Wastegate problems with single turbo

[gsportcars]

Don't worry, new gauges are already high on my priority list.

[Guest Endastrobin]

I dont know, but i have friends that have problems with the Hks copy wastegates

That the Valve stays open or Else.

I now alot of people that Turns the axel and just grind the axel.

The quality is not the best at those cheap Wastegates.

 

Buy a Tial or a real Hks and you get real quality.

its kind of importent to have a functional wastegate:)

[gsportcars]

I went and had a chat with a couple of people simply to get a fresh perspective as I have been thinking about this far too hard.

After realising that my idle control valve was not set to fully close when the throttle was open I knew that was a boost leak for sure. So until I can get the laptop on the reset this correctly I decided to just block the valve off completely to see if it solved the problem. Needless to say it didn't change a thing!!!!!!

I was pretty certain this was the cause but I am once again stumped. I am still going to check for more boost leaks later though but after thinking about this I really don't see how it could cause this problem. For a boost leak to cause this the car would first of all need to reach full boost so the wastegate would initially open. then obviously if there is a leak, the boost would drop and the wastegate would close again and so on. But with this the wastegate is starting to open an around 0.3bar which is far too low.

The way I see it, the wastegate can only open from boost pressure through the vacuum pipes or excess exhaust manifold pressure or a combination of both.

I do think it is a combination of both that is causing it as the boost pressure is to little on it's own and there is no reason that I should be having excess exhaust pressure as I have a straight through system.

some people have also suggested trying a heavier spring in the wastegate but again I don't see how this could solve anything. All that will do is simply make the shuttering start at a higher boost level

 

I am once again back to pulling my hair out over this.

[kieren1234]

I agree with trying a bigger wategate spring, which spring is in their at the moment ??

 

Get a spring that is just under what psi you want to run, then if you want to up it, do so with the use of a boost controller. I would try and run off the wastegate spring alone first and this would eliminate the boost controller from the prolem as it may be plumbed in wonrg.

[gsportcars]

Yes I did try running off the spring with no controller and it did the exact same thing. If you read back through the thread you will see all the different things I have tried which is why I am completey out of ideas. I really don't see what could be causing it. The wastegate setup is an incredibly simple setup. there is no reason why it shouldn't be operating with out problems. Even if I had a 0.1bar spring for talks sake, the wastegate should still open and stay open at 0.1bar. so I don't see what a heavier spring would achieve.

For the record I don't know what spring is in their now but I did have a 1bar spring in the first wastegate I tried and it did the exact same thing.

[kieren1234]

It will be interesting to see the outcome of this, the main reason being is that i have a "similar" problem.

 

What happens when your car is just idling, is the wastegate completely shut?? Only reason i ask is on the na-t i built is opened on idle for some reason.

[gsportcars]

Do you have the same HKS copy wastegate??

I had that problem on my original wastegate and it was due to the valve not lining up correctly with the flange when I bolted it to the manifold. When I removed it I realised that the flange/sandwich plate (the bit that has a groove in it for the valve to close into) was sitting off centre when the 4 bolts were pushed through. I had to drill out the 4 outer holes to let the flange slide over into the centre of the wastegate valve. Before doing this the valve couldn't seal properly all the way around the circumference but once it was centred it was able to fully seal. It sounded like I had a massive exhaust blowout until it was sorted. I expect that is the problem you are having. This is something completely different though. FFS......

[kieren1234]

Do you have the same HKS copy wastegate??

I had that problem on my original wastegate and it was due to the valve not lining up correctly with the flange when I bolted it to the manifold. When I removed it I realised that the flange/sandwich plate (the bit that has a groove in it for the valve to close into) was sitting off centre when the 4 bolts were pushed through. I had to drill out the 4 outer holes to let the flange slide over into the centre of the wastegate valve. Before doing this the valve couldn't seal properly all the way around the circumference but once it was centred it was able to fully seal. It sounded like I had a massive exhaust blowout until it was sorted. I expect that is the problem you are having. This is something completely different though. FFS......

