Cylinder Misfire Sigma Engine

[PortRS]

The check engine light on my 310S comes on when I start the car, then dims as I start driving. The OBD reader gives me “Cylinder 1 Misfire Detected” (and “Fuel Volume Regulator A Control Circuit Low” and “Left Front Wheel Speed Sensor A Circuit High”). 
 

I checked the exhaust runners temperature with an infrared thermometer, and the first one (closest to the bulkhead) is about 20 degrees cooler than the others. 

What should I do next? Thanks for your advice. 

[Dave W]

I would check fuel pressure at the fuel rail. How old is your fuel filter? You could also swap fuel injector location and see if the misfire moves with the injector.

[11Budlite]

I'm pretty sure there's no fuel filter, just a sock in the tank. Adding to what Dave said, I'd also check compression and spark on all cylinders to get a good baseline. Check the spark plugs and see if the cylinder with the lower temp looks the same as the others. It could be something as simple as a bad plug lead or spark plug, or a bad connection at the plug or coil pack. Just an FYI: Sigma engines should be wasted spark with 1 and 4 firing from one coil pack and 2 and 3 from the other coil pack. Cylinders are numbered 1,2,3,4 from front to rear.

[MV8]

Since I don't know the history, aside from normal troubleshooting, I'd clear the codes then note when/if they reappear and check right after they do. Each error has a number. "Fuel volume regulator" sounds like a p0003 for direct injected engines that have an engine driven high pressure pump as well as a typical pump in the tank and a inline filter between them. The sensor would be integral to the engine pump.

[slowdude]

Echoing others as I recently went down the rabbit hole on this.

 

Check easy stuff first, resistance through plugs and coils, making sure that it's sparking.

 

Then check FPR and fuel pump. I don't think it would be fuel pump because all cylinders would be impacted.

 

I'd lean more towards measuring the resistance of the injectors, it's possible an injector is gummed up.