C4 1.6 e-hdi Turbo Underboost Fault P0299

[southwea1976]

Hey all, long winded build up to this but here goes:

Have a 2015 Citroen C4 1.6 e-hdi with a turbo under boost fault.
Car was parked up for a few months, went to run it and it was rough, Ran it for about 70 miles next journey and it dropped an injector, replaced the 4 (as recommended) and got it coded.
Now it idles smooth and has no misfires etc.
Took it for a run and it felt gutless, no "get going" power!
After a while the EML comes on and when code read it says P0299 turbo under boost although it runs ok and can get up to motorway speeds eventually.
This fault didn't exist before the injector fault, its low mileage and full comprehensive service history.

Removed and cleaned the EGR (Was actually quite clean anyway).
Checked the DPF, ran it out for 100 miles of motorway to push a regen if it needed it.
No problems/splits/damage with the boost pipework and the vacuum pipes are sucking properly.
Actuator pulls in when running and moves up/down when accelerating.
The Turbo it's self spins freely.
Has turbo pressure up to the butterfly valve (top left of engine).
Butterfly valve opens/closes.

Is there anything i could have disturbed doing the injectors?
Have i missed something that may need removing and cleaning?
I am 3 months into this investigation now and rapidly losing faith!

Anything, no matter how obscure you may think might help...

Thanks,
Ade.

[Hell Razor5543]

I would check the cabling for the turbocharger. My C5 (which has twin turbos) lost the ability to run the second turbo (the turbo was spinning properly, but the gate was not opening to accept the added boost). It turned out that a cable had been knocked loose (but not off, so not immediately obvious) from a control unit on the front of the engine (the turbocharger is on the back), so the second turbo was not getting triggered. Once the cable was properly seated the second turbo was happy to join in on the game, and normal service was resumed.

[GiveMeABreak]

Have a search on the Citroen / Peugeot sub-forums for P0299 for plenty of posts on this fault.

[southwea1976]

I will check the wiring tonight, i am going to have to check over everything that has a connector incase i accidentally dislodged something when i did the injectors.
GiveMeABreak it looks like i have already been through everything i can find on the forums with no joy, i can only think it's something simple now :/

[southwea1976]

Does mine have the little filter in the boost/turbo controller?

[admiral51]

If you are referring to the Turbo solenoid Valve then yes it does, a very fine mesh/linen filter. If very dirty will look black and not like a filter

Colin

[southwea1976]

If you are referring to the Turbo solenoid Valve then yes it does, a very fine mesh/linen filter. If very dirty will look black and not like a filter

Colin

Thanks, will trace the vac pipe back to it and have a look, it has good vac so i don't think its going to be that but its worth a look whilst I'm under the bonnet.

[southwea1976]

If you are referring to the Turbo solenoid Valve then yes it does, a very fine mesh/linen filter. If very dirty will look black and not like a filter

Colin

Thanks, will trace the vac pipe back to it and have a look, it has good vac so i don't think its going to be that but its worth a look whilst I'm under the bonnet.

Well this is i believe my turbo solenoid valve (Stock picture) and theres no filter on it, so i replaced it for good measure and still nothing, replaced the actuator too and still nothing, i currently have the DPF off, by god did a LOT of crap come out of that with the cleaning solution! First jet black stuff followed by thick reddish brown stuff the consistency of grease but dissolved as soon as it met water????

[southwea1976]

You're going to tell me this isn't the valve i was looking for aren't you?!

[southwea1976]

Update.

Replaced Actuator, Turbo boost solenoid (VAC valve), cleaned out as much of the egr pipework as possible, removed DPF and cleaned it out, also checked the flow through the exhaust.
Crawled over all the wiring with a fine tooth comb.
Would like to verify the EGR valve but no idea how to make sure its working?

Not showing any other faults or codes other than P0299, and this only comes on if i really labour the engine.

[southwea1976]

Added all the live data it shows if it helps anyone see anything out of place?