Q: Rough Idle Solutions

asked by on

My truck was running beautifully and I had to switch the clutch master cylinder recently, but the idle is so rough that now my truck is dying while I'm driving as we as at a stop because it drops so low. If I keep rpms up at a stop I can keep it from dying sometimes but it's also shaking horribly when at a stop. I have been told that if I clean the mav and iacv that might help and if not to do the tb next. My question is should I just get the iacv to make it a guarantee or is it possibly something totally different all together?

My car has 166000 miles.
My car has a manual transmission.

Hi There, Although there is no way to guarantee what the cause may be, what you are describing sounds much like what happens when the idle air control valve (IAC) is not working properly. The idle air control valve monitors the air intake as it is mixed with fuel prior to being injected into the engine at low speeds and at idle. This valve is controlled by the vehicle’s computer and will adjust idle speed based upon other measurements such as engine temperature, intake air temperature and electrical system load or voltage. When you accelerate, the engine RPM increases, and as you let off the gas, the RPM slowly returns to the normal idling speed with the help of the idle air control valve making the transition from a higher RPM back down to idle speed while adjusting the air/fuel ratio constantly to allow this to happen smoothly. When the engine RPM drops below the normal range of about ~800 RPM, this often times will cause the engine to stall indicating a dirty or faulty idle air control valve.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Rough Idle Solutions

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Smog check failed due to Oxygen sensor

Hello, thank you for writing in. The first person to tell you this was correct to a certain extent. If the system is not warmed up, the readings cannot be taken accurately. However, if the engine is warmed up and...

Q: The car shut off, cannot be started

The crankshaft damper may have a loose bolt and is what's causing the lower timing chain gear to be loose. The gear pin may shear and cause the no start or loss of power. However, if this is not the...

Q: Air blows out of oil cap when car running

Hello. From my experience most motors will blow air from the oil filler cap due to the pressure generated in the crankcase from all of the moving components. If the air blowing out seems excessive, smells like fuel, or is...

Related articles

P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.