
to him (my mechanic) replacing the MAP sensor, the idle was surging and was stalling the vehicle. Now its constant but it doesn’t seem to go down, it also has a sound like it isn’t running right. Wondering if there is air trapped in the coolant system. Any ideas? No codes firing.

Topic

[Mathieu]

If you suspect air trap in the coolant, you can use the spill free funnel to do a bleed test as Eric shown in a video. For the 100 rpm fluctuation, It’s could be anything. Heater switch to the o2 sensor.

[WOTStang]

Do you hear any hissing sounds as the engine is running? There may have been a vacuum line missed when everything was put back together. That can cause a high idle issue as well.

[Author]

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