2007 awd s60 T5 erratic boost

docbipe · Post by **docbipe** » 17 Mar 2018, 15:25

Learning time again!
My boost is all over the place and making the car perform eraticaly. When you first step on the gas it will surge like it really wants to go, falls over, then starts to accelerate better as it gets going. I put an external gage on it to see what is happening, and the results are when just getting going there is about 2-5lbs. of boost even when it falls over. When it picks up again it is close to 8-9 lbs. When it starts to run normally it gets as high as 16lbs!
If you feather into the throttle and hold about 3500 to 4000 it will climb to almost 20 lbs and accelerate very well!
I have a feeling the boost control is kaput but I still feel there is more involved her than what I am seeing. I would like some input before I drop money into a new turbo and such. The car only has 124k on it.

Post by **matthew1** » 17 Mar 2018, 15:40

A new turbo is about the 10th thing you should try.

First up would be vac lines and intake hoses. Look for cracked elbows on vac lines, cracked vac lines, and the big intake hose either collapsing under boost from soaking in spit-up oil, or slipping off the intake manifold.

There are dozens of great threads about lost boost here.

Post by **erikv11** » 17 Mar 2018, 19:42

In addition carefully checking for and fixing all hoses for vacuum and boost leaks, you could test the CBV diaphragm.

docbipe · Post by **docbipe** » 23 Mar 2018, 14:20

Hoses and such are all in good shape.
I forgot to note one possibly related symptom, when started cold the exhaust sound cycles between being muffled to sounding normal.
ANYWAY, I bought an IPD TCV and it acts much more normal. When it takes off it keeps going rather than falling off, etc. 12 lbs seems to be max boost and 7-8 lbs normal under normal acceleration. I have NEVER seen a vacuum reading.
The car is much more docile that it has been, with the boost all over. I think the deed is done.