Engine stumbles when fan kicks on.

[GuiTaR FIXR]

So…. My 2021 ecoboost will act afool sometimes when the fan kicks on when you are sitting at a stop light on idle.

it’s like its stalling out and then catches itself and then its fine. But it’s kinda sharp / violent when it happens

i’ve noticed it’s worse if it’s in gear.

Doesn't do it all the time either, but it seems to happen more just after you start the car.

two things i think about:

Battery dying? Im going to have that checked just in case.

Idle to low? It seems to be around 700.

The strange thing is when it stumbles, it acts EXACTLY like my rx-7 did during cold startup as the Haltech ECU trued to open the IAC valve to raise the idle until it warmed up and before it caught up with the fuel setting.
It would stumble and shake once or twice until the ECU caught up with the fuel demand from the opening valve and then it would snooty out.

but these cars don't have rotors or Idle Air Control valves….. do they? ;)

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[Adam the Lighting Guy]

Hi there.

It sounds like you are describing the typical ecoboost idle shake when the a/c cycles on. Mine does it, some days worse than others.

 

[GuiTaR FIXR]

Hi there.

It sounds like you are describing the typical ecoboost idle shake when the a/c cycles on. Mine does it, some days worse than others.

Hmmm. I did notice it doing it more when the A/C was on.

So it’s a common thing huh?

 

[Adam the Lighting Guy]

Hmmm. I did notice it doing it more when the A/C was on.

So it’s a common thing huh?

Yes it is. I even had the car back at the dealer when it was still under warranty. The said no codes, can't do anything about it. A simple bump in idle speed by 100-150rpm's would solve it. When it happens, the exhaust vibrates which makes a bunch of noise. I sometimes drop it into neutral at a stoplight which minimizes it somewhat.

 

[GuiTaR FIXR]

Yes it is. I even had the car back at the dealer when it was still under warranty. The said no codes, can't do anything about it. A simple bump in idle speed by 100-150rpm's would solve it. When it happens, the exhaust vibrates which makes a bunch of noise. I sometimes drop it into neutral at a stoplight which minimizes it somewhat.

Thats exactly what i’ve been doing?

can you bump idle up with Forscan??

 

[Adam the Lighting Guy]

Thats exactly what i’ve been doing?

can you bump idle up with Forscan??

Hi again,

No, as it was explained to me here on the forum, only a "Tune" can access the idle speed. Forscan can access the BCM but not the engine Tune it self.

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