Hi Folks, I am struggling with a performance problem on my wife's 1998 V90 (B6304FS2, Motronic 4.4, normally aspirated), and I have put quite a bit of work into the diagnosis to no avail. The car just seems like it has lost a lot of power over the years, and it is now a real dog. Merging onto the freeway is tedious, but the car will come up to speed. Full throttle kicks down properly, but there just isn't the acceleration that the car ought to have. Power delivery under load seems less smooth than it should, but there is no dead miss. The car has never lost power or stalled, but its performance is pretty gutless. (Like our old 244DL / auto; maybe slower?) The car has ~96,000 miles on it. Here is what I know:
• Cam timing is spot on; set with crank lock pin and cam plate. Belt at 70K.
• No codes using Volvo scanner or OBD2
• New coils (all 6)
• Fuel pressure in spec; FFL at 60K
• Air filter is clean; new at 90K
• Transmission seems to be working normally; kickdown works
• Plugs: Bosch copper core; new at 90K
• Fuel economy ~17 MPG in town :(
• I have considered maybe the cat is plugged, but it just doesn't feel like that generally feels. I could loosen the cat at the manifolds and drive it, but I'm not very confident that I will get an answer there.

A friend works at the local Volvo dealer, and he let me use the Volvo scanner that plugs into the OBD2 port. I noticed that the ignition timing seems to run about 9 degrees BTDC at idle, but never gets above about 23 degrees, even at high revs. There was also a line for KN.IGN.RET, which I'm assuming means knock sensor ignition retard. This was variable, but mostly at -9 while driving. I took this to mean 9 degrees of retard, which would explain the low advance. I pulled both knock sensors, cleaned them, ohmed them out (in spec), and re-installed them. The scanner shows numerical values for the sensors, and they rise and fall as they should, and they agree pretty closely. I ran the car with the sensors attached to the harness, but tied away from the engine. The KN.IGN.RET went to 0, and stayed there. I re-installed the sensors, but the total advance still stops at ~23 degrees. I had to give the Volvo tester back, but I have a Scan gauge that will let me monitor many of the engine parameters real time. I just drove the car up a good hill at 50+ mph. Timing was around 15-18 degrees all the way up, even when I kicked it down (RPM >4000) Can someone compare my ignition advance readings to theirs or send me a map? I don't fully understand all the variables that affect ignition timing, so a list of suspect components/ things to check would be helpful. The guys at the dealer are also perplexed, and I can't give them an open checkbook to fix the problem, as it could take many hours at $110/ hour. All suggestions welcome and greatly appreciated. Thanks, Tom. BTW: We live in NM, at 5,000 feet.