850 Turbo limited Boost/Missing

calbrit01 · Post by **calbrit01** » 25 Nov 2009, 20:24

Had the fuel pump and alternator replaced, and about a week later suddenly started loosing boost - seems ok around the low revs, on the vac gauge ok up to the 50% mark, then although gauge goes up there is no more accelleration. It also does not start well and often missess horribly after starting, and then seems to pick up and is fine. I pulled the following ODBII codes: 172,326,331,1310,300. 326 has been around for a while, and is probably the harness mod required but I am not sure what is causing the others - I have checked all the Turbo in and out hoses, and they all seem fine - only other thing I can think of is the catalytic converter? Any other ideas?

Cheers

SAL

FCPEURO · Post by **FCPEURO** » 26 Nov 2009, 07:56

More then likely, you have a vacuum leak somewhere. I would check all the vacuum lines to make sure none of them have come loose then the alternator was replaced.

calbrit01 · Post by **calbrit01** » 26 Nov 2009, 08:52

Ok thanks, that was the first thing I looked at but I may have missed one. The car was running fine until about a week after returning from the shop though, guess one could have come loose/deteriated. One of the large lines connected to the vacuum tree came apart in my hands, I previously replaced most of the others with silicon lines. There was one line under the left hand, drivers side fender which was connected into a tree branch that was blanked off, I reconnected it to an open branch but it made no difference.
BTW Anyone got a clearer line diagram than the one in the manual in the forum?

Thanks

SAL

FCPEURO · Post by **FCPEURO** » 27 Nov 2009, 09:27

I think the one in the forum is the best on that I have seen.

The only other thing that I could think of that could be causing the issue that you are having is if the new alternator has a bad or an incorrect voltage regulator in it. One way to check would be to see how many volts the car is charging while it is running.

calbrit01 · Post by **calbrit01** » 29 Nov 2009, 19:59

Ok, Ill check that, but its odd that the missing only occurs occasionally after starting and then picks up from there. For those of you who remember carburetters with chokes, just feels like starting with either too little or too much choke as it picks up after a few minutes - what causes the boost issue I am not sure, but I could imagine it being a blocked Cat but I have no idea how to test it. Got to say it doesn't "feel" electrical. Electical issues tend to be either always there or intermittant / and/or weather releated - now as we have no bad weather to talk of here in southernern California, its not that. It could be a fuel delivery problem, not enough getting through when you gas it and sometimes missing when starting - Looks like if i dont find it soon i'll have to send it back to the Volvo mech, which I am not keen on as thats always costly

calbrit01 · Post by **calbrit01** » 01 Dec 2009, 12:56

Ok, Alternator checkes out fine, although I did have a dead battery this morning, so need a new one, but that wont cause this issue. Vacuum lines all look fine to me. Still fishing for ideas