Porsche 914 runs rough

I recently bought a 1974 fuel injected 914. It runs OK for the first 5-10 minutes but then starts to run very rough and lacks power. Any thoughts?


I would start with the ignition system. Plugs wires, rotor cap coil etc. Next I would check the fuel pump pressure and volume How are the fuel and air filters

You need a Porsche 914 website like http://www.porsche914.org/ or http://www.914club.com/bbs2/index.php I remember that those cars had rather finicky injection systems, even when they were new. They can’t be much better 34 years later.

You definitely need a manual, it it runs well while cold I would check the temperature sensor and the connection to the sensor first. I permanently solved those types of problems by installing a pair of webers on mine.

Also, do you know when the valves were last adjusted?

I’ll go along with Craig on this one about checking the valve adjustment; a rather regular event. At least if proper procedures are followed.

Another possibility is a faulty temp sensor which can be a common problem.
If the car were mine I would run a compression test as step no. 1. It’s better to make sure the mechanicals are good (hopefully no tight valve problem) before tossing parts at it.

Should have added that it should also be checked for intake leaks which can be a real problem.

Thanks to all for your feedback. I’ll be working through your suggestions as time allows.


I am not sure about this year. A lot of early injection systems had a thermotime switch that kept the start injector running a short time after the engine was started. If this is not turning off that injector the engine will run excessively rich once the engine no longer needs that fuel.

Just an idea I remembered