I'm still trying to get to the bottom of why my citroen C5 2.2hdi refuses to rev above 3k, 3.5k when warm.

when i rev it it sucks flat the intake pipes but there are no obvious obstructions in the intake, it revs much better with the pipe removed. anything i can check fairly easilly? the turbo is horrible to get to but i have a feeling i need to pull the pipes off it to see if it still spins.

Erm.. Do you have a Citroen software maybe? Just hook it up and look what the sensors are telling the engine. I would try to disconnect the MAF sensor to see if there is the fault maybe. You can hear the turbo if its spinning, or try to squeeze the turbo pipe to the intercooler.

I would suggest that you give it to a mechanic which has the appropriate software to take a look at cars faults that are saved in the modules. Also check the vacum pipes (if your turbo has a vacum controller) for any leaks .. Im not really familiar with this engine or the car just blind guessing here..

Does the car have the same power? Did you actually look at the faults that are stored in the ECU? From what you have told i would bet on a sensor or a minor problem..

i cleared all the fault codes before doing a DPF delete on it, and none have popped up since. I am a mechanic but dont have the Citroen Lexia kit to plug into it, just a cheap bluetooth ELM327 fault code reader and my work has a Delphi fault code reader which can activate some parts and force a dpf regen etc but nothing citroen specific.

i cant hear the turbo spinning and the car struggles to get above 40mph on the road, i disconnected the MAF sensor but that made no difference.

Ok, so the problem started occuring after you did a DPF delete on it? How did you remove your DPF? Did you in any way change your ECU? Does the car smoke? If you cant hear the turbo there is a chance that the car is working in fail-safe program which shuts it off (that would explain the lack of power).

- If you have a vacuum controlled turbo actuator check the vacum pipe
- Check the pipe turbo -> intercooler -> ...

If you did any work with your ECU during the DPF delete do a reflash with a stock map..

I would advise you not to use too much of generic fault code readers since sometimes they can do more damage than good. They sometimes have wrong adress codes for the faults and erasing them can do some damage (i know a guy that erased 1,3 and 5th gear on a SMG tranny with that stuff).

the problem was on the car before i did anything to it, ecuedit did the DPF delete for me, well modified my ecu file which i mapped to it but the car appears to be in limp mode with no fault codes stored or eml lit

Surely sucking the intake pipe flat means there's a restriction in the filter or pipework immediately after it? The rest of the discussion is irrelevant until you've found that restriction.