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Wastegate problems with single turbo


gsportcars

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Hi,

I have been having what I am 99% certain, is wastegate problems.

I am currently running a single garrett T66 turbo on an XS power manifold with a 50mm universal HKS style external wastegate.

My problem is that the wastegate seems to be opening early and not only this, it doesn't stay open. It seems to shutter open and closed very rapidly when coming onto boost. I have a screamer pipe and this can be heard while the wastegate is opening and closing. this only starts to happen at about 0.3-0.4bar of boost and gets worse as the boost rises very very slowly. This is with the boost controller set to zero so it is just running off the wastegate spring. I have already checked the manifold and it is fine with no stupidly small holes for the wastgate opening.

When I set the boost on the boost controller to about 80% above standard or so I am able to see about 0.8-0.9 bar of boost before the wastegate starts shuttering again.

I have the vacuum pipe feed on the side of the wastegate and the hole on the top of the wastegate cap is vented to atmosphere.

 

My own theory is that since I changed to this turbo which has a .68 exhaust housing, I think the housing could be too small to flow all the exhaust gases up to 1 bar of boost, so the actual exhaust manifold pressure is becoming enough to start to push the wastegate open on it's own. I know that loads of guys here run .68 exhaust housings but is this at all possible?????

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I have the vacuum pipe feed on the side of the wastegate and the hole on the top of the wastegate cap is vented to atmosphere.

 

I expect this is your problem. The top should feed to the Out port on your boost controller solenoid, the side to the vacuum source on the compressor housing (with a T to the In port on the boost controller)

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I expect this is your problem. The top should feed to the Out port on your boost controller solenoid, the side to the vacuum source on the compressor housing (with a T to the In port on the boost controller)

 

bugger i was gonna say that earlier "but at the risk of being wrong kept stum" learning every day:D

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Just to add, there's two "holes" on the end of the wastegate, the centre one should be blocked off (I think it's for a mounting bracket if you wanted to use one), the one on the outer rim should be the one that goes to the Out on the BC solenoid.

 

bugger i was gonna say that earlier "but at the risk of being wrong kept stum" learning every day:D

 

:D

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I couldn't hold out any longer knowing there was a possible solution to the problem so I just went out and re-plumbed the wastegate as you described and the problem still exists. With it setup like that the wastegate only starts to flutter at around 0.9 bar but the boost just keeps rising after that. It boosted way up to about 1.5 bar before I let off.

 

I must also add that I have already replaced the wastegate as I thought that was the problem but it didn't change. And on our last mapping attempt, my mapper slightly overfuelled the map at anything above 1bar of boost so I could safely try some solutions without worrying about lack of fuelling when boosting.

 

Are you sure thats the only way to do it or maybe even the top should be T-pieced with the vacuum source and into the 'out' port on the soleniod???

This problem is really starting to get to me at this stage as I know there is a solution staring me in the face......somewhere!!! LOL

 

Oh and yes the centre hole is blocked off.

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The plumbing I mentioned is the correct and only way to set it up if you're using a Boost controller.

 

It sounds like you have another problem, as Pig mentions it could well be an issue with the wastegate port not being large enough. There are other posibilities too...

 

Just to get a bit more info, what sort of RPM and gear are you in when the fluttering begins? What RPM and gear did you reach that 1.5 peak boost?

 

Does it build boost smoothly to 0.9 bar (preferably in a higher gear)?

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No it's deffo deffo not the manifold. As mentioned above I did check that as I had read all the posts on here but the opening on the manifold is more that sufficient.

I have just done another search there and found this thread.

http://www.mkivsupra.net/vbb/showthread.php?t=128228&highlight=wastegate+plumbing

 

The diagrams shown there are not the same as I have just tried so I am gonna give it another go according to the diagram. Watch this space LOL...........

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No it's deffo deffo not the manifold. As mentioned above I did check that as I had read all the posts on here but the opening on the manifold is more that sufficient.

I have just done another search there and found this thread.

http://www.mkivsupra.net/vbb/showthread.php?t=128228&highlight=wastegate+plumbing

 

The diagrams shown there are not the same as I have just tried so I am gonna give it another go according to the diagram. Watch this space LOL...........

