What would make my car run rough?

What would make my car run rough?

4 Common Reasons Why Your Engine May Be Idling Rough

• Vacuum Leak. Most vehicles have a maze of hoses throughout which create a vacuum for both fuel and air.
• Spark Plugs. A rough idling engine can be caused by spark plugs or spark plug wires.
• Dirty Fuel Injector.
• Carburetor Problems.

Can ECM cause rough idle?

Erratic engine behavior may also indicate a bad or failing ECM. A faulty computer may cause the vehicle to intermittently stall or misfire. The symptoms might come and go and not appear to have any sort of pattern to their frequency or severity.

Where is the ECM relay located?

engine main fuse relay control box

How does the computer control the alternator?

An external voltage regulator controls the alternator by toggling the other field terminal; that is, it switches the other field terminal on and off to ground. Second, if battery power is present at the one field terminal, check for battery voltage at the other field terminal with the ignition on, engine off.

What tells the alternator to turn on?

Most alternators use diodes inside a rectifier to turn Alternating Current (AC) into Direct Current (DC) for use by the system. When one or more diodes go bad, AC can leak into the electrical system.

What is R and F on alternator?

The R and F terminals are the ‘Reference’ or voltage sense terminal and the ‘Field’ terminal. The color on the spade connectors doesn’t matter, you will have to use a multimeter to determine which connector goes to which pin. The R will be hot at all times while the F will only be hot when the ignition is keyed on.

What does F mean on alternator?

“F” stands for field. Voltage on the field determines how much output from the alternator. The regulator varies the voltage on this wire to keep the system at more or less 14 volts output.

What does B mean on alternator?

Locate the terminal on the alternator labeled “B”, “Bat” or “Pos.” All alternators have this terminal. The wire that connects to it is red and goes to the battery. It is a heavy duty wire as it has to carry high current.