Hey guys, I seem to have run into a pretty unique problem (struggling to find others that have had the same issue). Basically what happens is that the car starts misfiring really badly above 3000rpm when warm. When the issue first presented itself it was something that would only happen over 5000rpm. But since then the rpm at which it would happen has begun to creep down. When it is really bad it can happen at idle when sitting at traffic and the engine just stops. On top of this the car struggles to start, this issue with starting began at the same time as my misfire issue so I think they are related.

Some notes:
- The car is a 1998 Mazda Familia (same as the protege and 323) and is part of the BJ generation
- The engine is the 1.5L ZL-VE
- The car misfires whether it's under load or just in neutral.
- When trying to start the car the start cranks just fine, it just won't start, pumping the gas pedal sometimes helps.
- I performed a fault code diagnostic and there were fault codes for both the cam position sensor and a knock sensor. I have replaced both of these and the issue still persists.
- I have also replaced the spark plugs, HT leads, coils and battery.
- I have taken the car to a mechanic whose solution was to replace the air flow meter, this has not fixed the issue either.

Any help would be greatly appreciated. I really need to sell the car but won't get much whilst its in its current state.

Cheers

 

Does anyone have any ideas?

 

Sounds like timing (the timing belt) is off one notch or the belt is worn out. You will need to inspect the belt and the belt tension. You can inspect by taking off one or two timing belt covers and doing a visual without disturbing the timing belts or cams etc. Youtube has many videos to explain it to you.