I have a 1986 Plymouth Reliant K. Yes, It is a piece o’ crap, but it is all I have. I am currently having a problem with it. When it is cool outside it runs great. But when it gets hot outside it starts to act goofy. When I start it, it tries to die and I have to give it some gas. It doesn’t idle smoothly. And it doesn’t like to accelerate. I’m not sure how to describe what it does on a post, but I’ll try. the engine doesn’t cut out or stall or anything. It is like it is trying to accelerate, but just isn’t getting enough power. So it will kind of intermittently accelerate. It will go, the back off, then go, then back off, etc. I have already replaced the plugs and roter, air filter, fuel filter, catalytic converter, timing belt, and distributer. So what would cause this kind of problem and be dependent on the outside temperature?
Sounds like a sensor to me.
I had a 89 Camry with a bad Mass Air Sensor that acted almost identically.
It is Fuel Injected, right?
yes, it is fuel injected. I’ve heard of an oxygen sensor, but what is a Mass Air Sensor?
Mass Air Sensor is located in the intake, the Oxygen Sensor is located in the exhaust.
Mass Air measures the volume of air flowing into the intake. This allows the ECU to control the air/fuel mixture. If the sensor shorts, and sends back a reading of say, 0 cfm, then the ECU will cut back the fuel supply drastically so the engine will not run rich. Massive loss in power. Easy to replace, but expensive. $150+.
The Oxygen sensor sits in the Exhaust Manifold and measures whether the car is running rich or lean. The oxygen sensor can cause some problems, but they are usually more subtle than what you are describing. I would recommend changing it anyway, as they tend to only work well for about 30-60k miles. Cost should be between 30 and 40 bucks.
According to my books, that car would use a MAP (manifold absolute pressure–high-falutin’ way to say “vacuum”) sensor rather than a MAF (mass airflow) sensor. It will have a vacuum hose connecting it to the intake manifold. Check the hose to make sure it’s actually connected and in good shape.
The MAP sensor is probably the prime suspect, but not the only one. The coolant temperature sensor, throttle position sensor, and throttle body temperature sensor are some of the other possibilities. A significant engine vacuum leak could also affect this area.
thanks for all of the great suggestions, but would any of these only be a problem when it is hot outside?
Anything electronic can be heat-sensitive (it’s a typical way they start failing), and temperature sensors naturally change with heat and cold.
thanks gary t. is a MAP sensor expensive? is it easy to change?
Usually not very expensive as sensors go, and usually easy to replace.