Skip the auto shop - Our mechanics make house calls

Q: Changed/removed the thermostat, now idles up and down over and over... 1994 Honda Accord

asked by on

I have a 1994 Honda Accord I took out the thermostat and I checked all the hoses when I put everything back together and Crank up the car and let it run for a while then I noticed the RPMs is going back and forth Rebbing up and down so I took off the radiator cap and I looked in the coolant was running out I check the hoses there was no pressure on the Hose but the car just kept Rebbing up and down so I cut the car off

My car has 125497 miles.
My car has an automatic transmission.

Hello - if I understand correctly, you may have completely removed the thermostat, rather than replaced it? If so, the engine will warm up more slowly, and that will confuse the engine management computer, and cause the engine to run with a richer fuel mixture. The oxygen sensor will try to compensate for this by commanding the fuel injection to use a leaner mixture, and a continuing cycle will follow. It is also possible that you bumped a vacuum line or electrical connection for the idle air controller and that component is not operating properly - causing an eratic idle. I recommend a rough engine idle inspection performed by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, give you an accurate assessment of damage and cost estimate for repairs.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  • Home
  • Questions
  • Changed/removed the thermostat, now idles up and down over and over... 1994 Honda Accord

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: How do I use the power sockets?

The power sockets allow you to power certain electronic devices. Your vehicle can have two power sockets: one in the center console panel, and one in the center console compartment. To use the power sockets, pull off the covers and...

Q: Bad mileage & strong gas smell in dipstick/oil pan - 1996 Nissan 300ZX

Okay, so usually the answer to problems are usually hidden in the fine details. The whole reason you started noticing a problem was the gas mileage. If this was my car, I would be thinking that I have a fuel...

Q: Suddenly will not start - will crank but will not start.

There is no need to tow it at all. YourMechanic can perform a mobile no-start diagnostic, and if parts are required install them right there at your present location. Since your "no-start" is not an intermittent problem, the cause can...

Related articles

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...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.