What causes car rpm to go up and down?

What causes car rpm to go up and down?

Hi There, It sounds like you may have a dirty or failing idle air control valve causing your engine idle to fluctuate. The idle air control valve is a small valve on the engine’s intake system that reads the air intake as it comes into the motor.

Why do my rpms fluctuate at idle?

Why does my engine’s RPM seem to fluctuate (runs rough)? Many engine performance problems can be linked to maintenance issues such as stale fuel, dirty air filter, fouled spark plug, and deteriorated oil. Engine hunting and surging at idle is usually caused by a fuel delivery, air leak, or governor system problem.

What was the original idle speed of a Volvo S60?

Also note that the original idle speed for these engines was 850 rpm – this was increased by 50 rpm during one of the earlier “throttle software upgrades” – which has the effect of masking this particular symptom, at least for a while.

Why does my Volvo S60 stop at 900 rpm?

1. The earliest symptom happens in this circumstance – after driving steadily for a while at highway speeds, you come off the highway and have a series of stops – at traffic lights, or whatever – each time, the engine speed will drop noticeably below the 900 rpm idle speed, then come back up to 900, with an ever-so-slight surge.

How many miles does a Volvo throttle body last?

Like me . Volvo has extended the warranty on original throttle bodies, for up to 10 years or 200,000 miles, and that discussion has, I’m sure, been had many, many times and is beyond this post. In my experience, throttle bodies last around 70,000 to 90,000 miles, though I did get 118,000 out of my original one.

How does a throttle position sensor work on a Volvo?

Within the throttle body is a “throttle position sensor” which, I understand, is nothing more than a strip of resistance film, over which the throttle place moves. Depending upon the location of the throttle plate’s edge, the electrical resistance through the sensor strip tells the computer the exact throttle plate position.

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