Hi all, hoping there's someone who can possibly shed some light on my engine problems. I have a zetec in the car running standard ford ECU and wiring.
A few days ago it suddenly dropped onto 2 cylinders on the way home, I found that it was fine once I was above about 3k rpm and accelerating. Ease off and it was straight back to 2.
Since then I have changed the coil pack and TPS (fault code in ECU). The engine had new leads and plugs 3 months ago.
I have tried unplugging the cam sensor, maf, idle valve, TPS. All seem to be working as expected.
There is continuity between ECU and all sensors. It runs on cylinders 2+3 with everything connected. I disconnected leads 2+3 from the coil and the engine ran on 1+4 instead. Disconnected 1+4 and it ran on 2+3. Connected all back up and I'm back to 2+3 only.
The strange thing is that the tachometer wavers (driven straight from the ECU), if I gently blip the throttle the needle momentarily drops and then recovers to 800rpm. Rev it for longer and the needle doesn't match engine speed going to about 1500rpm, occasionally twitching up to the expected level.
Its got me stumped but hoping there's an expert with another idea?