Finally completed my first job on my '98 V70 T5 wagon last week by doing the crankcase ventilation system. The car started up fine and ran great although CEL stayed on. Ran out of time to work on car (also wife getting antsy to get the car back) so I had to have local garage do the axles. Mechanic calls and tells me that he had trouble starting the car and that it kept stalling out - pulled codes and read 0243-turbo waste-gate solenoid fault and said that I probably needed a new MAF sensor - so he left the MAF disconnected when I picked up the car!?
I guess I just needed to remind myself why I do my own work!!

Anyway, the car idles rough with MAF disconnected as one would think so I re-connect the MAF and it starts right up and runs just fine. Took it for a drive and seemed to run fine then I took it out and opened it up and turbo kicked in fine with the usual lag but the boost seemed OK. I made one stop and then it bucked once a mile down the road and stalled out and couldn't re-start it so I pulled the MAF connector and it started up and drove home that way. I checked out the signal from the MAF and seems fine so I re-connected it and drove just fine for a week with 'good' boost power(don't have a boost gauge yet). Now it is doing the same thing - intermittently losing power and/or stalling out. I tried a junk yard MAF and some cleaner but that didn't help.
Went to local auto store and read the codes again - this time it gives codes 0243 and 0102 indicating MAF or vacuum problem. I checked all hoses and haven't found any leaks although some are getting dry and the line going from the waste-gate pressure regulator to the vacuum tree that has some type of check-valve is cracking and probably needs replacing. I'm new to Volvos but I'm thinking that the waste-gate may be the problem although it could be both MAF and waste-gate. I've seen a reference to the boost control solenoid somewhere but I'm not sure where that is located? Anybody have any ideas on troubleshooting this type of problem?
I am also looking for a good theory of operation on how the Volvo turbo system works including TCV, BCV, waste-gate and associated components if anyone has any good links.

Thanks and excuse the wordy post above - I'm not experienced in turbo charged vehicles!

 

There is a TSB out there for the MAF sensor. It involved cleaning the connector (not the sensor) with contact cleaner, bending the cable back 180degrees and zippy tying the cable to the air pipe.

Ive searched for a pic of this to no avail. I'll try and snap a shot of mine. Its worth trying this first.

Theres a vacuum elbow that buried on the pulley end of the engine, attached to the inlet manifold. Its buried behind the power steering pump. They break all the time and often cause vacuum issues. The wastegate is controlled by the solenoid by pulsating quicky between the vacuum and pressurized sides of the system to maintina the desired boost level.

 

Thanks for the quick reply.
That's a good tip about the MAF sensor - how did you come across the TSB? I looked up the VADIS for this model and I may have found a torrent file that will work - is that a good source for TSB's?

I did notice that the MAF connector cable looks like it was probably zipped to the intake hose at some point. I will try the connector cleaner and maybe I'll get lucky! I did clean the sensor wire itself with the MAF cleaner - probably a waste of money but you never know. The power loss was more regular driving it today - I may just have to bite the bullet and get a new MAF for $165 -ouch!

Do you have any ideas where I can find more technical help concerning the apparent waste-gate actuator problem? The only vacuum connection I'm aware of on that side of the engine is the one that connects the back under side of the intake manifold and runs to the PTC nipple on the turbo intake side and I made sure that was well connected when I installed the new hose from the PVC kit. Is there another vacuum connection beside this one?