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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

j-dawg
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Re: 1996 855 T5 - Musings on Wastegate Adjustment

Post by j-dawg » Sun May 15, 2016 8:59 pm

I was curious about why ME7-managed engines need more caution. Interesting comment from ARD's Lucky on the subject:
http://forums.swedespeed.com/showthread ... ost1099929

Not sure I understand what he's getting at here - he explains what would happen if you adjusted the wastegate rod too loosely, ie, the computer would have to deliberately actuate the TCV to keep the wastegate closed, which is less desirable than just setting the actuator correctly. However, the real question is what happens if you set the rod too tightly, forcing the wastegate to stay shut above 4.5psi. Because boost pressure is used to actuate the wastegate, the computer would have no means of opening the wastegate until the wastegate setting was reached, no matter how much it wanted to. That's the more likely scenario for an owner adjusting his wastegate, and why that's worse in an ME7 car than a Mo 4.4 car isn't clear.

--- begin guesswork ---

It seems like the main point of Lucky's post is that the ECU in an ME7 car wants to supply a particular torque, which it does by controlling several parameters (fuel, spark, throttle, boost, etc), rather than react to throttle-induced airflow. By setting the wastegate actuator too high you deny it one of those parameters, and it will be unhappy.

By contrast, a Motronic ECU, as found in the older cars, is not looking to supply a particular torque. A Motronic 4.4 ECU on a turbo engine with a distributor has two jobs: regulate boost pressure, and supply the right amount of fuel for the air in the system. The driver is, like a caveman, regulating that air with his foot and a pull cable, so the computer has fewer control parameters and simpler goals to achieve. Being off by a bit is easier for the system to absorb.

--- end guesswork ---
1999 V70 T5 5-SPD | ~270k mi | burns more oil than gasoline

Sommerfeldt
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Re: 1996 855 T5 - Musings on Wastegate Adjustment

Post by Sommerfeldt » Mon May 16, 2016 3:22 am

j-dawg wrote:... like a caveman...
:lol: :lol: :lol:

FWIW, I think your guesswork is spot on. I pondered about that explanation from Lucky a while as well, and came to just about the same conclusion.

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

hausmeister
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Re: 1996 855 T5 - Musings on Wastegate Adjustment

Post by hausmeister » Wed May 18, 2016 6:04 am

Since I last filled up I also had less fuel consumption, about 11Ltr. I didn't expect that to be sure... more boost should mean more fuel I would think.
I'm not worried about the boost being too high. It seems perfectly safe and like I said, if anything the pressure builds more smoothly than before.

@Sommerfeldt: Do you have a manual transmission? Mine is automatic.
s70 '98 2L na manual Image || 850 T5-R '95 auto Image

Sommerfeldt
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Sommerfeldt

Re: 1996 855 T5 - Musings on Wastegate Adjustment

Post by Sommerfeldt » Wed May 18, 2016 9:01 am

hausmeister wrote:@Sommerfeldt: Do you have a manual transmission? Mine is automatic.
Mine's an automagic ;) as well. I love my auto, and I don't think I'd go back to manuals again.
Fuel consumption is down to 10.6 now, seems to have stabilized there with mixed city/highway driving - I'm sure it'd drop another couple of points if I was taking longer trips. :)

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

hausmeister
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Re: 1996 855 T5 - Musings on Wastegate Adjustment

Post by hausmeister » Thu May 19, 2016 6:59 am

I think for an "automagic" T5 that is a very good number.
(And I also like the automatic, well at least half of the time. It is perfect for cruising and for city driving, but on the country roads and highway I often wish I had more control. Paddle shifters would have been nice, but sadly the one or 2 guys that did that mod never made this commonly available.)

Maybe I will play with the setting some more when I have time.
s70 '98 2L na manual Image || 850 T5-R '95 auto Image

hausmeister
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Re: 1996 855 T5 - Musings on Wastegate Adjustment

Post by hausmeister » Sat May 21, 2016 10:28 am

Tried ~3.5 psi today, and the car seemed very happy. much better response, no issues. Then I tried 4psi, the ecu had to correct in the higher rpm range, but since it was able to correct it seems like this is still ok.
This definitely helps a lot with the turbo lag, feels way better. It is difficult to say with the automatic, but it seems safe so far. I'll drive a bit like that and keep an eye on my 2nd boost gauge.
(Keep in mind I have added an ipd BCS, just fyi)

I can only recommend you get a cheap blood pressure gauge (like http://www.amazon.de/Blutdruckmessgerät ... 004VCUNWS/ ) - this makes adjusting really easy. It reads in hgmm (at least mine does) which can be easily converted using an app or google. Just cut off the arm cuff and you are ready to go.
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Sommerfeldt
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Re: 1996 855 T5 - Musings on Wastegate Adjustment

Post by Sommerfeldt » Sat May 21, 2016 4:15 pm

That seems like a good idea - I've got a medical supply store right here in town, so I might stop by and get one of those.

