ASV as engine brake???

As part of my daily commute i drive up and down a really steep and curvy road. I can smell my brakes burning on the downhill side. If i wire up a vacuum solenoid to my ASV to close it while i'm coming down the hill would that make the ECU go crazy and throw codes or go into limp mode??? Or on the other side of things can i do the same with the turbo actuator to make it into an exhaust brake like the 6.7 liter cummins does???
I have missed my pete 379 and its C15 cat for jake brake....like dropping an anchor overboard....
But i digress...can i use whats on my ALH engine to give it some kind of engine braking???

Closing asv will not noticeably increase engine braking. Not at all like a jake or turbo vane choke like the 6.7.

So even a closed ASV or closed out VNT vanes wouldnt give me any braking effect??
Ive driven big trucks that only have exhaust brakes....nothing like a jake brake but at least it was something helping me slow down...

I have fo admit when i first got the car i found myself looking for the paddle on the shifter to go to the next range of gears...i

Closing of air intake to a diesel (what the asv does) does not really increase engine braking much. I was playing around with my asv and hooked up the solenoid to cycle it on and off. I could hardly tell the difference. Intake stroke takes work against the 14psia vacuum, comp stroke very little work, exp stroke very little work recovered, exhaust stroke very little work there too. Net is like..very little.

Jake cocks open valves, which vents partial compression. So energy put into compression is not returned when piston goes down. Very effective. Same with an exhaust brake, it is choking the outlet of the pump (what the engine is) and pressure rises and is thottled through the valve. Exhaust stroke then must force out air against the throttle. Lots of work there.

galaxyclass said:

I can smell my brakes burning on the downhill side.

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Try taking it slower.

So my best bet is to use the vanes on the vnt to choke up the exhaust.... That seems to be what i'm hearing. My question is if i do so will it make the ECU go crazy...
This ALH has to be one of the most fussy diesels i have worked with....

So my best bet is to use the vanes on the vnt to choke up the exhaust.... That seems to be what i'm hearing.

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No! What you're hearing is very directly that the ASV is not a viable means for engine braking, and (admittedly, a bit less directly) that manipulating the turbine vanes is also not a viable means for engine braking. Engine brakes operate differently from what the variable vane geometry does in a turbo. If you manipulate the turbo actuator to apply vacuum beyond what the ECU does for operational boost, it won't cause any appreciable engine braking. It will simply speed the turbo and make boost at a time when the ECU isn't calling for it. At that point, I agree with what you surmise- the ECU will probably detect the unrequested boost and set a code, perhaps limp mode etc.

Back to the main point- I haven't heard of an engine brake for the ALH engine. Maybe one exists, but I haven't heard of it. If you have to drive steep hills and overheated brakes are a problem, only things I can think of are reducing speed, take a close look at optimizing your use of the brakes. I'm going to guess there's probably not an alternate, less hilly... route.

I think the ALH engine brakes very well, personally. Use your transmission. Downshift a gear. Maybe two. I go up and down steep grades quite frequently here and I've never had an issue going down a gear or two to maintain adequate speed. Even if you do have to use the brakes when you've gone down a gear, it will be much less than if you just left it in the normal gear for the speed.

Also, instead of staying on the brakes the whole time, constantly putting heat to them, give them a good amount of pressure to slow down more than needed, then let it coast and pick up speed again. Doing this will allow the brakes some time to cool back down before you need to use them again.

A little common-sense driving goes a long way and totally negates the need to do any silly engine modifications. Trucks need it because they are carrying massive loads that just continue to push them down a grade. Your TDI does not.

Ok. I guess I'm still stuck on my heavy diesel mindset. Even with the jakes on my truck i still use the stab and release thing on my brakes. It just seems wrong to me to downshift a gear or two and not slow down much. I'll just forget my jetta is maybe 3000lbs not 80,000 lbs....

galaxyclass said:

Ok. I guess I'm still stuck on my heavy diesel mindset.

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Based on your posts above, and with all due respect, I would agree with you.

The trucks you are used to driving and the car you now drive burn the same fuel... in very very different engines that are roughly based on a design Rudolph Diesel came up in the late 1800's.

That is about all they have in common.

Nothing wrong with downshifting and letting it rev to increase engine braking. Even if engine is noisy, it does not hurt it. When I'm in the mountains, I'll select a gear that gives me 3500 turns or less. Barely need brakes then unless going down a cliff.

i'll throw in my 2 cents....

Your assuming engine braking will increase due to pumping losses increasing with ASV closed, but not so much. Think about how a 4 stroke engine works.

Closing the ASV valve while costing will not give you engine braking because... you will be pulling in NO air (or virtually no air) into the cylinders.

Intake stroke...... So during intake stroke you will make a vacuum (with slight additional pumping losses with the ASV closed).

Compression stroke .....On compression stroke the vacuum that the intake stroke just made will pull the piston back up.

