Jerking, jumping

[whenyouaintgotnobills]

So I've got a problem of my Astra MK4 jerking and jumping when moving from a standstill and when changing gears. Apart from that if I floor it in neutral at idle it will sorta want to cut out at first (RPM will slightly fall and the car would jerk), only then the revs will raise instalty.

OPCOM connected - no codes on engine.
Coilpack replaced - no change.
Sparkplugs replaced - no change.
EGR blanked off - no change.
Chain - checked, tight AF.
Throttlebody - cleaned.
Inlet manifold - sprayed down with carb cleaner.
Checked surroundings of inlet manifold for any air leaks - negative.

BTW, It's an LPG conversion, I get the same jerking on petrol or on LPG. Only difference is that it jerks ALOT more on LPG.

Read on some forums that the cause might be a blocked CAT, altought she accelerates quite good.

Also my left front hub gives an error (Speedo sometimes doesn't work, ABS/ESP cuts off) - can that influence the jerking?

Suggestions?

 

[Johnss]

Opcom live data in studio.

 

[vocky]

might be worth taking the downpipe off and seeing if anything looks amiss with the cat, you might even get away with just unbolting the mid section and looking into the cat

 

[whenyouaintgotnobills]

Gonna remove the precat soon, might aswell check it

 

[Johnss]

First thing spotted:


Try to look in this direction.

 

[whenyouaintgotnobills]

but it shows readings on the TB percentage that it's fully opened. What's the link between TB percentage and position?