Two car problems

#1

1997 Honda Accord is suddenly having 2 problems. 1 - When car is idling, engine revs from 1000 rpm to 1500 rpm in a cycle. Foot on the gas doesn’t help.

2 - Fan which normally stays on in hot weather after car is turned off is now staying on in 30-40 degree weather.

Both problems started yesterday but I can’t imagine a connection.

#2
  1. possible vacuum leak
    leaking EGR valve
    Plugged PCV valve
    Clogged air filter
    Leaking head gasket (do a compression check)
    Faulty ignition system or faulty emissions system

  2. Not sure…maybe a relay fault?

Any CEL for either of these problems?

#3

check for an engine coolant temp sensor, whne these go wacky they cause PCM to to wacky things.

#4

well, Roadrunner, you never mentioned the brakes, or tires or muffler!

#5

Check the level of anti-freeze in the radiator. If it’s low, the engine won’t cool as it should, and the radiator fan will continue to run. Or, a defective engine coolant temperature sensor could be keeping the fan running overly long.

#6

I agree with Roadrunner about question 1. I will also suggest a dirty Idle Air Control valve.

  1. There are two temp sensors, one in then engine and one in the radiator. The one in the radiator signals the cooling fans. Check the coolant level and the temp sensor in the radiator.
#7

About the idling problem, how old is your battery? Sometimes the engine will cycle like that to charge a dying battery. You can get the battery checked for free at many auto parts stores.

About the second problem, when is the last time you changed the coolant/antifreeze or had the cooling system checked? It sounds to me like your car might be overheating slightly, in which case you want that fan to stay on in 30-40 degree weather.