Hi Scotty I have a 2003 Ford Focus ZX3 and I'm having a couple issues, when I get to about 50 MPH my check engine light comes on and starts blinking. I scanned it and I got a few OBD codes, P0301, P0316 and P0171 came up and I checked em out on Alldata to see if I could narrow down the issue. I've come to the conclusion that I have bad or clogged fuel injectors but I'm just not 100 percent sure and I don't want to throw more money at this than I have to. The thing is, this issue didn't arise until after I put my car on the lift at work and degreased and sprayed out the underside of the engine bay. Could I have accidentally shorted a sensor or clogged something by doing so? The other issue is my temperate gauge stays at the correct mark for operating temperature at idle but when I start driving I goes to cold and stays that way until I sit at idle for a few minutes. I'm at a loss on what to do and some insight would be greatly appreciated because this is my daily driver and I can't afford another car.
Could be that the thermostat is stuck open. If you got water in the temperature sensor connection, it could be sending the wrong signal to the ECU causing the misfire code.
Could that also cause the thermostat valve to be stuck open?
Not very likely. A fail safe thermostat may have been installed in the vehicle before you owned it and broken in the open position causing the engine to run at below normal temperature, signaling the ECU to produce an overly rich mixture.
If you go to the misfire troubleshooting in our FAQ, there are videos about testing fuel injectors.
OK so I pulled out the spark plug from cylinder 1 and switched it for the spark plug in cylinder 2. There seems to be what looks like excess fuel being dumped into cylinder one, but for some reason the system lean code didn't come back after wiping the codes and testing it again.