Q: Rough Idle when first started or when wet

asked by on

I am having a problem where when i first start the car and the motor bogs down and shakes the whole car and idles at 100 rpms for a minute then revs itself up to 2500 rpms, goes back to about 900 rpms for a few seconds then does the same thing again goes back down to 100 rpms etc, and it does this when wet as well, once the car is warmed up it doesnt do it and it idles at about 850 to 900 rpms which i deem normal and idles fine, unless the car does get wet then it does it unless i floor it and then stop, to which it then stops, any help, or suggenstions on what this is, im thinking its the iac, and the egr valve was already replaced along with plugs and wires

My car has 182000 miles.
My car has an automatic transmission.

Hello, I sounds like you may have a dirty or faulty idle air control valve. As you know, this monitors and reads the air intake as it enters the engine prior to being mixed with fuel while making adjustments to create the proper air/fuel ratio to be injected into the motor. Occasionally, these valves may become faulty when they are dirty, clogged or have the incorrect voltage going to them, which may cause the motor to hunt for the perfect idle as it receives these incorrect readings causing your RPM’s to fluctuate as you describe. I would suggest having an expert from YourMechanic come to your location to diagnose and inspect your vehicle.

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 when first started or when wet

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: I have a 1996 chevy k1500 and I just put a new motor in it and it will start and run and idle amazing but has no power in drive

Check to see if ignition timing is advancing per the specifications in the factory service manual as you rev the engine. Measure fuel pump pressure. Check throttle position sensor, oxygen sensors, vacuum leaks, ignition system malfunctions, bad valve timing if...

Q: Engine is overheating and heater has stopped working

If the engine was replaced and the AC refrigerant system was drained then the system should be put under a vacuum for a minimum of 30 minutes to ensure all moisture is boiled out and then leak tested to ensure...

Q: I have Pontiac G6, it shakes when idle. Usually when I drive and stops on signal. I read some code and it shows P0300 and P0301.

The codes P0300 and P0301 are coming up for a misfire on cylinder number 1. Check the cylinder for spark, fuel, and air. Check the spark plug and make sure that it is firing. The spark plug wire could have...

Related articles

Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.