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1996 855 T5 - Musings on Wastegate Adjustment

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

Sommerfeldt
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1996 855 T5 - Musings on Wastegate Adjustment

Post by Sommerfeldt »

I know this has been discussed to death, but I thought I'd give this a nod as well...
I've been thinking about the WG adjustment for a good while, and alternated between do and do not. Mainly, because I think my wagon'o'rumble already is pretty quick, and because I don't have a lot of tools handy. Basics only - wrenches and screwdrivers are the mainstays of my toolbox. No gauges or meters or pumps and whatnot.

But, I read through most of the stuff about adjusting the WG actuator (including the ~250 post thread on Swedespeed or something) and watched all of Robert's videos on the subject, and got some good tips on where exactly my turbo gauge needle should be. It's never there... Considering that I don't have anything outrageous planned for the car, performance wise, I thought I'd give it a shot. Be sensible about it, and give it 1 turn. Maybe 2. Maybe.

First off, I found that how this thing is actually done is a little unclear. But I powered through it the other day, and took off my heatshield, loosened the little nut w/a 10 mm combination spanner, (things were a little rusty, but this was easy). Popped off the retainer on the actuator rod, and lifted it off. It seemed to have a little bit of play in it - I could pull it a mm or so before getting any resistance. After that, it was nice and tight.

I turned the adjusting head thing 1,5 turns, same direction as when loosening the nut, i.e. shortening the rod. Why not take the middle road, right? Popped everything back in place, heatshield and all, and the whole thing took about 10 minutes. Why I haven't tried it before, I'll never know.

I've been driving with it like this for a couple of days, and I gotta say. For 10 minutes "work", this is possibly nothing short of a miracle. If you haven't done this by now, do it right away. Boosts earlier, boosts more, boosts smooth as a newborn kitten. Or other simile according to your own preference.

The other thing I've noticed is an immediate improvement in mpg. Being mindful of the change I've made is probably the biggest thing contributing to it, I guess, but I see more power earlier, I don't have to put my foot down to get some oomph, and that makes a big difference. Getting on the highway is a breeze, and watching eyebrows go up as I leave shiny new whatnots in the rear view with nothing but a light tap on the gas is always a moodboost. Pun intended, I suppose.

So, if you haven't done this on your 850 or V70 or S70 or whatever, I recommend it heartily. Pop the heatshield off, loosen the nut, turn the adjustment head the same way 1,5 turns, and boost your little heart out.

- S
'96 855 T5, R bumper and spoiler, Koni Yellows & blue H&R springs all 'round.
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Re: 1996 855 T5 - Musings on Wastegate Adjustment

Post by Clemens »

Thanks for the motivation! Might have to give that a try
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Re: 1996 855 T5 - Musings on Wastegate Adjustment

Post by hausmeister »

You can use an old fashioned blood pressure gauge off amazon or ebay to set the wastegate. These are pretty cheap and work fine. Better than using guesswork.

On my engine the WG should be set to ~1.8ps1... i had set it to this for the last 2 years since I was working on getting everything working as intended.

Recently I decided to try and change the setting again to about just below 3psi.
The boost comes on much earlier, and it seems to hold a bit more power in higher rpm.
On the other hand, with the lower setting the boost would come on later, but when it did it was full force, sometimes spinning the wheels. It feels like this kick in mid range is now much less, but overall it feels more driveable.

Well, that is my experience. I'm hoping for better weather so I can install an exhaust and other upgrades I finally got.
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Re: 1996 855 T5 - Musings on Wastegate Adjustment

Post by Sommerfeldt »

Yeah, I guess it's better than guesswork. But, as long as it's not overboosting afterwards, and as long as one doesn't go overboard with the turns, I suppose it's fine. :) With 1.5 turns, I think most should be safe. Keeping an eye on the boost gauge is never a bad idea, though.