Remember that if you set it too high, though, fuel economy is bound to go down, so you'll be back in the 11's before you know it. :lol:
It seems to me that the cluster boost gauge is pretty accurate, it's just a shame that there are no kind of measurements on it. I'm looking for a nice 2nd one now, which doesn't take a structural engineer to get a good install with. :)

I've tinkered with the adjustment a little - I'm still at 1,5 turns, but I tried setting it back to where it was, and immediately noticed that there was some play in the rod. Seems like in addition to the wrong setting, my WG has been bleeding off metered air, causing all kinds of shenanigans. To me, adjusting the WG actuator should be on the Stage 0 list, as well as a top thing to check if a turbo Volvo's running rich.

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

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Clemens
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Re: 1996 855 T5 - Musings on Wastegate Adjustment

Post by Clemens » Mon Aug 21, 2017 3:00 am

I´d imagine you get worse mileage under boost with these generation cars. What the turbo does is that it forces more air into the combustion chamber, thereby creating a need to inject more fuel. The more boost, the more fuel. Kinda like stomping on the pedal really hard on a carburetted engine.

Also, I am pretty sure that the fuel map enriches the mixture in higher rpm/boost levels to keep everything safe for the motor, thereby using more fuel than at lower rpms.

Another post these days suggested that the best fuel economy on T5s is at 3000 rpm.
Summer: 1996 855 R
Winter: 1994 855 T5M
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mecheng
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Re: 1996 855 T5 - Musings on Wastegate Adjustment

Post by mecheng » Tue Aug 22, 2017 11:16 am

800artfreed wrote:
Sun Aug 20, 2017 7:52 pm
I would like to add my 2 cents.
I have two '98 T5s. My V70 has always performed well but my S70 has always felt like it wouldn't "breath" or develop power in the same way as the V70. S70 got slightly better gas mileage but less power.

As an aside I would like to add my experience with the S70 dying on the highway recently when attempting WOT. After pulling the MAF connector the car ran well. I ordered I new MAF and installed it 2 days later. The car ran but not well. I just happened to notice that the rubber hose from the turbo output going to the inter-cooler was COMPLETELY disconnected. Reconnecting the hose allowed the metered air to be supplied to the engine and the ECU was able to run the engine correctly. BTW I did NOT have an engine code (check engine light) and the original MAF is probably still good. I cleaned it and am saving it for emergencies.

OK back to the wastegate. After reading articles on this site and making my own pressure gauge from a fuel pressure gauge/vacuum gauge I measured movement of the actuator with only 2-3 lbs of pressure! I applied 5 - 6 lbs of pressure and adjusted the link. This is a 200K car and the adjustment nut was very rusty. I strongly recommend using Deep Creep from SeaFoam company, spray liberally, wait, and hold the end of the link with vice grips while carefully loosening the 10mm nut. BTW the compression on all 5 cylinders is about 180 lbs psi with less than 10 lbs psi difference between cylinders.

Well the S70 is like a new car. Its FUN to drive! I really want to step on it. On the highway the car wants to go fast at speeds above 45mph, and above 2500 rpm the turbo kicks in and the car easily reaches 90+mph!

I do have a question about boost pressure and fuel consumption. Does higher boost lead to more fuel consumption? So far consumption seems higher with lower mpg. Perhaps I am just enjoying the power a little too much. I will reset the ECU by the battery method and allow it to relearn settings with the new MAF. I will let you know the results.
Yes thoeretically, but only when you are stepping on the gas hard, otherwise I didn't notice any change in gas mileage.
I did the same adjustment, completely changed the performance when in boost, otherwise it drives the same so that is why the gas mileage is the same. Before the adjustment, too much lag, after the adjustment it still lags but all the HPT T5 do.

How many turns did you do?
1998 Volvo S70 T5 - SE - 240km - Sold July 2018
1997 Volvo 850 GLT - 190km
Boost is my drug of choice

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