Kevin G

My 79sc starts extremly hard when the engine is cold. After it does start the engine sputters for the first 5-10 seconds and then sets into proper idle. Once the engine is started, it will continue to start with no problem as long as it doesn't sit to the point the engine is cold. Any ideas on what might be causing this would be greatly appreciated.

Thanks Kevin 79sc

ron mcatee

Sounds like a Head Temperature Sensor. Check that first.

88 Carrera
Spider911

rickc

Check the output on your coil and your cold start circuit.

ChrisB

Sounds like it's running lean. I'd check your cold start injector. If you give it a little throttle while it's sputtering and it dies, that could be the problem.

ChrisB

Just thought of something else. An intake vacuum leak can cause those symptoms too. I'd check specifically around your popoff valve - they commonly are susceptible to that. Let me know how you make out.

Hladun1

There could be a number of things, but here is a very simple but very, very important one. Is your thermotime switch correctly connected?

The thermotime switch is mounted on the left cam chain cover near the engine electrical master plug. It opens your cold start injector when the engine is cranking. It's a switch so you just connect the two wires; wrong! It is internally grounded so one connector is the switch and the other is the heater to turn it off. The red/black wire must go to the switch (0 ohms to ground when cold) and the yellow to the heater (mine is about 60 ohms cold). If you connect it wrong the cold start valve will not open because its in series with the high resistance heater and you will have starting problems.