Identifying a Worn Out Wastegate Actuator
Discussion
If the wastegate actuator isn't working (i.e moving as it should, pushing the connecting rod to the wastegate and opening the wastegate to bleed off boost) then your car would be boosting up like buggery, going very fast indeed with probably lots of engine pinking, and finally melting down / blowing up!
The actuator's job is to bleed off boost as it builds, not to 'help' boost. It's a valve that is controlled by an electronic solenoid that allows engine vacuum into the unit to make it open up, and in turn open the turbo's wastegate to bleed off excessive boost, and hence not allow massive boost pressure to build up and destroy the engine.
If you are experiencing low / no boost, it could be that the wastegate or wastegate actuator are stuck in the 'open' positon. Easy to check.
Or it could be a leaking turbo inlet pipe, intercooler, or the turbo itself may be toast.
Can you give me a better explaination of what's happening?
The actuator's job is to bleed off boost as it builds, not to 'help' boost. It's a valve that is controlled by an electronic solenoid that allows engine vacuum into the unit to make it open up, and in turn open the turbo's wastegate to bleed off excessive boost, and hence not allow massive boost pressure to build up and destroy the engine.
If you are experiencing low / no boost, it could be that the wastegate or wastegate actuator are stuck in the 'open' positon. Easy to check.
Or it could be a leaking turbo inlet pipe, intercooler, or the turbo itself may be toast.
Can you give me a better explaination of what's happening?
Ray Luxury-Yacht said:
If the wastegate actuator isn't working (i.e moving as it should, pushing the connecting rod to the wastegate and opening the wastegate to bleed off boost) then your car would be boosting up like buggery, going very fast indeed with probably lots of engine pinking, and finally melting down / blowing up!
The actuator's job is to bleed off boost as it builds, not to 'help' boost. It's a valve that is controlled by an electronic solenoid that allows engine vacuum into the unit to make it open up, and in turn open the turbo's wastegate to bleed off excessive boost, and hence not allow massive boost pressure to build up and destroy the engine.
If you are experiencing low / no boost, it could be that the wastegate or wastegate actuator are stuck in the 'open' positon. Easy to check.
Or it could be a leaking turbo inlet pipe, intercooler, or the turbo itself may be toast.
Can you give me a better explaination of what's happening?
Your description of how they work is right, Mr. Yacht, but I'm not sure that this is how they "fail". When we replaced some actuators on the missus 20V 1.8T engine a while back, the symptoms were partly as you described, but not quite so scary:The actuator's job is to bleed off boost as it builds, not to 'help' boost. It's a valve that is controlled by an electronic solenoid that allows engine vacuum into the unit to make it open up, and in turn open the turbo's wastegate to bleed off excessive boost, and hence not allow massive boost pressure to build up and destroy the engine.
If you are experiencing low / no boost, it could be that the wastegate or wastegate actuator are stuck in the 'open' positon. Easy to check.
Or it could be a leaking turbo inlet pipe, intercooler, or the turbo itself may be toast.
Can you give me a better explaination of what's happening?
HUGE lump of initial boost, slight compressor-surge type noise then nothing, NA 1.8 time.
This was the wastegate actuator failing "safe", and dumping boost pressure as soon as it read anything. A conversation with the specialist who fixed the turbo for us yielded that this is due to their mechanical design: they can't fail "closed" per se and are designed to fail in such a way as to drop the engine out of boost as soon as possible. This way they don't cause the turbo to cook. I'm a little hazy on exactly how all this is achieved, but as regards symptoms of wastegate actuator failure, there they are on a 1.8T VW/AUDI engine.
fozzymandeus said:
Ray Luxury-Yacht said:
If the wastegate actuator isn't working (i.e moving as it should, pushing the connecting rod to the wastegate and opening the wastegate to bleed off boost) then your car would be boosting up like buggery, going very fast indeed with probably lots of engine pinking, and finally melting down / blowing up!
The actuator's job is to bleed off boost as it builds, not to 'help' boost. It's a valve that is controlled by an electronic solenoid that allows engine vacuum into the unit to make it open up, and in turn open the turbo's wastegate to bleed off excessive boost, and hence not allow massive boost pressure to build up and destroy the engine.
If you are experiencing low / no boost, it could be that the wastegate or wastegate actuator are stuck in the 'open' positon. Easy to check.
Or it could be a leaking turbo inlet pipe, intercooler, or the turbo itself may be toast.
Can you give me a better explaination of what's happening?