 

 

That what you have described is exactly the problem i am having, may have to check this but i ordered another one anyway. Mine also sounds like a massive exhaust leak. Thansk for sorting that for me mate, shame i cant help you sort you're problem but taking to a garage specialist may be the best bet.

[gsportcars]

If that sounds familiar then it is pretty much deffo the prob. You will not need another wastegate but just need the 4 outer holes drilled or widened as I said. There is a lip on the ring of the flange which has to actually slip into the circular ring of the wastegate body. if this doesn't slide into place then the flange won't be centred when bolted up. you need to clamp the flange down while it's off the car so that you know it will fit right when finally bolted up.

 

BTW.....I am still wide open to any suggestions about my wastegate problems.........................

[Ian C]

OK once you've tried the normal investigative stuff you have to try and get as much behaviour data as you can under different circumstances. I'd go for "how does it behave with the wastegate permanently open and permanently shut?"

 

So disconnect all the vac hoses from the wastegate and drive carefully, watching boost like a hawk and controlling it with the right foot, and see how it behaves then. Following that, try and open the actuator somehow (don't ask me how) and see how it behaves.

 

This info could implicate or rule out the wastegate diaphragm, the boost controller, vac hoses, wastegate plunger etc etc.

 

-Ian

[gsportcars]

Yeah man I did previously try it with no pipes connested to the wastegate and it overboosts as expected but the shuttering still happens although it doesn't start until around 0.8-0.9bar. It then shutters all the way up to 1.5bar++++

With the pipes back on again the shuttering happens at 0.3bar again as I expect the added boost is helping force the valve open along with the exhaust manifold pressure.

It is for this exact reason that I am pretty sure the problem is due to the smaller exhaust housing on the turbo not being able to flow the air out quick enough hence causing exhaust manifold pressure which is pushin the valve open on it's own.

I am going to try the other spring from the old wastegate as I know for sure that it is a 1bar spring and I am not certain that the current spring is strong enough.

[TLicense]

I don't think it's a boost leak. The reason being is that unless it's a monster of a boost leak, which I think you would have discovered already, then it would still make positive boost, and would do it fairly smoothly. Just the ultimate figure would be lower than expected and your EGT's would be high.

 

This stuttering that you're describing, what sort of frequency does it occur?

 

To be totally honest, I'm kinda thinking it could be a misfire. A quick check would be to change the plugs and see if that improves matters on the stuttering front. When you do though, try to keep the boost below 1.2 bar and see how she drives.

[gsportcars]

The problem is definately the wastegate as I can clearly hear it shuttering open and closed via the screamer pipe. If I listen closely, the engine note is fine and the engine can be heard running smoothly while the wastegate shutters. I did have a missfire before hand and it was immediately noticable as a missfire because the engine would stutter and hesitate and back fire etc etc. this is completely different. I haven't yet properly done a test for and boost leaks but simply just checked that all the clamps were tight etc so I am going to test it using a bike tube to see if I am getting any pressure loss and more importantly where it is escaping.

I am, believe it or not, still waiting on a set of new plugs anyway just to be sure but they have been lost in the post somewhere.

 

On the shuttering frequency... I did think of this but it is very hard to get an idea of this. It does sound like it rises and falls with the engine speed but this could also just seem like this because the exhaust gas is travelling through the wastegate quicker when the revs rise. It is difficult to tell if the shuttering is going quicker or if it is simply the sound is changing pitch from the change in engine speed.

[TLicense]

Just because you can hear the wastegate opening and closing, doesn't mean that's the problem. The wastegate, put very simply is a valve. It will only react to the pressure that it sees. From what you've described, it would suggest that you've got pressure surging, causing the wastegate to open and then the wastegate is opening and letting the pressure die off, which closes the wastegate and you go into a cycle. What you need to find is why it's surging, which could be down to a number of reasons.

It could be down to a boost leak, but if you know the location of all the clamps from the turbine to the throttle body and have checked them and they are tight, then I doubt very much that it will be that. Don't assume that just because you did them up tight, that they still are. (I fell for that one!)

You're sure that the turbo itself is definitely the right one for the job? It's not too small and is surging under boost pressure or anything daft like that (unlikely I should imagine, but one to potentially think about)

You've checked off any ignition problems which can also cause a stuttering, which could lead to a surge.

