Q: Erratic idle on cold start 2007 Audi a3

asked by on December 31, 2017

I have a 2007 Audi a3 the first time I start my car in the morning is usually rough, it seems to crank slow but always starts up. After it starts the rpm is pretty erratic it goes up and down from 1000rpm down to 600rpm and back up and down. After the car warms up it idles fine. The car drives fine after the fact, it's an automatic also the check engine light seems to come and go but the idle problem doesn't stop.

My car has 113000 miles.
My car has an automatic transmission.

Car is hard to start Inspection $94.99 - $114.99 Get a Quote

Hi Steven. Thanks for the question today. In most cases, what you’re describing is caused by either a failed cold start injector, mass air flow sensor, or an idle control valve that is clogged with excessive carbon deposits. This is rather common in vehicles about 10 years old. Before you decide to make any repairs, it’s best to have a professional mechanic come to your location and complete an on-site inspection first.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

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


Experienced Mechanic?

Earn up to $70/hr

What others are asking

Rough/ low idle, smells rich, and has a knocking sound near rear (like exhaust is rattling).
Hello. This may be potentially related to the mass air flow sensor (https://www.yourmechanic.com/services/mass-airflow-sensor-replacement) or throttle position sensor (https://www.yourmechanic.com/services/throttle-position-sensor-replacement). Initially, it may have been a faulty O2 sensor (https://www.yourmechanic.com/services/oxygen-sensor-replacement), but now since that has been replaced, that part of the system...
Steering is extremely tight. Moreso when not moving or moving slow. Rack and pinion was suposedly done
Hello. It sounds like something is mechanically binding and/or you are not getting full power assist. If it is mechanically binding, one cause would be defective strut bearing plates (top of strut in wheel well). You can evaluate that by...
Question about acceleration improvement.
There are zero options to "improve" the acceleration of the vehicle very simply because if such "options" actually existed Toyota would have already implemented them on the assembly line. That is who wouldn't want better acceleration? Toyota selected and tuned...
Cannot get engine light or DSC reading to go off 2002 Jaguar X-type
Hi - there must still be a problem code which is eluding them, perhaps something Jaguar-specific. The Dynamic Stability Control (DSC) warning light may be simply a dirty or failed wheel speed sensor (https://www.yourmechanic.com/article/symptoms-of-a-bad-or-failing-wheel-speed-sensor). I would recommend a Check Engine...
Clunking while decelerating
This is a common sign of a failing CV joint. A CV (Constant Velocity) joint is a shaft that connects the transmission to the wheels, essentially transferring the power from the drive train directly to the wheels. The CV joint...
When I get to about 60 mph and higher I hear a loud rattle like noise, what could it be?
Hi there. Check under the vehicle for any heat shields that could be moving during high wind turbulence. Also, look for any loose wiring or parts that can move when turbulence is making it move around at great speeds. If...
ASD relay not activating
Hello. If you require an accurate wiring diagram you will be able to find one in the vehicle's service manual, or a quality repair manual. You may also be able to acquire the diagrams through a dealership or shop, or...
Expedition misfires going down road at about 40mph. It will eventually "punch" through and take off smoothly at faster speed. Che
Hello, thank you for writing in. The first step is to have the vehicle scanned for diagnostic codes. Then you can take that information and find out what is causing the misfire. Without that information it is a guessing game....
Clunk sound when I set on reverse and when I let go of gas pedal. Rattle noise has been increasing over bumps.
Hi there. Sounds like one or both CV Shafts are loose and are moving when you put the transmission in gear. Plus the squeaking noise is from the disk brakes system on the front as they are being forced to...

Related articles

A Buyer’s Guide to the 2012 Audi R8
The The 2012 Audi R8 is a two-door sports car with plenty of power and performance to offer. It manages to combine an aggressive stance and plenty of get-up-and-go with the comfort and interior refinement you’d expect from a German...
A Buyer’s Guide to the 2007 Ford Crown Victoria
This This enduring Ford classic enjoyed a nearly two-decade run before being discontinued from the retail market with the 2007 model-year being the last. Ever-popular with law enforcement (for whom models continued in production through 2011), and senior citizens, the...
The Best Used Cars to Buy if You Live Close to the Ocean
If If you live close to the ocean, your vehicle is going to be far more vulnerable to rust than if you lived further inland. And the fact is, when it comes to resisting rust, not all vehicles are created...