Your description of how they work is right, Mr. Yacht, but I'm not sure that this is how they "fail". When we replaced some actuators on the missus 20V 1.8T engine a while back, the symptoms were partly as you described, but not quite so scary:The actuator's job is to bleed off boost as it builds, not to 'help' boost. It's a valve that is controlled by an electronic solenoid that allows engine vacuum into the unit to make it open up, and in turn open the turbo's wastegate to bleed off excessive boost, and hence not allow massive boost pressure to build up and destroy the engine.
If you are experiencing low / no boost, it could be that the wastegate or wastegate actuator are stuck in the 'open' positon. Easy to check.
Or it could be a leaking turbo inlet pipe, intercooler, or the turbo itself may be toast.
Can you give me a better explaination of what's happening?
HUGE lump of initial boost, slight compressor-surge type noise then nothing, NA 1.8 time.
This was the wastegate actuator failing "safe", and dumping boost pressure as soon as it read anything. A conversation with the specialist who fixed the turbo for us yielded that this is due to their mechanical design: they can't fail "closed" per se and are designed to fail in such a way as to drop the engine out of boost as soon as possible. This way they don't cause the turbo to cook. I'm a little hazy on exactly how all this is achieved, but as regards symptoms of wastegate actuator failure, there they are on a 1.8T VW/AUDI engine.
A round metal device, with a rubber diaphragm inside. On one side of the diaphragm is an outlet with a connection - this connection has a rubber pipe leading from it to an electronically controlled solenoid valve - which is in turn plumbed to the engine vaccum / inlet manifold.
Also within the diaphragm side of the actuator is a very strong metal spring - which holds the diaphragm mechanism to one side of the actuator.
The other side of the diaphragm has a metal rod fixed to it, which pokes out of the opposite side of the actuator to the inlet pipe described earlier. Then this rod is connected to another rod which goes to the turbo's wastegate.
The spring inside the actuator, in it's resting state, is pushing the diaphragm as far as it can go, which in turn is pushing the connecting rod as far as it can go, which in turn is pushing the wastegate itself on the turbo closed.
The only thing that can open the wastegate and hence bleed off excessive boost, is the engine vacuum being introduced to the inlet side of the actuator, sucking the diaphragm towards it, overcoming the pressure of the internal spring, and hence pulling the connecting rod and opening the wastegate.
Hence, on the cars I've had at least - the actuator's default position is to keep the wastegate closed - so the opposite of the 'fail safe' you've mentioned.
But it may well be that things have changed or are different on other cars - as I said, this is on cars I've owned, so I'm no expert!
The return spring on the actuator arm can soften over time so you never develop full boost (the wastegate is always bleeding air from the turbo), there should be an amount of pre-load on the actuator spring. You can normally tighten this up by removing the clip holding the actuator arm to the wastegate, releasing the lock nut and and turning (assuming it is a threaded rod as most are).
Ray Luxury-Yacht said:
Ah ok - well I'm not an 'expert' by any means - but on all the turbo cars I've had, the actuator device is thus:
A round metal device, with a rubber diaphragm inside. On one side of the diaphragm is an outlet with a connection - this connection has a rubber pipe leading from it to an electronically controlled solenoid valve - which is in turn plumbed to the engine vaccum / inlet manifold.
Also within the diaphragm side of the actuator is a very strong metal spring - which holds the diaphragm mechanism to one side of the actuator.
The other side of the diaphragm has a metal rod fixed to it, which pokes out of the opposite side of the actuator to the inlet pipe described earlier. Then this rod is connected to another rod which goes to the turbo's wastegate.
The spring inside the actuator, in it's resting state, is pushing the diaphragm as far as it can go, which in turn is pushing the connecting rod as far as it can go, which in turn is pushing the wastegate itself on the turbo closed.
The only thing that can open the wastegate and hence bleed off excessive boost, is the engine vacuum being introduced to the inlet side of the actuator, sucking the diaphragm towards it, overcoming the pressure of the internal spring, and hence pulling the connecting rod and opening the wastegate.
Hence, on the cars I've had at least - the actuator's default position is to keep the wastegate closed - so the opposite of the 'fail safe' you've mentioned.
But it may well be that things have changed or are different on other cars - as I said, this is on cars I've owned, so I'm no expert!
I agree: your description makes total sense. I'm relying on the comments made by a mechanic who diagnosed and fixed a boost fault on our car, rather than my own understanding... so I don't really know what design feature would allow it to failsafe! A round metal device, with a rubber diaphragm inside. On one side of the diaphragm is an outlet with a connection - this connection has a rubber pipe leading from it to an electronically controlled solenoid valve - which is in turn plumbed to the engine vaccum / inlet manifold.
