Q: RPM's fluctuate while idling and sometimes it dies. Getting codes for multiple misfires and knock sensor.

asked by on

this is an 01 nissan altima. the problem started a week after I bought it. at first just the rpm's fluctuating and the knock sensor code. changed the knock sensor but didn't fix the problem. Mechanic said the valve cover gasket was leaking into the spark plugs, the oil pan gasket was leaking and the front main seal gasket was leaking. I changed the valve cover gasket, the plugs and wires, didn't find any oil in the plug tubes and the plugs needed changed but weren't fouled nor in bad shape, still getting the misfire code and RPM's are still fluctuating and the car dies if I don't put it in neutral and hold it at about 1000 RPM. not sure if relevant to this problem but when going down the interstate I notice the temp gauge fluctuates back and forth from cold to normal. I don't know what else to do and the mechanic acts as if they don't either.

My car has 135000 miles.
My car has an automatic transmission.

Hi there. Check the fuel injectors and see if they are working or not. While the engine is running, unplug one injector harness at a time. If the engine begins to hesitate, then the injector was working. If the engine hesitated even more, then the fuel injector was either not working or there could be an issue with the cylinder. Check the compression on the cylinders and compare them to all 4 cylinder readings. If the cylinders are all low or all high, then that is good, but if all the cylinders are all different, the there could be an issue with the valves or rings making the engine misfire. To determine this condition, a leak down tester (requires compressed air) would be used to check for a leak in the engine. If you need further assistance with your engine misfire, then seek out a professional, such as one from Your Mechanic, to help you.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. RPM's fluctuate while idling and sometimes it dies. Getting codes for multiple misfires and knock sensor.

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Car spits out white smoke when started after sitting for a short time

I have seen this many times on this engine. When this occurs during startup it is because of failed valve stem seals. In some cases the piston rings may be leaking also, but you would get smoke all the time...

Q: cylinder 3 and 4 misfire

Hi there. Check the spark plugs to see if they have burn spots on them. Switch them out with cylinders that are firing. If the other cylinders do not fire now, then the spark plugs need replaced. If the same...

Q: Fuel system, inertia relay, or pump will not start, never had problems in the past

Hello there, thank you for asking about your 2007 Ford Explorer. The first thing to do is to have the fuel pressure tested to see if the engine has pressure. Make sure the Theft Light is not on or flashing....

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.