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less boost after wastegate adjustment Topic is solved

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
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This topic is in the MVS Volvo Repair Database » Troubleshooting Low Boost
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jblackburn
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less boost after wastegate adjustment

Post by jblackburn »

From a cold start, drive gingerly under 2000 rpm for 5 minutes. Half the boost level is 5 psi. I borrowed a boost gauge from a friend with an rx7 to help calibrate mine, but really keepin it under 3500 rpm at a bit less than half throttle seemed to do the trick for me.
'98 S70 T5
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Post by Juan62 »

Still confused... Do I pull over at a dead stop and accelerate the car up to 5 psi and hold for 5-7 seconds? or do I drive on normal street fro 5 minutes, then get to highway and accel to 5 psi, then decel to 30 mph../.and repeat this process 4 times, go home, turn off engine for 12 minutes...then do all over again (second time)?
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jblackburn
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Post by jblackburn »

Second one.
'98 S70 T5
2016 Chevy Cruze Premier


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LamboSE5
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Post by LamboSE5 »

Good thread.

I'm surprised that CBV (diaphragm) wasn't in that list of things that could cause low boost.
Now, I'm not as sure (as I thought I was) about my issue being the CBV diaphragm. I have this strange problem with boost pressure. It's like late, fluttery, (or maybe just low) boost. It seemed like something that could stem from a torn or old "hole-y" diaphragm.

It's difficult for me to describe. I made a (very) long post in which this was one of the problems I listed. I'll find it and link (if anybody cares to perhaps...speculate or suggest :) ) to it.

Also, very much related if not the same problem, is; If I press the gas peddle to any specific position, arriving at that position quickly, and then hold it exactly there, I notice that the RPMs go up and over where they seem they should be - because then then they fall below where they should be, and then (if I remember correctly) they go back up and level off somewhere in the middle of the two. :?
Doing the same thing, usually from a stop and only giving it enough gas to accelerate normally (not trying to burn rubber or anything AT ALL) the car/power/boost will stutter... much like the equivalent of a person stuttering I suppose. So... if someone who were not used to driving my car were to accelerate from a red light, for example, they might feel the initial small amount of peddle pressure was insufficient and press it more only to then accelerate more than wanted because the boost/power was "catching up" to the initial gas peddle press. If that makes sense.

I know - I need a code reader. I really do.
Broke right now though.

Thanks for this thread. Glad John20 got it sorted out!

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Post by Juan62 »

Lambo, you may need to change your CBV (spring). IPD has an HD-kit with three type springs. Get it installed.
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Post by jblackburn »

^If you're not holding boost, that is one of two possible reasons, and a good improvement anyway. I've got one waiting to go in my car, but I haven't had time to get around to it.
Also, very much related if not the same problem, is; If I press the gas peddle to any specific position, arriving at that position quickly, and then hold it exactly there, I notice that the RPMs go up and over where they seem they should be - because then then they fall below where they should be, and then (if I remember correctly) they go back up and level off somewhere in the middle of the two. :?
Um...take a video maybe? Sounds like the torque converter in 2nd/3rd gear doing its job. It tries to put the engine in its torquey powerband (2500-a tad over 3500 RPM) until the transmission catches up.
'98 S70 T5
2016 Chevy Cruze Premier


A learning experience is one of those things that says, "You know that thing you just did? Don't do that."

mercuic: Long live the tractor motor!

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Post by Juan62 »

My newHD TCV and CBV from IPD has finally trained itself, or me being the trainee. Took it after reset and followed instructions. Finally got it up to 14psi and held 7-10 seconds. The furthest its ever been, using the new CBV spring (RED). One day, I may put the blue in. This does include IPD ECU upgrade (years ago, and custom dual exhaust). NO tires smoking yet, even at takeoff, and while the wastegate was set at two full turns. Dunno if thats good or bad. CAM checking/adjustment next I guess.
98 S70 T5-M Brick for life

dbm123
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Post by dbm123 »

jblackburn wrote:From a cold start, drive gingerly under 2000 rpm for 5 minutes. Half the boost level is 5 psi. I borrowed a boost gauge from a friend with an rx7 to help calibrate mine, but really keepin it under 3500 rpm at a bit less than half throttle seemed to do the trick for me.
I went through this learning routine with mine and my city gas mileage went from 21 mpg to 12 mpg. jblackburn recommended rebooting the ECU... which I did and my gas mileage went back to normal. Should I have gone through the "learning" sequences again after rebooting the ECU???
Current Volvos:
2004 C70 HPT (wife)
2002 S40 1.9T (daughter)
2001 V70 XC (daughter)
1999 V70 GLT (now dead)
1998 V70 GLT (son)
The other car: 2003 Saab 9-3 SE Convertible (mine)

dbm123
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Post by dbm123 »

Still interested in opinions about my question....
Current Volvos:
2004 C70 HPT (wife)
2002 S40 1.9T (daughter)
2001 V70 XC (daughter)
1999 V70 GLT (now dead)
1998 V70 GLT (son)
The other car: 2003 Saab 9-3 SE Convertible (mine)

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Post by LamboSE5 »

Juan62 wrote:Lambo, you may need to change your CBV (spring). IPD has an HD-kit with three type springs. Get it installed.
I plan on the new diaphragm and spring when I can, from vivaperformance (mitsubishi 'upgrade'). I can't do IPD, I live in Canada, and they have...freakin' rediculous shipping costs. I'll continue to say so until they change that :|
jblackburn wrote:^If you're not holding boost, that is one of two possible reasons, and a good improvement anyway. I've got one waiting to go in my car, but I haven't had time to get around to it.
Also, very much related if not the same problem, is; If I press the gas peddle to any specific position, arriving at that position quickly, and then hold it exactly there, I notice that the RPMs go up and over where they seem they should be - because then then they fall below where they should be, and then (if I remember correctly) they go back up and level off somewhere in the middle of the two. :?
Um...take a video maybe? Sounds like the torque converter in 2nd/3rd gear doing its job. It tries to put the engine in its torquey powerband (2500-a tad over 3500 RPM) until the transmission catches up.
I'll try n' do that if I get the chance soon :)

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