 

That diagram is the same mate :) Well, at least the same as I was trying to describe :D Probably my description wasn't too clear

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Upon looking at the diagrams again you are infact correct and that is the way i just set it up.

 

As for the RPMs, although I didn't take much notice of that I think it's about 4k or so when it starts. As it sits at the minute the boost rises smoothly until the fluttering (which is quite loud BTW) starts and keeps rising after that very quickly.

 

Another point I didn't mention is that I previously had the XS power turbo fitted and it had a huge 1.15 exhaust housing. Wiht this turbo the problem didn't exist and I also had the wastegate plumbed in differently too.

 

Just to add to the confusion. I am able to slowly climb right through the rev range while staying off positive boost and it is fine. But the very second I open the throttle and the boost comes on the wastegate starts to go bonkers again.

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Another point I didn't mention is that I previously had the XS power turbo fitted and it had a huge 1.15 exhaust housing. Wiht this turbo the problem didn't exist and I also had the wastegate plumbed in differently too.

 

I assume the previous turbo was one of those horrible T04R things - massive exhaust housing and tiny compressor? They struggle to match the stock TT so is hardly going to stress the system.

 

What exactly do you have now? If it's a true 66mm sized compressor then it'll be pushing the system much harder than the previous one which again leads to an exhaust gas flow issue. Also as you said it's only on max boost that problems develop which leans towards a boost related issue. Do you happen to have any pics of the manifold, particularly the collector?

 

Could you also say which gear you are testing in? Ideally something like 4th (on a manual) will give the a nice smooth build to see where problems are developing.

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I didn't take a pic when I changed the turbo the last time but I have seen pics of both good and bad XS power manifolds and in particular one on here that was considerably bad and mine seemed to be perfectly fine when I last looked.

Yeah it was one of those hideous turbos I had before but I always knew it was a temporary solution.

This is the spec of the current turbo I have.

 

COMPRESSOR HOUSING - TO4S .70A/R 4'' INLET 2.5'' OUTLET

 

COMPRESSOR WHEEL - 66MM ( 2.580'' INDUCER 3.584'' EXDUCER)

 

CARTRIDGE - OIL COOLED / 360* THRUST BEARING / JOURNAL BEARING

 

EXHAUST HOUSING - .68A/R TANGENTIAL V-BAND 3'' OUTLET

 

EXHAUST WHEEL - P TRIM

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Though I doubt it's the cause of your issues, can you take a pic of the turbo? Would be good to identify it at least. From what I can find it's either another cheap XS model or a 'proper' Garrett T04S T60-1 turbo (similar to PHR stage 1)

 

Just to take a step back, are you sure this isn't a misfire/overfuel? Is there any real loss of power/smoothness when it occurs?

 

Can you post exact details of the following:

 

Downpipe size

Mid pipe size

cat back exhaust

Wastegate (XS?)

ECU

Mapper

Injectors

Fuel rail

FPR

Fuel pump

Fuel pressure

Spark plug make and model

IC

BOV

 

Also, what sort of AFR's and EGT's are you seeing when the 'fluttering occurs? Any signs of black smoke from the exhaust? Have you checked the IC pipework for potential boost leaks?

 

Just a case of elimination and I think.

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Here is the link to the very turbo that I bought...

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&sspagename=STRK%3AMERFB%3AIID&viewitem=&item=150163183490&rd=1

 

We did initially think it was a missfire (due to ignition as the fuelling stays constant when this happens) but since I have been playing about with it that much and getting varying results with different ways of plumbing in the wastegate I had ruled a missfire out. Since I figure that if it is gonna miss when it comes on boost then it's gonna do it at the same boost and RPM all the time. I have had this problem initially occur at 0.3-0.4bar and then be fine all the way to about 0.8-0.9bar from simply plumbing the wastegate in differently.

I am waiting on a new set of Greddy 9 iridiums to rule out the plugs being the problem. At the minute I have Denso IK24's that came in the engine cause we killed the first set I bought from over fuelling before we could get the car running at all.

