1997 850R Stumbles on Boost?

Red-Sled · Post by **Red-Sled** » 04 Dec 2013, 11:04

Hi,
I have a stock '97 850R (except the 16" wheels) with 135,000 mi on it. I recently took out of storage and put back on road. Car driven very little over last 5 years. Had independent Volvo mechanic check it over and freshen up maintenance, essentially Stage 0 stuff. Using R as daily driver now 100 mi/day.
Anyway, car has started to stumble on acceleration at about full boost. I recently disconnected battery and discharged car side to ground thinking ECU reset. I also put bottle of injector cleaner in tank. I probably didn't reteach ecu properly if that could be cause for stumble. Car also seems to lug around 50-60 mph and 2000-2500 rpm not in boost. Don't recall if this was normal.
Possible causes and solutions for Stumble?
Thanks much

Post by **jblackburn** » 04 Dec 2013, 11:14

What plugs are in it? Stumble at high RPM is usually blow-out on these cars - caused by using the wrong plugs for the application.

Car also seems to lug around 50-60 mph and 2000-2500 rpm not in boost

4th gear lock-up is around that speed. It takes a semi-hard press on the gas to get a downshift.

Post by **rmmagow** » 04 Dec 2013, 11:31

Check the intercooler connection at the bottom, really check it. I always thought mine was tight, but in reality once I tried to pull it off, it came off very easily. Are you running old gas in it? Maybe give the MAF a squirt of cleaner too.

Post by **rmmagow** » 04 Dec 2013, 11:44

Check your air fiter too. My truck, which sits for weeks at a time, started running pretty bad. Turned out some critters built a condo inside the cleaner.

Post by **precopster** » 04 Dec 2013, 14:44

At this age if the original leads, cap and rotor are fitted this would be another likely cause.

White powder marks on them are a sign they are arcing.

Leads are date stamped if they are Bougicord. Take a look and see if their build date is a match to the car.

Red-Sled · Post by **Red-Sled** » 04 Dec 2013, 18:52

Plugs, wires etc are all oem or better. MAF could need attention, i don't know.
Most likely vacuum leak, right? Lines are old, dry, cracked so.......
where can I get a "kit" with all the vac hose sises I need, and adapter fittings if any etc?
if no kit anyone have a parts list? I wouldn"t mind replacing all hoses.
thanks..

Post by **Ozark Lee** » 04 Dec 2013, 20:12

Stylin Motors used to have a silicone hose "kit" which 3 or 4 different diameters of bulk hose (4mm, 6mm, and 8mm). As far as I know Stylin Motors is no longer a going concern and you still needed to cut things to length with their kits, they weren't pre-cut. Gates makes bulk metric diameter silicone hoses or you can just replace them with the less expensive rubber hoses. NAPA should either have them or be able to get the Gates hoses for you. Even Volvo will just sell bulk hose and let you figure out the length.

The only problem I had with the silicone hoses was finding correctly sized spring clamps. The silicone hoses have a smaller outside diameter than their rubber equivalents and I wound up buying clamps that were either too small or too large and then I bent them until they conformed to the hoses enough to hold them in place.

...Lee

Post by **shaker_chi** » 04 Dec 2013, 21:10

Do you get a check engine light? Any misfires? If not, then I would guess a vacuum leak somewhere. Whenever I have the same issue my CEL light goes on or flashes indicating multiple misfires. I have an n/a 850 and 2 turbo s70's and the turbos are very picky about their spark plugs. I would only go with O/E.

socompsp · Post by **socompsp** » 04 Dec 2013, 23:07

did you have the fuel filter changed? how much gas was in the tank when it sat? you can goto a parts store and get the vac hoses for your BCS/tcv. i think just those three lines may help substantially. you aso should consider doing the CBV vac line at the same time. if that hose is starting to weep out air, that valve could be leaking boost on loaded conditions.