The Causes of an Idle Surge

The Causes of an Idle Surge

Fluctuations in engine idle speed can be annoying and may even cause stalling at idle. Engine stalling can be dangerous, because power assistance is lost to the steering and brakes. Idle speeds below those specified by the manufacturer will affect the performance of the power steering pump, alternator and AC compressor. Emission control devices also require a minimum engine speed for effective operation. Surges that accelerate engine speed could cause unexpected vehicle movement.

Air Supply

A clogged or obstructed air filter can cause surging at idle, and foreign objects can enter the filter housing at any time. Any debris in the filter or housing might restrict air flow to the engine enough to affect idle speeds. Clean the throttle body or carburetor venturi(s) after replacing a severely dirty air filter. Aerosol products designed for this purpose are available at any auto parts store. Instructions for use are on printed on the can.

Fuel Supply

Fuel filters can become restricted and deny proper delivery at idle speeds. Mechanical fuel pumps may overcome restrictions and performance deficiencies at higher speeds. Incorrect idle speed settings or fuel mixture adjustments, and malfunctions in the fuel vapor recovery system can upset engine idle capabilities of carbureted engines. The appropriate fuel system cleaner added to the fuel tank can open clogged passages in injectors and carburetors that may be causing the surge.

Vacuum

Any extra air entering the intake manifold will lean the mixture at idle and surging will result. A visual inspection of vacuum hoses may reveal cracked or leaking hoses. A short length of tubing can serve as a make-shift stethoscope to pinpoint any hissing noises heard on a running engine. Cracked or clogged positive crankcase ventilation valves can adversely affect engine idle quality. Idle solenoids or controls should be adjusted to specifications after vacuum leaks are repaired.

Engine Issues

Ignition system problems can contribute to idle surge. Ignition timing and the condition of spark plugs and related components should be be checked before seeking professional assistance. Lack of compression, and valve timing and condition issues are complex to diagnose and usually affect overall performance, but can be more pronounced at idle speeds. Contributing emission system flaws may require advanced testing techniques or equipment. A visit to a qualified repair facility might be necessary.

How to Fix the Accessory Power Outlet in a Car

How to Fix the Accessory Power Outlet in a Car

Current technology has transformed a car’s accessory outlet from a mere cigarette lighter to a vital piece of the commuting puzzle. Paper maps have gone the way of cassette players with the advance of global positioning satellite navigation units and mapping applications on cellular phones. These 12-volt sources now power devices that provide navigation, traffic updates, weather conditions and emergency communication capabilities making car travel safer and more comfortable.

Determine If the Outlet Is Bad
Try a different accessory with the outlet. If the second accessory does power on, the problem is the original accessory and not the outlet. If both accessories fail to turn on in the outlet, the outlet is probably the culprit. If this is the case, proceed with further troubleshooting steps to determine the root cause of the outlet failure.

Check the Fuse
Accessory power outlets are protected by a fuse in a fuse block. It is there to prevent the outlet from overdrawing power and possibly creating a fire due to a short or misuse. Your owner's manual has a listing of all of the fuses in the car and a diagram highlighting the exact location of the fuse block. Remove the fuse using a fuse puller and inspect the metal line the plastic housing. If it is broken, replace it with a new fuse of the same amperage. The fuse block cover may have spare fuses you can use. Never use a replacement fuse with a higher amperage rating than the one you are replacing.

Check the Wiring
Use a multimeter’s DC volts setting to get an idea of what’s going on with the outlet. With the car ignition in the accessory position, insert the red lead into the outlet and make firm, direct contact with the conductor in the center of the outlet. Use the black lead to contact the side of the outlet without touching the red lead or the center conductor. If the meter reads anything below 12.0 volts or no current at all, find the problem in the wiring. Remove the negative battery cable and check for continuity between the side of the outlet and the outlet’s ground point, the outlet center conductor and any junction point between it and the fuse block, and hot shorts or short to ground. Repair any break in the wiring or shorts.

Replace the Outlet
If the fuse is OK and you didn’t find any breaks or shorts in the wiring, it is safe to suspect the outlet itself. A multimeter can help determine this as well. Unplug the power outlet from the wiring harness so that the outlet is electrically separated from the rest of the car. Jumper the red and black wire in the outlet's electrical connector, then insert the multimeter leads into the outlet as you did to check for voltage, but this time set the multimeter for continuity. Because the wires themselves have already been tested, an open circuit here will verify that the break is inside the outlet itself. If the meter reads no continuity, replace the outlet.