What causes high idle and high engine speed?
This valve is prone to sticking. If the plunger is backed out too far, this can affect a vacuum leak, causing a high idle after the engine has warmed to operating temperature. This can also result in a pulsating/fluctuating engine speed. While most repair manuals recommend replacing this valve assembly, it can be removed and cleaned.
How often does the engine idle during a drive?
• The learned idling air flow volume remains at the maximum or minimum volume five times or more during a drive cycle. • After driving at 6.25 mph or more, the actual engine idling speed varies from the target idling speed by between 100 and 200 rpm, five times or more during a drive cycle.
What is the problem with the idle air control valve?
The problem may involve an annoying change (up/down) of engine speed while cruising at a steady pace, a low drop (or even cut-out) at idle or when approaching a stop, a wild high engine speed of several thousand rpm followed by a drop to near zero, etc. • Dirty/sticking IAC (idle air control valve) (P0505)
Can a failed IAC cause engine stalling at idle?
A problem with the IAC should throw a P0505 code. A failed/problematic IAC can cause engine stalling when off-throttle, and/or excessively high engine rpm, particularly at idle. The IAC, signaled by the ECU, controls the throttle opening at idle.
This valve is prone to sticking. If the plunger is backed out too far, this can affect a vacuum leak, causing a high idle after the engine has warmed to operating temperature. This can also result in a pulsating/fluctuating engine speed. While most repair manuals recommend replacing this valve assembly, it can be removed and cleaned.
A problem with the IAC should throw a P0505 code. A failed/problematic IAC can cause engine stalling when off-throttle, and/or excessively high engine rpm, particularly at idle. The IAC, signaled by the ECU, controls the throttle opening at idle.
• The learned idling air flow volume remains at the maximum or minimum volume five times or more during a drive cycle. • After driving at 6.25 mph or more, the actual engine idling speed varies from the target idling speed by between 100 and 200 rpm, five times or more during a drive cycle.
Why is the idle speed too high on my Wrangler?
The usual cause of abnormally high idle speeds are vacuum leaks or an inoperative idle speed control motor. A vacuum leak on a fuel injected engine will cause high idle. The oxygen sensor will detect the extra oxygen that is entering the engine through the vacuum leak and will signal the computer the exhaust is lean.
Why is the idle speed on my 560sl so slow?
To fix this problem could be a myriad of complications (welcome to the M117 engine), but I suggest starting at the idle air valve (top front of the engine under the air cleaner housing) and clean it out with some carburetor cleaner. After that, it could be any of the rubber hoses and grommets in that engine.
Why does my car idle at a higher RPM than normal?
Updated January 19, 2019. If your car seems to be revved up to a higher-than-normal RPM while idling, it’s not necessarily a problem. If this problem happens while the engine is cold, it may be part of the engine’s design.
What causes high idle speed on Mercedes Benz?
High idle on the M116/M117 engines is usually caused by vacuum leaks. On my M116 (essentially the same) I had to take apart the whole top of the motor and replace EVERY piece of rubber, especially the rubber rings that seal the two halves of the intake.
Why does my car run at 1200 rpm?
Some cars, especially older cars with carburetors are designed to run at 1200 rpm or so until they are warmed up. And in modern cars, if you are running several accessories, such as the air conditioner or heater, the engine’s onboard computer may be telling it to run at a higher RPM to provide the necessary power.