Also within the diaphragm side of the actuator is a very strong metal spring - which holds the diaphragm mechanism to one side of the actuator.
The other side of the diaphragm has a metal rod fixed to it, which pokes out of the opposite side of the actuator to the inlet pipe described earlier. Then this rod is connected to another rod which goes to the turbo's wastegate.
The spring inside the actuator, in it's resting state, is pushing the diaphragm as far as it can go, which in turn is pushing the connecting rod as far as it can go, which in turn is pushing the wastegate itself on the turbo closed.
The only thing that can open the wastegate and hence bleed off excessive boost, is the engine vacuum being introduced to the inlet side of the actuator, sucking the diaphragm towards it, overcoming the pressure of the internal spring, and hence pulling the connecting rod and opening the wastegate.
Hence, on the cars I've had at least - the actuator's default position is to keep the wastegate closed - so the opposite of the 'fail safe' you've mentioned.
But it may well be that things have changed or are different on other cars - as I said, this is on cars I've owned, so I'm no expert!
For all the ECUs and sensors, sucking of teeth because of blah blah on modern cars... There will still be mechanical bits that can "let the side down" but can be adjusted and the effects of said adjustments checked.
Here's hoping it's a simple job like the wastegate actuator that is letting you down
. Sounds like you have a good garage who know their stuff - and aren't after easy money from you for 'further diagnosis' .
Here's hoping it's a simple job like the wastegate actuator that is letting you down
. Sounds like you have a good garage who know their stuff - and aren't after easy money from you for 'further diagnosis' .wolfsburggolf said:
This sounds very much like what my car is doing. It boosts lower down the rev range, then dies higher up all the way to the redline. I'm getting closer to being pretty sure it's the wastegate actuator?
fozzy, did you find that your 1.8T's power curve changed as the actuator wore out?
Yes it did. It became less linear. We have the 180bhp application and it's pretty linear, but when the actuator was failing it became more "Lag-BOOST" in character before finally popping over a cliff and not really working at all.fozzy, did you find that your 1.8T's power curve changed as the actuator wore out?
AndySpecD said:
The return spring on the actuator arm can soften over time so you never develop full boost (the wastegate is always bleeding air from the turbo), there should be an amount of pre-load on the actuator spring. You can normally tighten this up by removing the clip holding the actuator arm to the wastegate, releasing the lock nut and and turning (assuming it is a threaded rod as most are).
^^^ThisI had an MX5 turbo that had 276bhp and it got slower over time.
It had boost control but if the spring on the actuator isn't strong enough it'll open anyway.
Replaced it and FECK ME !
Instead of building boost 5,8,10,12,15psi it was just 7,15psi the actual bhp was the same but the difference in acceleration was tremendous.
wolfsburggolf said:
This contribution is priceless - many thanks redgriff. My next question was going to be "how much difference does a new actuator make", but you've answer it already!
I'm thinking of checking everything - hoses and pipes, rest of turbo etc....but I'm really hoping it is just the remap that has further weakened the spring and thats why it now feels weaker than it initially did after the remap (it was weak before remap anyway)
Out of 10 redgriff, what number represents just how much difference the new actuator made?
Many thanks
In my case - HUGE.I'm thinking of checking everything - hoses and pipes, rest of turbo etc....but I'm really hoping it is just the remap that has further weakened the spring and thats why it now feels weaker than it initially did after the remap (it was weak before remap anyway)
Out of 10 redgriff, what number represents just how much difference the new actuator made?
Many thanks
Easy to see with a boost gauge - how quickly you hit your target psi.
I bought a cheap Ebay one - it only lasted a month so I bought a proper one second time around - expensive for a simple device.
If you are down on overall power that is different to me but I guess it depends on the turbo / engine how much difference it makes.
Got a good little 'turbo / actuator story to contribute too
A few years back, I had a Volvo S40 turbo. Used it lots, racked up loads of miles commuting - great car and already quite quick.
After 4 years or so, with 150,000 miles up - I bought a new car. We decided to keep the Volvo for a bit for shopping trips etc - it wasn't worth a lot by now.
As I wasn't too bothered about it expiring then - I decided to have some fun with it to see what would happen...
