My Chrysler wagon "runs on" after I turn it off. What's going on?

Dear Car Talk

Dear Car Talk | Jan 01, 1997

Dear Tom and Ray:

I have a problem with my 1984 Chrysler station wagon. It will "run on" after I turn it off. And on the road, it will continue to go fast even with my foot off the gas. Can you give me any idea as to what the problem might be? -- Nell

TOM: Yours won't stop running, Nell? Gee, most people who write to us about this car have the exact opposite problem.

RAY: You probably have a Mitsubishi 2.6-liter engine with the Mikuni carburetor. This carburetor has two throttles, and its secondary throttle is prone to sticking.

TOM: My guess is that most of your driving is around town, right? How do I know? Well, you're driving an '84 Chrysler, so you wouldn't dare go far from home! And when you drive around town at slower speeds, you're only using the carburetor's primary (slow-speed) throttle. And because that secondary throttle isn't being used for days -- maybe weeks -- at a time, a lot of gunk builds up in there.

RAY: Then, on those rare occasions when you do take it out on the highway, the secondary throttle sticks in the open position. And when you slow back down, that secondary throttle stays open and continues to pour in gas and air.

TOM: And that's why the car accelerates without your stepping on the gas, and why it keeps running even after you turn off the ignition.

RAY: You need to have this carburetor cleaned out, Nell. Maybe you can find a mechanic who went to MIT -- the Mikuni Institute of Technology.

Get the Car Talk Newsletter

Got a question about your car?

Ask Someone Who Owns One