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98 v70 t5 no boost Topic is solved

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

1992 - 1997 850, 850 R, 850 T5-R, 850 T5, 850 GLT
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1997 - 2000 V70, V70 AWD
1997 - 2000 V70-XC
1997 - 2004 C70

turtle1615
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98 v70 t5 no boost

Post by turtle1615 » Tue Aug 07, 2018 5:05 pm

So on my way to work earlier today everything was fine, had good boost on my guage and plenty of power. On my way home it has no boost and just doesnt have as much power, it runs fine otherwise, no noise or high idle or anything like that. I've checked all my hoses and don't see any leaks. On the interstate if I hammer it the guage will shoot up to 4 psi then falls back down into vacuum even when holding the throttle. In park it builds no boost and stays in vacuum the whole time revving it up. Any ideas? This is my only car I need it running right.



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matthew1
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Re: 98 v70 t5 no boost

Post by matthew1 » Tue Aug 07, 2018 5:27 pm

It’s almost always a hose, and owners often don’t catch it first time looking.
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1997 850 T5, MSD ignition coil, Hallman manual boost controller, injectors, R bumper, OMP strut brace [gone]
2004 V70 R [gone]

turtle1615
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Re: 98 v70 t5 no boost

Post by turtle1615 » Tue Aug 07, 2018 5:31 pm

I'll go over them all again. I've replaced all the hoses with silicon and done a heavy duty tcv. The issue also seems to be causing some harsh trans shifts, it's an auto, maybe related. Not sure.



turtle1615
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Re: 98 v70 t5 no boost  Topic is solved

Post by turtle1615 » Tue Aug 07, 2018 5:42 pm

It was the plastic inlet tube from the radiator support to the air box. It was sucking in when I'd rev it up, removed and drove. Have my boost back and trans shifts normally. Thanks for your help.
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Re: 98 v70 t5 no boost

Post by abscate » Wed Aug 08, 2018 4:51 am

You can’t check boost by revving at idle with stock components. Boost is controllled by the ECU, not rpm, and the ECU requires load To turn boost on.


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turtle1615
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Re: 98 v70 t5 no boost

Post by turtle1615 » Wed Aug 08, 2018 9:20 am

That makes sense. It's all good now. Just gotta get a cold air intake to replace the factory setup



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