I clamped the vacuum pipe from the solenoid to the wastegate actuator by folding it over on itself so it was pinched closed, and securing it with a cable tie. This meant that as the boost built up, the ECU would open the solenoid to put vacuum into the actuator, to activate it, open the wastegate and bleed off boost - but now the vacuum wouldn't actually reach the actuator, so it would stay shut.
I figured that as it was quite old and the spring probably past it's best - as per the comments in this thread, the wastegate would probably open a little anyway against the spring in the actuator and bleed off a little boost, hopefully enough to stop the engine meting down completely...
Well f
k me - the car turned into a missile. I mean really ridiculous power - monster boost spinning the front wheels up in the first two gears hilariously, so that they spun and torque steered everywhere!! You couldn't use full throttle in the low gears really - and in higher gears, full throttle meant monster acceleration.
Great fun - a tuning mod that brought huge results at the cost of a 5p cable tie.
I fuly expected it to die a death soon after - but you know what? It kept going for another TWO YEARS like this - still as strong as ever, we couldn't believe it.
I did use Shell V power all the time, and despite the monster boost, the engine didn't 'pink' at all or give any indication of it not liking all the boost.
In the end, I removed the cable tie mod and sold it on, with over 170k on the clock - still going strong. I never heard back from the delighted 'ebay' purchaser either, so I guess it kept on going!
A few years back, I had a Volvo S40 turbo. Used it lots, racked up loads of miles commuting - great car and already quite quick.
After 4 years or so, with 150,000 miles up - I bought a new car. We decided to keep the Volvo for a bit for shopping trips etc - it wasn't worth a lot by now.
As I wasn't too bothered about it expiring then - I decided to have some fun with it to see what would happen...
I clamped the vacuum pipe from the solenoid to the wastegate actuator by folding it over on itself so it was pinched closed, and securing it with a cable tie. This meant that as the boost built up, the ECU would open the solenoid to put vacuum into the actuator, to activate it, open the wastegate and bleed off boost - but now the vacuum wouldn't actually reach the actuator, so it would stay shut.
I figured that as it was quite old and the spring probably past it's best - as per the comments in this thread, the wastegate would probably open a little anyway against the spring in the actuator and bleed off a little boost, hopefully enough to stop the engine meting down completely...
Well f
k me - the car turned into a missile. I mean really ridiculous power - monster boost spinning the front wheels up in the first two gears hilariously, so that they spun and torque steered everywhere!! You couldn't use full throttle in the low gears really - and in higher gears, full throttle meant monster acceleration.Great fun - a tuning mod that brought huge results at the cost of a 5p cable tie.
I fuly expected it to die a death soon after - but you know what? It kept going for another TWO YEARS like this - still as strong as ever, we couldn't believe it.
I did use Shell V power all the time, and despite the monster boost, the engine didn't 'pink' at all or give any indication of it not liking all the boost.
In the end, I removed the cable tie mod and sold it on, with over 170k on the clock - still going strong. I never heard back from the delighted 'ebay' purchaser either, so I guess it kept on going!
wolfsburggolf said:
CraigyMc said:
My TT had a problem with the wastegate about 60,000 miles into my ownership of it.
Turned out the bracket that located it to the 2.0 lump had failed mechanically. I still have it lying about here somewhere...
C
What sort performance changes did you see Craigy?Turned out the bracket that located it to the 2.0 lump had failed mechanically. I still have it lying about here somewhere...
C
Once it was fixed, the car subsequently did an indicated 161mph here: http://goo.gl/maps/iO4q
It was just faster (back to its old best) everywhere. Very easily noticeable.
I suspect the car was doing closer to 150mph than the indicated 160-odd mph, but it still shows that the thing was in rude health after it was fixed.
C
CraigyMc said:
It was really easy to tell when the thing had failed as the car struggled to pull past about 4000rpm in any gear over 2nd.
Once it was fixed, the car subsequently did an indicated 161mph here: http://goo.gl/maps/iO4q
It was just faster (back to its old best) everywhere. Very easily noticeable.
I suspect the car was doing closer to 150mph than the indicated 160-odd mph, but it still shows that the thing was in rude health after it was fixed.
C
Sweet! Once it was fixed, the car subsequently did an indicated 161mph here: http://goo.gl/maps/iO4q
It was just faster (back to its old best) everywhere. Very easily noticeable.
I suspect the car was doing closer to 150mph than the indicated 160-odd mph, but it still shows that the thing was in rude health after it was fixed.
C
That's what mine does chap. 3.5 - 4k rpm and it's "frown at the dashboard time"! Urrrr..... haha
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