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99 T5 - questions about boost control: boost maps, why the adjuster 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
1997 - 2000 S70, S70 AWD
1997 - 2000 V70, V70 AWD
1997 - 2000 V70-XC
1997 - 2004 C70

j-dawg
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Re: 99 T5 - questions about boost control: boost maps, why the adjuster

Post by j-dawg » Tue Sep 06, 2016 10:10 pm

tryingbe wrote: Try it, see what happens.

I predict your boost response will be super slow, you might get 5psi by 4000rpm while WOT.
I'm not asking because I want to do it. My car runs fine and boosts well. I want to understand how the system was designed, to satisfy my curiosity. It's not an intuitive setup.
sleddriver wrote:On years up to 98, there is no "boost gauge" per sae. Instead it's a calculated value. On 99+, there IS a boost gauge to directly monitor the amount of boost.

My understanding of mechanical WGs is that pressure alone will open them if sufficient. Mine was so loose, I'm surprised I had any boost at all. The TCV allows boost to be shunted around the turbo if necessary or not, if not. Depends upon the ECU based upon all the sensor readings & its programming.
Separately from the manifold pressure sensor, I installed an actual boost gauge in my car, because I'm a child and the motion of the needle amuses me.

Good call on the Fast Friday pages:
http://www.matthewsvolvosite.com/forums ... hp?t=53189

What I learned from that page: the TCV is effectively a fail-open valve to the wastegate actuator, such that, when it is unpowered, the wastegate actuator is connected to the intake manifold. So the ECU doesn't open the TCV to actuate the wastegate and lower boost, as I'd been assuming. It closes the TCV to prevent the wastegate from opening when it wants to build boost. In case of a TCV failure, the engine is protected from overboost by a wastegate that opens at 4.4psi.

That same principle makes it important to have a nicely-balanced wastegate set point. Too high and you risk engine damage if the TCV fails. Too low and you will keep accidentally opening the wastegate at low boost, before the ECU starts closing the TCV. 4.4psi is above the 1-2psi where the engine starts toggling the TCV, but below the kind of pressures that might damage an engine at low RPM.

Not explained in the FF article is why the ECU doesn't start actuating the TCV until 1-2psi. My guess would be this is down to the specifics of the mechanical system. Perhaps Volvo found less accidental actuation the wastegate, and thus better low-speed boost buildup, when the actuator was set with a higher preload.

Mystery solved! Thanks MVS! I can sleep now.
1999 V70 T5 5-SPD | ~270k mi | burns more oil than gasoline

j-dawg
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Re: 99 T5 - questions about boost control: boost maps, why the adjuster

Post by j-dawg » Tue Sep 06, 2016 10:14 pm

Ah! This is it! This is the answer. I was having so much fun on the compressor side of the turbo that I completely forgot the turbine. Mystery really solved this time!
1999 V70 T5 5-SPD | ~270k mi | burns more oil than gasoline

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RigsPGT
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Re: 99 T5 - questions about boost control: boost maps, why the adjuster

Post by RigsPGT » Tue Sep 06, 2016 10:31 pm

sleddriver wrote:On years up to 98, there is no "boost gauge" per sae. Instead it's a calculated value. On 99+, there IS a boost gauge to directly monitor the amount of boost.
There's no actual boost gauge in the S70s, 850s did have one with a sweep area and not with numbers! I have an aftermarket one tied in the vacuum lines to monitor the turbo as when I purchased my T5, it came with a BSR sticker, a manual boost controller (99s and ME7 say no no) and a 319whp and 345wtq dyno tune in the glove box but my butt dyno confirmed it. The gauge showed me I had no tune besides stock tune but I always thought the T5s boost 10.5psi and not 12psi.
Anyway, I don't know much how our cars control boost as I'm used with wastegate actuator control, manual or electronic boost controllers and external wastegates.
99 S70 T5, The Red Devil
Ported 19T and R manifold, 3" DP with Magnaflow race cat, 2.5" cat back, Precision FMIC, Rigs intake pipe, H&Rs, Bilsteins, 302's with Akebonos, Jewels, HIDs, egg crate grille, transmission cooler.

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sleddriver
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Re: 99 T5 - questions about boost control: boost maps, why the adjuster

Post by sleddriver » Tue Sep 06, 2016 11:56 pm

Thought I'd proof'd my post but still a momentary lapse of reason snuck in......

Should have stated that on years up to 98, there is no boost pressure sensor (not gauge), that directly reads boost pressure. On 99+ cars, there is a boost pressure sensor.

