jon_d_h

Right, I have an issue with my car over fueling and running rough so I wanted to test a few things before taking it somewhere. I have a mk2 escort with a 2wd cosworth turbo engine

I disconnected the coolant temp sensor and checked its resistance cold and it's about 4.5k ohms which sounds about right. I checked voltage to it at it was 4.3v. I decided this was correct so plugged back in and now I can't start it at all??!!

I have tested back at the ecu plug between pins 11 and 29 which are the 2 from the sensor and I have 4.5k ohms so it is connected right. I haven't touched anything else, I have tried reconnecting other plugs still nothing. I have a spark and I have fuel pressure but it just doesn't fire!

I did try starting the car with the temp sensor disconnected and it wouldn't start. Could the ecu have gone into some sort of lock mode because of this as I literally drove the car out of the garage, messed with the one sensor and now it won't start at all.

Any ideas?

Thank you

oldford

Voltage to the coolant temp. sensor when disconnected should be 5 volt, not 4.3 volt.
Check what voltage supply you have on the TPS, the map sensor and the intake air sensor. The last one you have to measure when disconnected.

There is no lock mode present in a standard 2-wd cosworth ecu. Everything is cleared when the ignition is switched off.

jon_d_h

Ok, will give that a test this evening, if I have 4.3v supply from all, what does this prove? I can't see the ecu being at fault as it was fine before I touched the temp sensor. Unless one of the sensors is dragging the voltage down

oldford

If "ALL" the sensors only have 4.3 volt, then as you say something is pulling the 5 volt down. Or the ecu is defective.
The problem may be in the wiring loom, you have to check for that too.

jon_d_h

Ok so did some more tests. There is 4.3v at all sensors even when they are all disconnected so I'm assuming there is only 4.3v from pin 11 on the ecu but I can't imagine the ecu being faulty as the only thing I have done is disconnected the temp sensor and now it won't run.

I did try to turn the engine over with coolant temp sensor disconnected which may have flooded the cylinders as it was open circuit. I have removed and cleaned the spark plugs as they were wet with fuel and black but still no different. Would it be worth leaving spark plugs out to dry off? I'm getting a spark on all of them.

All I noticed was that pin 24 was down to eart which comes from ignition module. Not sure if this is correct. Also, the crank sensor switches between 600 ohms and 6k ohms. Does this seem right?

I don't see why it won't even try to start when I have fuel and a spark, I have 12v to all the injectors and they are all approx 4.6 ohms.