Why does my Sentra engine rev up and down?
Choose your car for a more accurate estimate. The idle is controlled by the idle air control valve and if it cannot keep the engine idling it will keep trying to rev the engine up to compensate. A vacuum leak, sensor that has failed, or an EGR system malfunction could potentially be the cause of the erratic engine you’re experiencing.
Why does the RPM drop when I put the car in neutral?
Check the timing both in and out of gear. If the timing is falling way back in gear, that’s most of your problem. Usual culprit is a centrifugal and/or vacuum advance kicking in at idle. As soon as you throw it in gear it drops back, making the RPM drop worse than it would ordinarily be.
Why does my car rev up when in Park?
I’ve seen questions about engines revving when braking and when idling, but my engine revs way up (and stays up) whenever it’s in park–whether on startup or shifting to park. It doesn’t rev unusually like this in any other gear. What would be the most probable reasons?
Why does my car rev up and down when idle?
My car has an automatic transmission. The idle is controlled by the idle air control valve and if it cannot keep the engine idling it will keep trying to rev the engine up to compensate. A vacuum leak, sensor that has failed, or an EGR system malfunction could potentially be the cause of the erratic engine you’re experiencing.
Check the timing both in and out of gear. If the timing is falling way back in gear, that’s most of your problem. Usual culprit is a centrifugal and/or vacuum advance kicking in at idle. As soon as you throw it in gear it drops back, making the RPM drop worse than it would ordinarily be.
What should the idle speed be in neutral?
In Park or Neutral it idles up at 1500. But when I drop it into drive it goes all the way down to around 600. This seems like an excessive drop to me. I had to set the curb idle high so that when it went into gear it wouldn’t stall out.
Why is my car revving up at the idle speed?
If your engine RPMs are bouncing up and down and your engine can’t maintain a steady idle speed then there is likely a problem with one of the components attached to your engine or a problem with one of the sensors used to keep your engine running.
Why does my car keep revving in Park?
The car’s computer can then make adjustments to the air/fuel ratio to keep the engine running efficiently. Over time your oxygen (commonly referred to as O2 sensors) can be gummed up with carbon deposits as the burnt air/fuel mixture passes over the O2 sensor.