Power stroke will probably make a vacuum if injection quantity is zero, which it is sometimes when coasting, with additional pumping losses, but if the injected quantity goes up at all the combustion will negate any pumping losses because the combustion will fill the vacuum. EDIT: AndyBees pointed out that there would be no combustion even if fuel was injected as there would be virtually no air to compress. Excellent point.

Exhaust stroke will be no different than normal other than it might vent some of the vacuum from the power stroke if the injection quantity is zero.

Pumping loss during the compression stroke would be the main energy loss that would give you engine braking, and with the ASV closed you mostly loosing this due to the vacuum pulling the piston up. So with the ASV valve closed you gain some pumping loss on intake and possibly on power stroke, but since your loosing the energy loss from the compression stroke your probably losing more than your gaining. (your loosing more pumping losses than your gaining... does that even make sense?)

And the reason I know this is...I've had a couple customers vehicles that were towed in for no start where the ASV valve was stuck closed, and when you first try to start them they crank really fast like no compression because of what I described in the previous paragraphs. Have to watch yourself when you get one of these cuz your knee jerk reaction is to think it has a broken belt with no compression.

Agree 100% ^^^^ that's exactly how my Jetta acted when the ASV got stuck due to a foreign object getting into the lever. The engine would spin over fast and with ease without starting.

I might add, if there was injection during a compression stroke (ASV closed), there would be no combustion due to low heat (virtually no air to concentrate heat).

apologies to OP, we've sort of taken this tangent and run with it... (but I'm going to continue just a bit...)

I'd say the pumping losses are a net decrease with the ASV closed. (I think CoolAir is saying the same thing...) In fact, that's why the ASV was implemented in the first place- to eliminate the annoying shudder which is caused by the compression strokes as the engine coasts to a stop. Again viewed in the condition of engine braking, your foot would likely be off the accelerator, so no fuel would be injected. That pumping losses are LESS with the ASV closed is corraborated (sp?) by the fact that the engine is observed to crank faster when the engine has a fault that keeps the ASV closed; the same battery, and the same starter motor... is able to crank the engine faster.

Why do a lot of TDI owners want to make our cars like trucks?

They want huge skid plates, AWD, huge tow loads, engine brakes, smoke stacks...bla bla bla.

Sweet jesus its a car.

NB_TDi said:

Why do a lot of TDI owners want to make our cars like trucks?

They want huge skid plates, AWD, huge tow loads, engine brakes, smoke stacks...bla bla bla.

Sweet jesus its a car.

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Yes, but it's his car and he relates to his experiences
This is what most enthusiasts do

My 3 cents: Maybe he could add a parachute "brake"
Along with a loud recording of a jake brake in action !
Talk about a custom mod !!

Personally, I would just make sure my brakes were good quality and maintained

AndyBees said:

I might add, if there was injection during a compression stroke (ASV closed), there would be no combustion due to low heat (virtually no air to concentrate heat).

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Excellent point!

Something is wrong with your car if its standard issue brakes are unable to keep the car under control. I've towed other cars behind my ALH through the mountains and I never once had any cause for concern. It stopped fine, and was able to allow me to maintain perfect control. I just used a lower gear to help.

I'll throw it out there just for the sake of discussion (since it came up already)... closing the VNT on some turbocharges DOES create a significant engine braking effect (several pickup truck manufacturers incorporate this as a feature in tow/haul mode). However, I don't think that the TDI's stock turbo creates as much of a restriction in the closed mode as some other turbos do, thus reducing the engine braking effect even with the vanes in their completely closed position.

As others have mentioned, downshift to a lower gear to create more of a braking effect, start the hill at a slower speed, don't ride the brakes all the way down so they don't build up as much heat, etc.

I have also noticed very weak engine braking on 1.9TDI PD so I tried to figure out what ECU is doing with ASV, EGR and VNT while engine braking.
On idle EGR is at 45% duty cycle(MAF reading ~230mg/str instead of ~470mg/str when EGR turned off), VNT at 85% duty cycle. ASV is electrically controlled on EDC16 so there is no way to see its position. I heard that it is closing a little bit during easy driving to help exhaust gasses enter but I have not seen any evidence of that..
At full throttle EGR is at ~96% duty cycle(fully closed), VNT at ~ 40% duty cycle on 3000+ rpm.(so the vanes are opening with lower VNT duty cycle to control boost in intake which is approx. 2bar, 29psi)
Now with engine braking:
first situation:
-2500rpm, pedal 0%, EGR 96% duty cycle, MAF ~500mg/str, MAP 1,24bar(18psi), VNT 70% dc, speed 60mph
second:
-2400rpm, pedal 0%, EGR 96%, MAF ~500mg/str, MAP 18psi, VNT 69%, speed ~58mph
So it's evident that EGR is closed while engine braking, so as ASV fully opened probably? VNT vanes are also pretty much at closed position, maybe to improve engine braking? What are your thoughts on this?
EDIT: Forgot to ask.. 18psi of boost while engine braking.. how's that?

