Unfortunately the judder is a classic problem and it is not likely to be something simple as the simple things are actually pretty reliable these days. The greater probability is inlet carbonisation and detonation. This doesn't mean you don't check the plugs but it does mean changing them without finding fault with the old ones is just not doing a proper job.
Dealers have to run a mile from cars with these problems as Citroen don't give any carte blanche to fix this problem on their account and the dealer is the one left with the customer to placate.
I think that BMW or Citroen the engine designer and builder need to be forced to man up and admit that these were first gen GDI turbo engines designed and proven to produce 130hp from a 1.6 turbo but with the higher output 155 and 200 hp versions the greater valve duration caused unintended carbon build up very quickly that does eventually cause detonation. The consequences of this would be financially unattractive though to say the least and I can't be certain they actually have worked out how to fix the problem. There seem to have been a few variations of the cylinder head cover PCV system to try and improve this but ultimately not sure this in itself is a cure or just a workaround to avoid the worst cases only.
It is becoming increasingly likely that as the power outputs have been increased on the BMW prince GDI turbocharged engines the increased inlet valve opening duration and lift can cause excessive carbon build up in the inlet tract. The carbon build up can be easily proven with a fibre optic inspection lamp pushed down the inlet tract.
Dealers have to run a mile from cars with these problems as Citroen don't give any carte blanche to fix this problem on their account and the dealer is the one left with the customer to placate.
I think that BMW or Citroen the engine designer and builder need to be forced to man up and admit that these were first gen GDI turbo engines designed and proven to produce 130hp from a 1.6 turbo but with the higher output 155 and 200 hp versions the greater valve duration caused unintended carbon build up very quickly that does eventually cause detonation. The consequences of this would be financially unattractive though to say the least and I can't be certain they actually have worked out how to fix the problem. There seem to have been a few variations of the cylinder head cover PCV system to try and improve this but ultimately not sure this in itself is a cure or just a workaround to avoid the worst cases only.
It is becoming increasingly likely that as the power outputs have been increased on the BMW prince GDI turbocharged engines the increased inlet valve opening duration and lift can cause excessive carbon build up in the inlet tract. The carbon build up can be easily proven with a fibre optic inspection lamp pushed down the inlet tract.
Originally posted by Gazski66
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