I agree with you on your observations. The early onset of boost does give a noticeable kick at start, and it seems to me that the curve is much smoother now - there's no sudden kick in mid range. It feels to me like the boost just builds more like it should, and holds better through shifts. Also, like I mentioned, I've been driving with this for just a few days, and my mpg is improving rapidly, from about the same as the T5-R in your sig (11.7 pr 100 km) to about 10.9 where it sits right now - looks like it's still dropping. Improving, that is. :)

- S
'96 855 T5, R bumper and spoiler, Koni Yellows & blue H&R springs all 'round.
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Re: 1996 855 T5 - Musings on Wastegate Adjustment

Post by gswede »

Sounds like you found the sweet spot. Spring in the OEM WG will wear over time and a little adjustment like this can be helpful.
Seeing as you don`t have gauges and what not, just keep track of how many turns you adjust.
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Re: 1996 855 T5 - Musings on Wastegate Adjustment

Post by rspi »

Be careful with more boost at lower RPM. A lot of these cars bend rods this way. This is the main problem with over sized turbos and manual boost controllers.
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Re: 1996 855 T5 - Musings on Wastegate Adjustment

Post by Clemens »

@rspi:
So then Volvo created that turbo lag on purpose by adjusting the wastegate moderately? I also read somewhere that in 1st gear the ecu cuts back performance on AT cars to save the tranny.
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Re: 1996 855 T5 - Musings on Wastegate Adjustment

Post by j-dawg »

Yes - the boost map keeps boost low at low engine speeds to avoid knock, which, as Robert pointed out, can to have cause you a very bad day. This is controlled by actuating the wastegate.

The factory map tends to be pretty conservative, but it's definitely something to consider. I think it's worth doing with a handheld vacuum pump and a gauge. You can choose how far past the factory spec you want to go, but I've always found the "turns" metric to be very vague, anchored as it is in the assumption that your wastegate has never been adjusted. Better to set the wastegate to a target pressure, I think, than an arbitrary number of turns. (I should note that I've never touched the wastegate on my car, so I am making pronouncements about things with which I have zero experience.)
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Re: 1996 855 T5 - Musings on Wastegate Adjustment

Post by abscate »

Just to add to thread, I've read this is a place to play on 1998 and earlier, while 1999 on shouldn't mess with the waste gate
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Re: 1996 855 T5 - Musings on Wastegate Adjustment

Post by Sommerfeldt »

abscate is right - 1999 onwards are much more sensitive to adjustment of the wastegate. '95 - '98 has a lot more room to play with, and in reading through all of the forum posts and other information I could find on adjusting it, it seems that 3 turns are the upper limit with the generation I'm in with the '96. My 1,5 turns seems to be absolutely the sweet spot, like gswede said. That will certainly vary from wastegate actuator to wastegate actuator, but I'm pretty certain that I'm well within tolerances no matter what.

Robert mentions the main reason I've been hesitant to try this little tinker. The WG and actuator are there for good reasons, and they're set the way they are for good reasons as well. That said, there's no need to baby these engines. The auto tranny expects up to 300 hp. There are people around building these engines to 600+ hp (some much higher, but the number of stock parts dwindles rapidly). I don't have an MBC or anything drastic like that, and even if I did, I'm certainly not overboosting with this adjustment. The boost climbs smoothly with RPM and load, and even at WOT it never goes past ~11 psi - that's clear, even with just the cluster gauge to go by.

Overdoing this adjustment is certainly a very bad idea - that much I've gleaned from the hundreds of forum posts and pages of info I went through. But, as our cars get older, they need adjustments, and I'm pretty sure that this is one of the items that are overlooked which actually should get more attention than it does. It should probably be done with pressurized air and all that, I'll concede to that. Eyeballing it may not be safe in all instances.

On a lighter note, my fuel efficiency is continuing to improve, despite a lot of spirited driving following the WG adjustment. I'm down to 10.6 l pr 100 km, and that number's still improving. That's 22 mpg and climbing. Just sayin'. ;)

- S
'96 855 T5, R bumper and spoiler, Koni Yellows & blue H&R springs all 'round.
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