Went to work last night and the CEL came on. Stopped by Advance Auto Parts this morning to see what code was sent. The guy told me it's a vacuum leak. Came home, took the gas cap off, and reinstalled it. Disconnected the battery and hooked it back up after a minute. CEL is still on. Looked at the PCV hose on top of the valve cover, and the hoses to the brake booster. All look good, no cracks or splits. Any ideas on where to look for a leak? Truck is a '00 Ranger, 2.5L and 5 speed manual transmission.
Thanks,

 

What code was it? A vacuum leak could be in one of many places... hose, throttle body, air intake, intake manifold, etc...

Unhooking the battery won't turn off the CEL. Sometimes you can drive it for a while and the light will go off if the problem has gone away, otherwise a scanner/reader can turn it off.

.

 

He didn't give me a code, just said vacuum leak. I was to tired to ask, I plan on stopping at a different store Tuesday.

 

Update: Stopped by O'Reilly Auto Parts this morning for another read. They pulled code P0455, Emission Control System Gross Leak. I've got a locking gas cap on it, been on for a year. I have 130 miles since the last fill up, used 1/4 tank of gas. took the gas cap off, and didn't see any cracks in the seal.

On the way to work, after about 10 miles, the engine started racing when I pushed in the clutch and let off the gas. Sounded almost like the gas pedal staed depressed. Same thing this morning, turned the truck off, everything went to normal, then after about a mile it started racing again.

Truck is going to sit until I can figure this out.

 

Most problems with the engine racing are do to either vacuum leaks or a gunked up idle control. Since you have an evap code, lets assume vacuum leak or a defective solenoid. I will assume you are not familiar with evap functions.

The vehicle will create a mild vacuum in the gas tank to purge the gas fumes from the tank. These fumes are held in the purge canister. When a solenoid opens, these flow into the engine and are burned. This prevents evaporated gas from just escaping into the air. This system can develop leaks. You code does not necessarily indicate a bad gas cap, but does indicate that vacuum is in fact leaking, which seems to be confirmed by the racing at idle.

However, to confirm that you need to eliminate other factors that can cause that fast idle. Clean the control valve by spraying some throttle body cleaner through there. Do not use carb cleaner. Carb cleaner uses different concentrations of different solvents and can damage the plastic and rubber parts in the TB, as well as the transparent film on the metal. If that doesn't work, then the IAC will need to be replaced. That part is not too expensive and is fairly easy to replace yourself.

Your vacuum leak may also be that the purge solenoid is not fully closing, which the computer will pick up on, and might be what your code is really telling you. The symptoms will be similar to a vacuum leak.

 

Bear River,

You assumed correct about my knowladge about the evap system. I will try what you suggested.

 

Thanks to Bear River. Replaced the IAC and so far no more problems for a couple days now. This past winter the truck developed a "super charger" type whine under acceleration. this has gone away with the IAC replacement.