159 2.4 Turbo boost pressure drop and noise
I've been trying to get to the bottom of this issue for ages and wondered if anyone had any ideas.
My 57 plate 210 (85k) is behaving strangely and always has done since buying the car 18 months ago.
Setting off under normal acceleration in first gear the boost pressure climbs steadily up to around 1 bar or so but as the pressure climbs performance seems to be somewhat muted like the car is being held back, then all of a sudden the boost gauge drops like a stone to around 0.4 bar the car takes off again with a jerk and boost pressure begins to climb a second time but this time is maintained and holds steady.
I've also noticed that in the first phase of the boost pressure building but the car not really going anywhere if I put the clutch in to change to second before the boost gets chance to drop I hear an odd "ch ch ch ch chhh" kind of noise like some kind of build up of pressure is escaping somewhere.. Is this compressor stall??
Things already done are as follows:
- EGR fully blanked off
- Swirl valves fully blanked off in manifold and manifold cleaned
- Turbo has been reconditioned
- Vacuum solenoid tested and replaced just "in case", vacuum pipes checked and actuator rod observed
- MAP sensor cleaned out
- All turbo hoses pressure tested for leaks
- MAF sensor temporarily disconnected and problem remained
- FES showing actual boost regularly far exceeding desired boost but no boost error codes ever being logged
Only thing left now that I can think of is the DPF. I'm seeing Anti Polution Filter clogged messages quite often at the moment and my economy has taken a dip recently too to around 22mpg (90 percent of my driving is town driving).
Can a clogged DPF cause turbo issues? FES said my DPF was 28 percent clogged then I ran a forced regen and that figure went up to 69 percent!
Should I be drilling this badboy out??
Thanks in advance folks!