My 2001 Focus ZX3 is not running right. Starts fine but has no power and will surge.
1 – New spark plugs. OEM
2 – New plug wires
3 – New/used coil pack
4 – New/ used Air temp/MAF
5 – New PCV and hoses
6 – New fuel filter
7 – Air filter OK
8 – Compression 1 = 169, 2 = 172, 3 = 171, 4 = 168 avg 3 readings
9 – Fuel pressure = 50 avg 3 readings after prime of 20.
10 – Disconnected the exhaust at header to check for plugged cat or muffler
Car will start and idle really well. Try to drive it and there isn’t enough power. It will surge giving power and then lose it again. This happens hot or cold. New spark plugs have dry black carbon fouling indicating rich mix.
check your temperature sensor, sounds like the car could be running in a closed loop making it think the car is still cold even after it warms up hence why its running rich.
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