AH astra 1.8L code (p0303)

[Timsim9000]

hello everyone can someone help me my astra has recently had a bad missfire code (p0303) and ive just changed the spark plugs and the coil packs and it’s done zero difference. Hoping someone has had the same problem. Any help would be appreciated.

All it says on my cheap scan tool is cylinder 3 missfire. Is it possible it’s fuel pump ? Or would it say fuel pump if that was the problem..

 

[grey_hawk]

If it's only cylinder 3 and you have changed the coil and plug, how about the plug lead? (if used)

 

[the_boozer]

do you have a noid light does it have an injector signal on number 3 does the injector work? If it was low fuel pressure wouldn't it be missing on all cylinders?

 

[lmoengnr]

Which 1.8 engine, Z18XE or Z18XER?

 

[Timsim9000]

Which 1.8 engine, Z18XE or Z18XER?

I believe xE not quite sure what the difference are to be honest.

 

[Timsim9000]

do you have a noid light does it have an injector signal on number 3 does the injector work? If it was low fuel pressure wouldn't it be missing on all cylinders?

I’ll definitely look into that cheers for the suggestion

 

[lmoengnr]

I believe xE not quite sure what the difference are to be honest.

AH series 1 were XE's, series 2 were XER's. The difference is the XER's had VVT on both camshafts.
The VVT phaser on the intake cam was a known problem, it fell apart internally.

 

[Timsim9000]

AH series 1 were XE's, series 2 were XER's. The difference is the XER's had VVT on both camshafts.
The VVT phaser on the intake cam was a known problem, it fell apart internally.

Yeah no worries thank you, it’s a series 1 Xe

 

[lmoengnr]

Yeah no worries thank you, it’s a series 1 Xe

Wont be the phaser problem then. A fuel pump problem wouldn't be related to a misfire in #3.
You replaced the plugs with new ones? New coil pack?
Disconnect the harness plug to #3 injector, with a multimeter check the resistance of the injector. There should be some resistance. An open circuit would mean the injector is fubar'd.

 

[Timsim9000]

Wont be the phaser problem then. A fuel pump problem wouldn't be related to a misfire in #3.
You replaced the plugs with new ones? New coil pack?
Disconnect the harness plug to #3 injector, with a multimeter check the resistance of the injector. There should be some resistance. An open circuit would mean the injector is fubar'd.

Ok thank you for the suggestion i will try this. Yes all new plugs and coil pack