Why is car revving by itself?
It sounds like you may have a dirty or failing idle air control valve. This valve is controlled by the vehicle’s computer and will adjust idle speed based upon other measurements such as engine temperature, intake air temperature and electrical system load or voltage.
Can alternator affect idle?
Modern vehicles require a steady electrical current of specific voltage in order to run properly. Drops in electrical output from a failing alternator can cause these systems to malfunction, leading to a poorly running engine. Symptoms will be rough idle, misfires, poor acceleration, hesitation and stalling.
What are the problems with the C70 engine?
Once the system plugs up, crankcase pressure builds high enough to cause oil to be forced past engine seals resulting in oil leaks around the engine. Another problem with this system is the many small vacuum lines used become brittle and crack, rendering the system inoperable as well as causing idle and drivability issues.
What’s the problem with my 1993-2000 850 S70?
All 1993-2000 850, S70, C70 and V70 models (as well as most 2001 2008 S60, S80, V70 and XC 90 models) use a plastic gas cap door hinge that commonly fails at around 60,000 miles or so. Not the end of the world, but it does leave your gas door hanging from the side of your Volvo, which doesn’t look too cool and is not good for the paint job!
What are the most common problems with 1993-2000 Volvos?
All 1993-2000 850, S70, C70 and V70 models (as well as most 2001 2007 S60, S80, V70 and XC 90 models) use a complicated crankcase vent system to prevent the build u of pressure inside the engine. Since the mid 70’s Volvo owners have had problems with this system clogging up with oil deposits.
What causes an engine surge when the ECU is off?
If closed TPS voltage changes, the ECU may assume that your foot is on the throttle, causing a richer fuel mixture to be delivered. This can also be caused by a faulty TPS, or even a poor ground. With the engine off, check TPS voltage with the accelerator pedal relaxed. Then work the pedal a few times and see if the voltage changes.