Engine Performance problem
2000 Ford Focus 4 cyl Front Wheel Drive Manual 165000 miles
Started when it was cold outside and happens more often then. When I start the car it doesn't hold a consistent idle. It will surge up a couple of times and eventually, within a couple of minutes, the idle will drop so low it usually stalls. When I drive the car it is perfect, no problems. After it is warmed up the idle will usually rev up when I come to a stop. I pull up to a light, stop, put it in nuetral and the engine will rev up. The only way to get it to stop is to put it in gear and let the clutch out a little. This will usually drop the idle back down and then it will idle fine. I put new plugs and wires on it, one of the wires was arking to the positive battery lead. I have had the ignition system flushed, although I am not sold that it really does anything. I have checked the plugs several times and they look good. There are no warning lights and the check engine light never comes on. Can I still pull codes off it if the light never comes on?
You can always scanned the computer anytime don't be surprise if it pops a code without the light coming on.
Clean out the Idle air control valve and test the throttle position sensor.
Here's how to clean the IAC valve: Disconnect the air intake ductwork from the throttle body.
Start the engine, then increase and hold the idle speed to 1,000 to 1,500 rpm.
Spray the throttle cleaner or engine cleaner into the throat of the throttle body, aiming for the idle air bypass port (usually located on the side or top of the throttle body opening). Give this area a good dose of cleaner (about 10 second's worth).
Turn the engine off to allow the cleaner to soak into the IAC passageway.
Wait about three minutes.
Restart the engine, rev and hold at 1,000 to 1,500 rpm, and repeat the cleaning process again.
Turn the engine off again, and reattach the air intake ductwork to the throttle body.
Start the engine and rev and hold to 1,500 to 2,000 rpm until no white smoke is coming out of the exhaust pipe.
If this fails to make any difference, you can remove the IAC valve from the throttle body and spray cleaner directly on the tip of the valve and/or into the ports in the throttle body. Let the cleaner soak awhile, repeat as needed, then reinstall the IAC valve, start the engine and run it at 1,500 to 2,000 rpm as before until no white smoke is seen in the exahust.
If the idle speed still surges after this, the IAC valve is defective and needs to be replaced.
March, 17, 2009 AT 5:53 AM
Ok, thanks for the info. I will check on that first thing tonight. I will let you know what I find.
March, 19, 2009 AT 8:01 PM
I pulled the IAC off and cleaned it, however, it showed no signs of being dirty. The gasket was cracked a little but it didn't look bad enough to cause any problems. Is there any way to check the IAC to see if it is working? It is an $80 part and they won't accept it as a return if it doesn't fix the problem. Oh we ran the code reader and couldn't get it to pop a code either.
March, 22, 2009 AT 8:39 AM
I replaced the IAC and the idle still surges. It is a little better, but it still surges. We hooked up a reader and tried to pull a code, no joy. No matter what we do, we can't get it to pop a code.
Any other suggestions?
I thought maybe the Throttle Position Sensor, but I figured you'd see the problem through the entire RPM range.
ANyway, I am at a loss, my mechanice is at a loss. I just want to get the car to idle better.
Thanks in advance for any assistance you can offer.