 

Right.....for the following

 

Down pipe, mid pipe are straight through 3" diameter. Then splits into 2 x 2.5" pipes for twin exit system. There is no cat and just a straight through centre silencer and twin rear back boxes

This is the wastegate I am using. I have just bought this and it is identical to one that came in the XS power kit that was previously on the car.

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&rd=1&item=140179295955&ssPageName=STRK:MERFB:IID

 

ECU - Autronic SM4...fully standalone.

Mapper - Jonny @ AI Autosport in N.Ireland. Taught by Mark at MADevelopments. I have every faith in Jonny's mapping ability's. He is well known over here.

Injectors - 960cc Delphis

Fuel rail - custom billet aluminium rail

FPR - constant rate FSE adjustable regulator

Fuel pump - Walbro 255lph

Fuel pressure - 3bar with pipe off

Intercooler - XS power

BOV - Blitz supersound

 

The car hasn't been properly mapped yet but Jonny has told me it is running very slightly lean but it should be boosting fine and running with no problems at the current AFR. I don't have exhaust temp readings with this ECU. There is no black smoke at all. I can't see any boost leaks.

 

I don't think boost leaking is the problem as it is over boosting loads as I mentioned but only when the wastegate is plumbed in a certain way. When it is plumbed as before wher the fluttering starts at around 0.3-0.4bar, it struggle to gain boost anywhere above 0.8 bar.

 

When this occurs from what I can tell the engine seems to run smoothly through it and it deffo seems to be just the wastegate that it acting up. In saying this I do notice that the acceleration is pretty poor at the same time.

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- The turbo seems to be a Garrett T60-1 so similar to the PHR stage 1, no issue here

- Exhaust is no restriction, no issue here

- ECU, superb choice, no issue here

- Mapper, No idea, would need a pro to see the map

- Injectors, Far too big for the turbo, but the Motec should control them

- Rail, No idea, but provided it doesn't leak should be fine

- FPR, Appalling problems with their rising rate fpr's, no idea if it's a static one

- Fuel pump, no issue here

- Fuel pressure, 43 psi is a bit high but still within acceptable limits (What does 'with pipe off' mean?)

- XS power IC, not very good but just about works on small turbos

- BOV, should be okay if it's not leaking

 

From what you've said so far it still seems like you have an exhaust flow issue, particularly the flow to the wastegate (since the spec you posted seems there is no problem with the main system). If there is no misfire, no boost leak, no over/under fuel and a distinct lack of power I can't see what else it can be.

 

IMO it's looking likely that either the wastegate is at fault or the supply from the collector. Or a bad map...

 

What gauges do you have in place> AFR, EGT, Boost, Oil pressure ?

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I think I have found the problem.

My boost controller was originally set to actuator mode and not wastegate.

The controller is the Blitz Dual SBC spec R. I did flick the switch on the back to wastegate but I have realised that there is an extra 3pin plug coming from the controller itself that isn't plugged into anything. I assume I need to plug this into something to get the wastegate control to work correctly but there are no other connection there for it and i can't see any other connections on the soleniod box either. Anyone used one of these before who would happen to know what part I am missing???

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Well it seems that STILL isn't the problem!!!!

I have already tried with it set to wastegate and it was still happening. I thought this was because of the extra 3 pin plug not being connected but it turns out that this plug is for a map analyser or some sort of extra that is optional. Definately nothing to do with the wastegate setup. I am now back to square one again!!!!

 

Homer this is the second wastegate I have tried as I already thought that was the problem but it seems to be something else. I only have a boost guage at the minute as the Autronic takes care of everything else. The thing about the dodgy manifold was that the holes on some were too small and not letting enough air escape throught the wastegate. My problem is the opposite as the wastegate is opening too soon due to manifold pressure pushing the valve back. Oh and i'm talking about the vacuum pipe on the top of the regulator that feeds from the inlet manifold.

 

Yeah Wez i tried that but in that case what do I do with the top port on the wastegate??? Vent it off???

 

Ryan I am taking the vacuum feed from an oultet on my intercooler piping close to the turbo. I have already checked this hole to make sure it wasn't blocked and it was fine.

 

Yeah Ernie I felt like a right idiot when I thought of it. Put it down to a rookie mistake but I feel better about myself now knowing that it wasn't the problem after all.

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