Plenum Chamber Removal Z32 v6

[CDUB]

I have an 04 Vectra C 3.2 V6 (Z32) Petrol auto / aftermarket LPG conversion (fitted in 06) auto.
To remove LPG injector gas unit, i need to remove the plenum chamber to get to the injector bank closest to the bulkhead.

As the vehicle has done 41'000 miles is it best to change the spark plugs? I was thinking of installing Denso Iridiums IK20'S.

Is there any way to check that the coilpacks and spark leads are working within spec?
The reason i ask is, i seem to be getting that mid range flatspot that other owners seem to have. I did the airbox mod (with new K&N filter )fitted a couple of weeks ago but this has no effect in resolving the flat spot.

When i remove the plenum chamber will i need to replace any gaskets or seals if so which ones?

Regards
CDUB

[Gsi3.2]

there is no way to check the coilpacks are working' within spec's ' as they are a solid state , sealed for life module.. and there are also no spark leads.. the packs sit directly on top of the plugs..if there are no fault lighhts then the packs are fine..

to remove the plenumb, you'll need to remove the black 'ecotec' panel on the top of the engine, that will reveal 5 deep 'bores' which will show you 3 of the mounting screws.. the 6th one is under the intake butterfly assy..there are no gaskets to replace, the seals are moulded into the plenumb so be careful not to nick or damage them..

if you are going to all the bother of taking the plenub off, i'd definately replace the sparkplugs while you're there....if that doesn't improve the running then i'd look at fuelling..is the flatspot worse on gas than it is on petrol?

[CDUB]

Thanks Gsi3.2 for replying so quickly.
Its hard to tell since i bought the car it does'nt run very well in general on LPG anyway.
Took it to my local LPG bloke who highlighted one of the LPG injectors was not working correctly (just running on 5 cylinders). Hopefully once i change the old LPG injector pack for the new one i should be able to run on gas.

If i damage the moulded seal by mistake what do i use to repair or replace it?