Is there anyway you can supply a constant pressure to the wastegate port and keep it open and see if it still exhibits the stuttering? That would definitely tell you if it was the wastegate or not.

[gsportcars]

My problem is exactly as you say....pressure surging. I know that is exactly what is happening but I can't find the reason as to why the wastegate is shuttering or surging.

I don't think it's a boost leak either because if it was then surely the shuttering would stop when I disconnect all vacuum pipes from the wastegate as there would be no boost pressure at all on the diaphram???? This surging happens ALL the time but the only thing I can do is make it happen at 0.8-0.9bar of boost instead of 0.3-0.4bar of boost but to do this I have to plumb the wastegate in wrongly in order to apply the boost pressure to the opposite side of the diaphram. This just keeps the valve closed for longer. When setup like this the car obviously overboosts loads as the wastegate can't stay open.

My turbo is a Garret T66 turbo with a .68 exhaust housing. I thought this may be the reason but plenty of people on here run that size of housing with no probs.

Although I haven't rulled out the spark plugs I don't see how they could cause the surge.

with the wastegate set up properly the surging occurs at 0.3-0.4bar. This would mean that the car would have to missfire at that boost to kick off the surging cycle. But when I have had the wastegate setup incorrectly and it boosts to 0.8-0.9bar, I never get any missfire at 0.3-0.4bar. If it was this that was causing it then I should still get the missfire at the lower boost although the wastegate may not surge as it has the extra pressure holding it closed.

 

I also don't see how keeping the wastegate open would tell me anything even if I knew how.

I don't mean to sound negative about any suggestions people give at all just incase it seems like that. It is simply that I have tried to take everything into account and have tried so many things. I know that a wastegate is an incredibly simple device which makes it even harder to understand why it's going wrong.

[Mike B]

Holy cow, I have ben reading this thread and it sounds like a nightmare. My condolences. When I moved down to a .68 housing on the 4088r I was advised to watch carefully for surging by Terry S who had been through a few turbos, including some of the cheap ebay ones, and had experience of this problem. Thanksfully I had no sign of it on mine... He told me that the turbo has to be matched for the engine, and had seen surges on a lot of the aftermarket companes mainstream turbos, and turbos that the "experts" had recomended him.

 

Do you have another turbo you can try? or a bigger turbine housing? It sounds like you have ruled everything else out.

[gsportcars]

I still have the exhaust housing from my old XS power turbo which is a huge 1.15 size but i am not entirely certain it will fit my current turbo. As you say, it could be worth a try.

[Mike B]

I have not experienced it, but it sounds just like compressor surge/stall. Not good for the turbo either.

 

Possibility that just because one car does not do it with the same turbo as yours, your turbo may, but at least you can try it and see if it works. You'll have to wait a while for it to spool though , and watch your engine/afr's, I guess you haven't been able to map yet anyway if it's not working?

 

I'm also not 100% convinced that changing the AR will rule this problem out, as the problem (if it is surge) may be incompatability of the cold side too, hence why I suggested changing to completely different tubby.

 

I just swapped my housing twice now and it's an annoying fiddley job; sorry!

[gsportcars]

The more I think about this the more I am convinced that it is deffo the exhaust manifold pressure that is pushing the wastegate open. This is because as I mentioned above, I have tried it with no pipes connected to the wastegate and it still happens, so there is nothing else that could be causing it.

What I still don't see is how the manifold could possibly be building up that amount of pressure. I know how hard it is to push back a wastegate valve as the spring inside is already pre-loaded and under tension. I'm a big lad and it was a struggle to get it to move. Also taking into account the fact that there is a 3" hole/turbine for the gases to escape through, I struggle to see how that amount of pressure could be built up and also built up so quickly.

 

Another thing as I mentioned before was that I know that plenty of people have the same or nearly the same size and spec of turbo as me and they run with no problems so I don't see why I should have to go for a bigger housing because of this, so is there any other method of solving this problem without changing the housing size???

Are there different types of housing design that are the same size but allow greater flow???

