Z22YH Misfire / Low Power

DavidLaughton

I hope someone can help out as I am just about at the end of my tether.

My 04 Signum 2.2 direct died with the engine management light on - managed to restart but went into limp home mode. Fault was originally diagnosed as faulty high pressure fuel pump - replaced but still no good. Next, coil pack and plugs replaced, still no joy but at least car more driveable but misfires under load and anything other than very light acceleration. Strange though, if the car is driven very gently, the engine management light stays off and I have done a few hundred miles like this but as soon as you ask for a little more power, the engine starts to misfire as if on 2-3 cylinders and if you try even harder, the engine management light stays on.

Fuel pressure regulator was the next suspect so now this replaced also but fault still remains. I am always being told by the garage the problem is low fuel pressure in the common rail but I am now sceptical as all the common failure parts have been replaced.

Does anyone have any ideas?

jwalker

If the eml is on, get the error codes read to find out why first rather than having the garage replace parts at will

DavidLaughton

HI,

Thanks for your reply - the garage acted on the error codes they found which indicated low fuel pressure (didn't make a note of the error codes though) in the common rail but having replaced pump, fpr, coil pack and plugs as a precuation since a misifre error code was also present, still the car is not right. Only two things I can think of that are left now are the in tank fuel pump and the fuel pressure sensor but having spent the thick end of £600 so far I am understandably reluctant to spend more unless I have a good chance of getting it right.

Perhaps I should invest in a diagnostic kit to see the codes for myself - anyone know of a reasonable one?

Thanks

Dave

rushy

What make is your new fuel pump as it still sounds like that and its a very very common failure for the z22yh.

DavidLaughton

Hi Rushy,

Thanks for your reply.

Not too sure about the actual make of the pump but I remember it was in a genuine GM box with the correct part number and it was supplied by vauxhallworldparts who I would assume would be selling pukka units.

Thanks,