hi all i have a superb 1.9 tdi awx and it has developed a intermitent shudder during acceleration i first thought it was the dual mass flywheel so i fitted a full clutch and flywheel kit but it was still the same ive allso changed the injector loom and fuel filter i looked at the cam when i had the rocker cover off and that looked ok when it randomly happens and you then stop it feels like its idling on 3 cylinders for a few seconds all the power is still their and theirs no fault codes the car has done 138000 miles i suspect a injector but ifso how can you tell which one has any body come across this before. thanks

VCDS log will show you injected fuel quantities and adjustments. So if one is quite a bit off that's you injector. Perhaps an injector O ring seal to the head? Do you have air in diesel? Idle it and see if bubbles evident unclear diesel line.

Tandem pump not feeding enough pressure to the PD injectors?

thanks for your reply i am going to try a tandem pump next then a tank pump if i have no luck it ran perfect tonight on my 20 mile journey home yet ran terrible yesterday it was like it had a bent drive shaft on hard acceleration its very intermittent its got me puzzled i did find the one way valve on the fuel filter t piece was stuck open a few weeks ago i freed it off and have checked it since and it always seems ok i am tempted to try a new one anyway incase its sticking intermittently.