Skylake said:

I have also noticed very weak engine braking on 1.9TDI PD so I tried to figure out what ECU is doing with ASV, EGR and VNT while engine braking.
On idle EGR is at 45% duty cycle(MAF reading ~230mg/str instead of ~470mg/str when EGR turned off), VNT at 85% duty cycle. ASV is electrically controlled on EDC16 so there is no way to see its position. I heard that it is closing a little bit during easy driving to help exhaust gasses enter but I have not seen any evidence of that..
At full throttle EGR is at ~96% duty cycle(fully closed), VNT at ~ 40% duty cycle on 3000+ rpm.(so the vanes are opening with lower VNT duty cycle to control boost in intake which is approx. 2bar, 29psi)
Now with engine braking:
first situation:
-2500rpm, pedal 0%, EGR 96% duty cycle, MAF ~500mg/str, MAP 1,24bar(18psi), VNT 70% dc, speed 60mph
second:
-2400rpm, pedal 0%, EGR 96%, MAF ~500mg/str, MAP 18psi, VNT 69%, speed ~58mph
So it's evident that EGR is closed while engine braking, so as ASV fully opened probably? VNT vanes are also pretty much at closed position, maybe to improve engine braking? What are your thoughts on this?
EDIT: Forgot to ask.. 18psi of boost while engine braking.. how's that?

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You have to subtract ambient from MAP in order to get boost, or gauge pressure. So if you were at sea level, you'd subtract about 14.5 PSI from your reported 18, leaving you with 3.5 PSI of boost pressure in that situation.

On my 6.0 PowerStroke, I had a tune that would do engine braking with boost pressure. It would crank the VGT to the max boost position at 0% throttle, creating a lot of engine braking. At 2500 RPM and 0% throttle, it would churn out 15 PSI of boost pressure - great for towing down mountains.

VeeDubTDI said:

You have to subtract ambient from MAP in order to get boost, or gauge pressure. So if you were at sea level, you'd subtract about 14.5 PSI from your reported 18, leaving you with 3.5 PSI of boost pressure in that situation.
On my 6.0 PowerStroke, I had a tune that would do engine braking with boost pressure. It would crank the VGT to the max boost position at 0% throttle, creating a lot of engine braking. At 2500 RPM and 0% throttle, it would churn out 15 PSI of boost pressure - great for towing down mountains.

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I understand that(ambient pressure), but still, 3.5 PSI at ~2000rpm with no combustion? I thought that ASV is maybe (almost) closed while engine braking so it "chokes" intake so that's the reason why MAP sensor (in front of ASV) reads that 3.5 PSI of boost..
I'm not sure but I think that boost of 3.5 PSI drops to ~ 0 PSI as soon as I press pedal slightly.. but I'm not sure, gonna check it next time.

Speaking of Powerstroke.. 15 PSI on engine braking? WOW
What is "normal" boost pressure for that Powerstroke at full throttle?

Normal boost under load is 20 psi stock, 20 psi on the tow tune, and 35 psi on the street tune.

Something not yet brought up here....the clutch specificaly the dual mass flywheel and also the disk, especially if it is sprung, wears significantly more when loaded in reverse while downshifting.

My advice would be to invest your time and money in upgrading your brakes instead of replacing your clutch sooner.

For the last 6 months, I've been having a few electrical problems with my ALH Vanagon. ........

So, without all the details, occasionally, when I let up on the accelerator, the ASV will close. The Turbo gauge, which also shows vacuum, will drop to almost 30 inches vacuum and a very noticeable noise comes from the engine ...... there's very little, if any additional braking. The instant I apply the accelerator, the ASV opens and engine function goes back to normal.

This strange issue takes place very rarely!

VeeDubTDI said:

Normal boost under load is 20 psi stock, 20 psi on the tow tune, and 35 psi on the street tune.

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Does that Powerstroke 6.0l have ASV maybe?
I found this thread and interesting thing is that if you press pedal even slightly boost drops to ~0.5 PSI. What can cause this drop?
If not EGR opening then it's ASV closing or VNT vanes opening, right? Lets say I close EGR and watch at VNT vanes duty cycle, if they stays at the same position(or closes even more) then it's obvious that ASV is closing(idk how much) at engine braking?
Because it sounds very weird that engine at ~2000rpm can't suck in all the air that turbo boosts without any combustion in cylinders.

Here's an update:
So I closed EGR mechanically(disconnected vacuum hose and clogged it) and also disconnected ASV.

At ~ 61km/h, pedal 0%, engine speed ~2000rpm, VNT at 70%(as usual) intake boost is ~ 0,24bar, ~3-4PSI.

I noticed something strange.. while engine braking I can hear hissing sound under the bonnet. As soon as I press pedal even slightly it disappears.

Not sure is it hissing with EGR and ASV connected, I will check it next time.