So, what can cause, abnormally high engine idle speeds.
Dealing with idle issues, can be quite frustrating, until you identify the cause of the problem.
Once you do that, figuring out the correct solution to high engine idle, won’t take long.
A high engine idle can be caused from, a number of issues. And, can be anything ranging from, a faulty fuse to something a bit more complicated, like a leaking vacuum hose.
Diagnosing High Engine Idle, Should Start With A Visual Inspection
The first step in the diagnosis, is a visual inspection. Firstly, inspect the throttle cable and linkage for binding. Also, inspect the engine for any vacuum leaks.
So, high idle speeds waste fuel, cause extra wear and tear on your engine, and can be unsafe. Above all, what if your foot should slip off the brake as the engine revs. As a result, it could cause your vehicle, to lurch forward. It’s best to address the problem immediately, to avoid an accident.
With the engine at idle, visually inspect each vacuum hose on the vehicle. Listen for a hissing sound, which is a key indicator, of a vacuum leak.
Check For Any Diagnostic Trouble Codes (DTC)s
Next, check if there are any, diagnostic trouble codes (DTC)s, stored in the Power Control Module (PCM). Because, if there are any codes this will give us, a good starting point for troubleshooting.
Note, if you don’t have a code reader, most parts chain stores will read your diagnostic trouble codes for free.
If you find any codes, you will be able to follow them to possible causes. You may have a Error Code, P0507 meaning the high engine idle speed, is faster than normal.
Other Things That Can Cause This Problem
Idle Air Control (IAC) Valve Failure
So, if the Idle Air Control (IAC) is dirty, cleaning it may improve your high engine idle issues.
Engine Coolant Temperature (ECT) Sensor Failure
So, if the engines Engine Coolant Temperature (ECT) Sensor fails. Then, the Power control Module (PCM) may think the engine is still cold. As a result, keeping the engine (rpm) high, by commanding the Idle Air Control (IAC) valve appropriately.
There Are Many Possible Causes For, High Engine Idle:
- In vehicles that have carburetors, a bad accelerator pump or power circuit.
- The engine is overheating, and the cooling system needs repair.
- Fuel pressure regulator may be operating at, too low of a pressure and would need to be replaced.
- Ignition timing needs adjusting.
- Also, ignition problems stemming from, the distributor cap, rotor, ignition wires or spark plugs.
- The computerized engine control system is faulty.
- Vacuum leak.
- Bad idle speed control unit.
- Bad alternator.
Conclusion
Idle issues can be frustrating, but with some patient troubleshooting, you’ll have a real chance of figuring it out.
So, remember to always check the high engine idle, with the air conditioning and defroster, in the OFF setting. Because, both of these systems are designed to, change the idle speed. Then, raise the idle speed, due to demands on the engine.
BY DANNY BENDER