And to drag this on another bit lol.....How does the compressor side affect this? the only way can imagine this being a problem is if the compressor wheel to aggressive and tries to flow the air in too quick. I expect this would make the wheel harder to spin and therefore slow down the turbine wheel at the same time. But again I still cannot see it getting to the point that is causes such a large amount of back pressure in the exhaust manifold?????

[Mike B]

How I understand it (someone will correct me, but it is as it was explained to me)

 

The turbo must be roughly matched to your engine - if not you get an imbalance, ie wrong turbo,

which, when it spools it forces too much air into the mouth of the engine too quick, and it can't swallow it.

Pressure builds, the engine produces lots of horsepower, so much that wastegate opens, but to no avail as the pressure in the intake continues to grow until the compressor wheel stalls, before the wastegate can dull the power from to the turbine and reduce the intake (boost) pressure...

so then as it stalls.. no power, wastegate shuts and the cycle starts again.

 

Casuses can be too small a housing, spinning the turbine up too quickly, or crapy turbo that is unstable. You use .81, and that should be fine, hence I suggested turbo swap.

 

In this situation the wastegate can not have any effect on the problem, to cause or cure, as it is the incompatability of the turbo that causes the oscillation.

 

I'm no expert on this... but this is my understanding.. and it seems to fit your problems..

 

Has anyone here had problems with surge and what are their experiences?

 

here is something I just pulled off the net "What happens when you upgrade to a larger inducer while retaining the same exducer? The most notable change is more airflow capability; since the turbo is taking a bigger "bite" of air in every revolution, it can obviously "spit out" more air as well. Gee, more airflow aounds great... so why not go to the biggest inducer you can find? Because that creates two main problems, one much more important than the other. The smaller problem--really it's just a nuisance--is the turbo will now have a little more lag during spoolup (because the bigger wheel weighs more, plus it has to do more work with each revolution, etc). While this extra lag might not be noticed on a dyno--all the bystanders will be oohing and ahhing at the huge top-end horsepower such a turbo would produce--it would make for dissatisfaction in your day-to-day drive and could even cause you to lose a drag race to a car with less peak horsepower but more area "under the curve" due to his turbo that spools sooner. The real trouble with a large inducer increase but no exducer increase, though, is it makes the turbo much more likely to surge. Surge is the situation when the compressor "spits out" more air than the engine can swallow, which causes a backup of air at the intake and it actually creates reverse-flowing pressure waves that can be very damaging to the turbo. You want to avoid surge at all costs."

 

http://www.turbominivan.com/tech/turbo201.htm

[Mike B]

come to think about it if the oscillation is very rapid, it may not be this... kind of why I wished someone who has experienced surge would comment, as I have no first hand knowledge. Might be worth describing your syptoms to a turbo expert to at least rule it out? Turbo technics??

[Mike B]

ah ha!!

 

http://www.youtube.com/watch?v=OuNTnA5A2Fo&feature=related

 

but i have no sound on my computer!!! lol

 

anything like this?

 

or maybe you just have a potatoe up your exhaust from the neighbour.

[gsportcars]

It's very hard to tell as I don't think that car has a screamer pipe and mine does but it doesn't really sound anything like that at all. I am able to hold on the throttle while this happens but instead of the boost rising to it's set limit it doesn't as the wastegate keeps shuttering very rapidly. Als when I let off I don't get the wastegate chatter anymore as I expect the wastegate has only ever opened enough to relieve the exhaust manifold pressure and then closes again. If I understand it correctly the wastegate chatter comes from the valve bouncing closed again from being fully open when you let off the throttle.

 

Anyway you have just gave me an obvious idea. I am gonna get a quick vid on the camera phone to let you guys here it to see if it helps any....

[kieren1234]

Good idea mate, take a video then people will know exactly what you mean.

[Mike B]

the wastegate chatter comes from the valve bouncing closed again from being fully open when you let off the throttle.

 

it does make a noise, but it's a very high frequency and you would be mistaken for not noticing it. I can hear mine more now that it is plummed into the main exhaust system, when it was on a screamer pipe I could hear nothing but the exhaust note.