I typed "gauge" when I meant "sensor"......my apologies!
1998 V70 T5 226,808 miles. Original Owner.
M1 10W-30 HM

tryingbe
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Re: 99 T5 - questions about boost control: boost maps, why the adjuster

Post by tryingbe » Wed Sep 07, 2016 2:24 am

RigsPGT wrote:a 319whp and 345wtq dyno tune in the glove box but my butt dyno confirmed it.
Nice numbers, any chance I can get you to scan and share it?
85 GLH, 367 whp
00 Insight, 72 mpg

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RigsPGT
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Re: 99 T5 - questions about boost control: boost maps, why the adjuster

Post by RigsPGT » Wed Sep 07, 2016 8:50 pm

tryingbe wrote:
RigsPGT wrote:a 319whp and 345wtq dyno tune in the glove box but my butt dyno confirmed it.
Nice numbers, any chance I can get you to scan and share it?
I can share it but the car is not a 300hp and that is why I was digging for answers and installing a boost gauge. Basically I bought the car from a guy who bought it off a bank and he basically gave up trying to fix it(ETM+MAF problem)
Car had a muffler delete, MBC, BSR badge and a dyno sheet. No way this car would have made those numbers even with a tune but anyway, here's what i found in the glove box.
btw, sorry about the 345wtq, it got stock in my head ever since i got the car a year ago.
You do not have the required permissions to view the files attached to this post.
99 S70 T5, The Red Devil
Ported 19T and R manifold, 3" DP with Magnaflow race cat, 2.5" cat back, Precision FMIC, Rigs intake pipe, H&Rs, Bilsteins, 302's with Akebonos, Jewels, HIDs, egg crate grille, transmission cooler.

tryingbe
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Re: 99 T5 - questions about boost control: boost maps, why the adjuster

Post by tryingbe » Wed Sep 07, 2016 9:25 pm

That's strange! Mystery dyno sheet!
85 GLH, 367 whp
00 Insight, 72 mpg

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RigsPGT
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Re: 99 T5 - questions about boost control: boost maps, why the adjuster

Post by RigsPGT » Wed Sep 07, 2016 11:29 pm

It is and when I went to BSR's page, their Stage 3 for our cars put out 320hp (no idea if wheel or crank) but I'm thinking at some point the previous owner who had it, probably had a tune in it and brought it back to stock later on via softloader. Why one would go buy a BSR badge, install an MBC (again 99, pointless) and have a fake dyno sheet in the glove box, unless he was living in a Fast and Furious dream and tried to tell his buddies he's fast.
Either way if I can squeeze 319whp with my ported R manifold and ported 18T, 3"dp, 2.5" exhaust, front mount intercooler, I think I'll be happy :)
Sorry to the thread opener as we're drifting away from the original question!
99 S70 T5, The Red Devil
Ported 19T and R manifold, 3" DP with Magnaflow race cat, 2.5" cat back, Precision FMIC, Rigs intake pipe, H&Rs, Bilsteins, 302's with Akebonos, Jewels, HIDs, egg crate grille, transmission cooler.

Yarddogperformance
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Re: 99 T5 - questions about boost control: boost maps, why the adjuster

Post by Yarddogperformance » Wed Sep 26, 2018 7:47 am

Mbc not pointless, however at 8 psi my car runs fine, at 10 psi it makes more power for a sec. Than has a fuel supply issue with new pumps and filter. So, yeah it made power, once, but ill bet that engine is now part of a honda as it probly broke a sleeve,

I think we need flow, not pressure
Fuel and air
Im going gtx 30 76r but only stock pressure, this should increase no boost power, as well as boosted power.

Ditch the manual bc, i use mine to shut the bov off to make the turbo flutter on cruise night. Thats about all they are good for as far as we fit the crowd.

Carry on your plans, stay under 13psi, and if your over 8 install an afr guage, downtune till your at 11:1 afr at the leanest and you should be ok,
pressure dont =power
Valume and waight of fuel consumed make power. Go for flow, than go for broke

Yarddogperformance
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Re: 99 T5 - questions about boost control: boost maps, why the adjuster

Post by Yarddogperformance » Wed Sep 26, 2018 7:52 am

Oh yeah, tcv, is constant flow, when the pcm says more it opens and bypasses the gate, than pulses shut at the desired pressure, usually 7-9 psi on my car depending on that lil snowflake next to the up arrow

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