A hot topic in the forum at the moment has got our members stumped.
We have had someone wondering why only two of the four cylinders on his 2003, 1.6 Fiesta are firing when running below 3000rpm. When the car runs above 3K it then seems to run on all four.
Before even getting to the forum our member had already replaced the HT leads, spark plugs, coil pack, cam sensor, crankshaft sensor, and fuel filter, all to no effect.
The next suggestion was there could be a block in the injectors or an air leak in the intake system, but apparently not. After checking all was well, still the same problem.
He then tracked the wires all the way from the coil pack to the ECU, ended up replacing two of them due to external breaks but still...the exact same situation.
So the mystery goes on and our member is still after the right answer to get his car firing on all four, all the time.
To check out all his attempts to fix it so far and to give your suggestions click here: http://www.fordownersclub.com/forums/topic/36865-fiesta-zetec-only-firing-on-2-and-3-ive-run-out-of-ideas/