Hi in need of some suggestions :/
Ive got a vectra c with the z22yh engine, runs fine if driven steady and avoid using more than 25% throttle go over this and it will only let you rev to 5.5 k and start missing eventually bringing up engine misfire code on various cylinders ive had p0301 p0302 p0303 and p0304 all at different times.
Drops to 3 cylinders when code is present but even if cleared while engine running it goes straight back on 4
ive cheked fuel pressure and im getting aprox 600 psi on idle and 1600 on higher revs.
weird thing iv noticed is throttle position on live data wont go past 40 -50% after i cleaned it out it showed 60-70% is that normal?
ive tried air filter, plugs, coil pack, regulator, fuel filter, cleaning everything i can think of - egr, maf, inlet manifold, all breather pipes
any suggestions on what to check cos im running out of ideas