Hello, My 94 Accord is surging while idiling. RPMs up and down.
runs good while going down the road, problem only while at idle.
Thank you

 

Possibly need to bleed the coolant or clean out the IACV.

 

make sure the coolant is full and the block burped thru the 12mm bleed screw at the T-stat housing.
The FITV might need adjusted; on your car it lays sideways under the throttle body opening.[best to remove the air snorkle tube] Remove the 2 phillips screws and under the lid is a 'split' nylon screw with a brass cone sticking thru it. Turn the screw in a couple turns and try it again. If you crank that 'split' screw all the way down when cold you can lose the cold start fast idle.
When the engine is warm you should not be able to hear air bypassing in the valve.

 

Before touching any of the factory adjustments, also check to see if you have a vaccuum leak somewhere. I just fixed this problem in my car, i wokred on it for over 3 days before i found out it was a leaking throttle body gasket. did you do any work on your car lately?

The quickest way to check is to take the intake tube off the throttle body, and with the car running, put your hand over the opening. If the car still runs you have a leak. The car should die almost instantly if you have no leaks... when my TB gasket was leaking, the car would still run at about 100RPMs with my hand over the TB.

Next check for air in the coolant like hondadude said, and also check if your car is throwing any engine codes (i.e. is your check engine light on?)

One of the reasons your car is idling up and down is that the car is trying to correct a condition where its seeing more air than its expecting, so its trying to correct itself, or air in the coolant is confusing one of the temp sensors.

Are you idling within factory spec? (650-750 rpms when the car is warm) about 1700 when its cold (fast idle valve is open)?

Good luck!!

 

Broken TPS (throttle position sensor).

 

You have gotten some good advice. The problem areas are:

Bad or dirty idle air control valve

air leak (leaky gasket) in the intake manifold area or vacuum leak (hose off)

bad throttle position sensor

faulty MAP sensor (in the control box on the firewall)

An easy way to start is to locate the components in question and start unplugging them (the wire or the vacuum hose) one by one while the engine is running and see what happens. If the up and down stops, you have found the problem.

Once you are finished, make sure to reset the idle speed and the computer (pull outs its 7.5 amp fuse for one minute) -- this is important.

Good luck.


Modified by gulfview at 8:11 PM 1/18/2007