Engine idle rpm oscillations

[1994almeida]

Hi
Volvo Penta 5.0 gxi engine at idle has rpm oscillations.
Will be the IAC valve?. where I can learn to locate, clean or replace this valve.
Thanks
View attachment VID_20220921_142038.mp4

 

[Scott Danforth]

IAC is on the throttle body

Volvo uses a stock GM IAC. Mercruiser uses a Ford IAC

 

[alldodge]

I wouldn't worry to much about that area of RPM
That is the transition area between IAC and TPS take over. If it was doing it at idle (600-800) I would think more about the IAC

 

[1994almeida]

Thanks for the answers.
I upload another video.
In fact, at lower rpm the oscillation is lower.
View attachment Untitled.mp4

 

[alldodge]

If that is at idle then the gauge is off or its idling to high. Does it still do this if throttle cable is removed and its held by hand closed?

 

[1994almeida]

It's not the idle.
At idle there is almost no rpm fluctuation.
During the movie I was pulling the control lever a little bit.
View attachment VID_20210731_133145.mp4

 

[QBhoy]

Doesn’t look like the IAC to me really. More likely a fuel quality issue perhaps and or a temperature sensor telling the engine to run rich or similar.

 

[alldodge]

I'm back to I don't see an issue

 

[QBhoy]

I'm back to I don't see an issue

Tend to agree. Looks fairly normal to me and could just be temperature or variance with some throttle on.

 

[1994almeida]

Ok thank you all for your analysis.