check your fuel pump. that seems to be a possibility.

 

Hello guys - new here and I know this is an old thread but I have been fighting the exact same surging symptoms under full power for some time ('04 S80 T6). New fuel pump did not fix it. I'm not throwing any codes. I was all set to try the TCV until I read this thread. Anyone else have some ideas for me? Thanks!

 

Welcome. I guess we can start with asking what you have tried. Just the fuel pump?

 

Thank you. We replaced the fuel pump not too long ago because it had a slight leak. The problem was the same before and after. I talked to IPD today and they said 1) fuel pressure problem (not necessarily the pump) and 2) overly sensitive knock sensor (I guess they've seen this before). My local mechanic (Volvo specialists and highly trusted) don't want to go parts swapping without any codes showing. I can't seem to talk them into spending some of my hard earned dollars on diagnostics. I'm going to let the dealer take a look and make sure all the sensors that were on recall have been replaced. It isn't likely I'll let them spend any of my money though based on my prior experiences with them while the car was under warranty.

 

I'm not sure what this hose connects but there is a metal pipe containing 2 or 3 hoses, one of which is a large vacuum hose that was leaking at the a fitting. Hard to see I guess as it threads down behind the engine. My local Volvo shop couldn't figure it out (?) and actually directed me to the dealer. So my car now goes like it should and I had to find a new Volvo shop...