Q: Drive-by-wire throttle problem

asked by on September 12, 2016

My car has a Drive-by-wire throttle problem. When I am coming to a stop at a stop light or stop sign the engine is doing about 2600 to 4000 rpms. When I depress the clutch the rmps don’t drop. When I shift to neutral the rpms stay at 2600 to 4000 rpms until I press on the accelerator with my foot. Then it drops back to idle. This is an occasional problem that happens. I never know when it’s going to occur. The problem is worse when the engine is at operating temperature. I brought my car to the dealership, and they updated the throttle mapping software. But that is all they have come up with so far. Do you think it could be a sensor in the car? What other ideas do you have?

Hello. The symptoms you describe may be caused by issues with the throttle body or with the idle air control valve. The drive by wire system controls an electric throttle body which feeds the engine air. If the throttle body has any issues, it can behave erratically and cause the high idle symptoms you are experiencing. A possible sensor that could also be producing these symptoms is the accelerator pedal position sensor. As its name implies, the accelerator pedal position sensor detects the position of the gas pedal, so that the throttle body can be opened accordingly. If the sensor has any issues, it can also cause the throttle body, and therefore engine idle speed, to behave erratically. As electronic engine performance symptoms can be difficult to pinpoint, a proper diagnosis is highly recommended.

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

How do I turn on the fog light?
The fog light provides added visibility when you are driving in foggy or misty conditions. To turn on the fog lights, rotate the Fog Light switch (located on the turn signal lever) to the on position.
Headlights not turning on
If both headlamps are not working and the bulbs are in good condition, I suspect the head lamp switch is faulty. The head lamp switch on your vehicle houses several other functions like the turn signals and the cruise control...
Slow leak in oil pan
Hello. Resealing an oil pan is not an easy job for someone who is not an experienced technician. I would suggest that you have a certified technician, like one from YourMechanic, come and replace the oil pan gasket (https://www.yourmechanic.com/services/oil-pan-gasket-replacement).
Steering wheel squeaking, after a sudden thudding sound
Without inspecting the vehicle firsthand, I can only guess as to what might be wrong with your vehicle. The issue would be in the column (https://www.yourmechanic.com/services/steering-column-replacement), steering gear, or even the power steering system. Regardless, the vehicle doesn't sound like...
My a/c intermittently blows warm and cold air.
It is possible that your blend door actuator could be failing and going back to the default position. Many vehicles will default the blend door to heat mode. When the blend door actuator fails, it will automatically revert the door...
Can a bad breather filter located under the PCV valve cause my car to turn off after starting it?
No. You should look at the ignition switch not supplying power to the ignition when it is in the run position. This is the most common cause of stall after starting. The ignition switch supplies 12 volt power to the...
Car is stalling - 1994 Lexus GS300
This may be related to a dirty or faulty idle air control valve. This is a unit that reads the air intake as it is mixed with fuel before entering the engine. This information is then relayed to the computer...
When I put my van into drive or reverse it doesn't move. But while in drive or reverse if I rev up the engine it will start to go
Hi There, This may be a sign of low transmission fluid (https://www.yourmechanic.com/services/transmission-fluid-service) or a faulty transmission control solenoid. As you know, automatic transmissions use pressurized hydraulic fluid to change gears. Every time a gear change is required, the car's computer...
Overheating 335xi, new hoses/no leaks, waterpump is fine, no heat, used stop leak but car sat around for 2 months.
Hi Marc. Thanks for contacting us today. In most cases, if your heater does not produce hot air, then the issue is that the heater core is clogged with debris. Using stop leak products tends to create this problem. It's...

Related articles

What Is Direct Drive Gear?
Direct Direct drive is a type of transmission that allows for better gear shifting within a motor vehicle. Because fewer gears are connecting, the vehicle cruises better at a higher gear. That’s a fairly simple explanation, so let’s talk a...
How Do Rotor Engines Differ From Regular Engines?
Rotary engines use three-sided rotors inside an oblong housing instead of pistons. Rotary engines create lots of horsepower, but aren't as efficient.
Symptoms of a Bad or Failing Cylinder Head Temperature Sensor
Common signs include long cranking time, engine performance issues, and the Check Engine Light coming on.