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1996 850 Turbo No boost. RESOLVED

Help, Advice and DIY Tutorials on Volvo's P80 platform cars -- Volvo's 1990s "bread and butter" cars -- powered by the ubiquitous and durable Volvo inline 5-cylinder engine.

1992 - 1997 850, including 850 R, 850 T-5R, 850 T-5, 850 GLT
1997 - 2000 S70, S70 AWD
1997 - 2000 V70, V70 AWD
1997 - 2000 V70-XC
1997 - 2004 C70

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Ubbm
Posts: 38
Joined: 25 November 2010
Year and Model: 850 Turbo 1996
Location: New Mexico, USA

1996 850 Turbo No boost. RESOLVED

Post by Ubbm »

Just completed a valve job and the car ran great except the boost was a bit weak. Gradually got to be no boost. But the car was otherwise driving well, no drivability problems at all.
Then the TPS went out. Replaced it and it was driving well again. Then the MAF went out. Replaced it and it was was driving well again. Then the rear O2 sensor went out, replaced it. All above were OBDII codes. Now it is driving like crap.
No CEL this time - No codes. Hesitates from a start and hunts at 45mph. So this is a separate problem to the lack of boost.
Re: the turbo....
I have checked the turbo, it spins and has no end play.
I have replaced all the vacuum hoses, in fact I installed an IPD TCV and CBV and got the tool to set the actuator adjustment as well.
It was bad enough trying to trace the boost problem, now trying to trace two problems it is driving me crazy. Starting to have turbo nightmares!
What have I missed? Anyone have similar problems?
1996 850 Turbo Sedan
2002 VW Passat 4-Motion (wife's wheels)
1984 F-150 4wd.
Previous interesting vehicles:
1974 Ferrari Dino 246 Spyder
1973 Bentley S Sedan
1956 Jaguar XK140 Roadster
1929 Salmson (first production DOHC engine)
1926 Darracq Tourer

jblackburn
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Posts: 14043
Joined: 8 June 2008
Year and Model: 1998 S70 T5
Location: Alexandria, VA
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Post by jblackburn »

Loose clamps!!! Check them all the way down to the intercooler and back up, giving each hose a good, solid tug.
'98 S70 T5
2016 Chevy Cruze Premier


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matthew1
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Posts: 14466
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Year and Model: 850 T5, 1997
Location: Denver, Colorado, US
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Post by matthew1 »

Vacuum hoses +1. Also check the TCV routing. An experienced Volvo tech put the hoses on the new TCV in my 2004 V70 R incorrectly a few years ago during a mega 90k service, and it was a strange shakedown drive, let me tell you.
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1998 V70, no dash lights on

1997 850 T5 [gone] w/ MSD ignition coil, Hallman manual boost controller, injectors, R bumper, OMP strut brace

2004 V70 R [gone]

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Ubbm
Posts: 38
Joined: 25 November 2010
Year and Model: 850 Turbo 1996
Location: New Mexico, USA

Post by Ubbm »

I found a hole in one of the intercooler hoses. That simple. But thank you for making me carefully inspect each hose!
1996 850 Turbo Sedan
2002 VW Passat 4-Motion (wife's wheels)
1984 F-150 4wd.
Previous interesting vehicles:
1974 Ferrari Dino 246 Spyder
1973 Bentley S Sedan
1956 Jaguar XK140 Roadster
1929 Salmson (first production DOHC engine)
1926 Darracq Tourer

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