Bov / Recirc issue on a VVTi - this is really doing my head in...! please help.

[Mike B]

Hi All,

 

I'm having issues with my recirc system.

It's set up as a recirc valve and I can't make it work for the life of me, still keeps pushing air past the compressor in little squeaky noises under lift off) and I'm totally out of suggestions...

 

Story so far;

- Existing Recirc valve stops working -

- So I took it off and lubed it up (where the piston goes through the housing, and generally cleaned it up) Worked for a day or two then stopped working again.

- Bought a brand new HKS SSQV from fleabay, which arrives, looked fine, but wouldn't work, and then I found out that it was a fake.

- So, bought another HKS SSQV from the HKS importers (TDI) and fitted that. Still doesn't work.

 

Now I've tried plumbing it in to two different places on the manifold - just behind the throttle body (A on the pic) and at the rear of the manifold (B) on the pic.

I've tried different diameters and types of hose, but no joy,

 

Any Suggestions?

 

My own thoughts are that;

- I'm plugging it in somewhere that is not causing activation

(but all taps seem to lead to the intake chamber as far as I can see)

 

- the electronic throttle (VVTI) is not shutting fast enough to really get a good vacuum

(these can vary between models, and mine is not the sharpest of them)

 

- there is a manifold leak that is not letting the manifold build a sufficient vacuum to activate

(but if I so much as pull one hose off, it raises the engine revs so far that the throttle cannot compensate - (held on etcs-i with syvecs))

 

- the diaphragm is too aggressive (original has an adjuster spring and used to work, but no more. HKS units have no adjustment at all).

 

I can log manifold pressure with Syvecs to see what it is actually doing, but for god's sake, it's a dump valve, not a rocketship. Is it too much to ask for silence between gear changes?? (Turbo is a T67 DBB)

please help!

it MUST be something stupidly simple.

 

Should I plumb it into every port on the manifold? ha ha

 

:-(

Edited February 20, 2015 by Mike B
sp (see edit history)

[Scott]

Is the BOV activating at all? Does it suppress the sound at lower revs, is it only on high boost that it sounds? The locations you have specified for activation are fine. A is the original power steering valve connection and B is the rear of the manifold where my boost gauge and FPR are connected to.

 

If the BOV is activating it may just not allow enough flow to stop it from surging a little past the compressor. Have you thought about a HKS super racing one? That's the one I have, but I've not tried it in anger yet. I won't be using it in recirculation mode either.

[Mike B]

I even went so far as to take the valve off completely and blank the manifold off. It sounds the same fitted and not.

It squeaks under the lightest lift off, I'm certain it's not working, as the old original one did when I had stripped and lubed it.

The old one does have the lightest activation (resistance to push back with your hand), so assume it will activate the easiest of the three.

Deliberately went for the SSQV as it said it could light release (sequential) hence helping activate under light release...

[Mike B]

Hi All,

Next update -

Today, I;

 

- removed the recirc piping to the intake and blanked it off - I tried this incase the recirc piping was causing a pinch/restriction stopping the valve from working to it's optimum. In my mind I should also be able to hear the dump valve dump more...

 

- re routed the activation vacuum pipe from the SSQV to the intake manifold using the stiffest pipe I have at the best diameter directly to the manifold take off behind the throttle body (this is where I have had the most success with it working before.

 

Then I went to test it.

After a few miles and a few cycles it started to dampen a bit of the flutter back through the turbo, but it's still not working as i would consider it should.

The flutter is still there, and really - I cant hear the valve releasing pressure - no "pshhh" that I can hear - maybe your ears can...

I made two vids of it... Would someone with a similar system like to take a listen and tell me what they think?

T67...

and my god the roads are greasy!

 

http://www.vimeo.com/120283327

http://www.vimeo.com/120284036

http://www.vimeo.com/120283327

http://www.vimeo.com/120284036

 

and..

Here is an old video of the car - admittedly with a different turbo - from marham, Maybe a GT4088, with no hint of flutter...

Thus is where i want to be with the system, not chattering every time I lift off....

(Oh and I wouldn't say no to a nice run round a summery Marham either! )

 

Edited February 22, 2015 by Mike B (see edit history)

[Mike B]

and again, another old video with ZERO noise between gear changes...

 

[Scott]

That really doesn't sound right. You should be able to watch the BOV activate with the bonnet open. It won't woosh, but the vac from the engine will pull the valve open if you give it some revs then let off. I understand you're vvti but if someone helped it should work fine. It will at least diagnose the BOV itself.

[Mike B]

That really doesn't sound right. You should be able to watch the BOV activate with the bonnet open. It won't woosh, but the vac from the engine will pull the valve open if you give it some revs then let off. I understand you're vvti but if someone helped it should work fine. It will at least diagnose the BOV itself.

 

That's very true,

I'll have a go at that, mind you, I have 3 Valves and none of them work so far

 

What do you think about the vacuum levels on lift off, looking at the gauge ?

I'm wondering if the syvecs mapping of the throttle has it shut 100% on lift off, for if it kept the throttle open a fraction its possible that the vacuum would not be strong enough.

 

I can't be sure but it's possible that I've had this problem since syvecs replaced the hks+ stock throttle system

Edited February 22, 2015 by Mike B (see edit history)

[CanisLupus]

The Vacuum is more than enough to open a BOV which is working correct and adjusted(if adjusting is available) correct.

[Mike B]

The Vacuum is more than enough to open a BOV which is working correct and adjusted(if adjusting is available) correct.

 

Yup, I concur..

I did some googling...

The readings are good, way more than enough vacuum.

Now I know (thanks Scott) they will activate at idle with throttle blips I'm going to play musical valves and musical takeoff points around the manifold until I get the best result, then try fitting that combo into a driving configuration.

[Scott]

Yeah looking at the gauge you're bang on what it should be. Very little vacuum in the grand scheme of things will open the valve, never mind a bar below atmospheric

 

Investigating the valve with your eyes is definitely the way to go. I can get a bit of a woosh out of mine just by playing with the throttle, it's not full blown, but it's enough for fault finding.

[Mike B]

Update on this,

I tested the 2 of the three valve's on the manifold, revving the engine at idle (it's possible still on the throttle body of the vvti)

both the old valve and the copy hks work perfectly on all manifold locations.

 

I could not test the new hks genuine fitted in place as I was on my own and my snap ring pliers have broken attempting to remove it.

I'll have new pliers tomorrow and will test the valve in situ with a glamorous assistant.

 

My instinct is that it is activating - but why it's still causing chatter, I have no idea.

[Scott]

I would try the BOV as it sits without the recirc pipe attached. So that it vents to atmosphere. That way when you're out a run you should be able to hear a proper whoosh from it.

 

If you hear a loud BOV whoosh and the turbo flutter then the BOV doesn't flow enough and you'll need an HKS super racing BOV.

[Mike B]

Today I managed to ascertain that the brand new HKS valve, fitted in place is working properly - I can feel it open under idle. Road test with the recirc pipes off (just the nozzle of the valve to atmosphere) does indeed stop chatter on small gear changes, but give it anything with a close to meaty flow and it makes absolutely no difference to the chatter back through the turbo.

 

I can therefore only conclude that the valve is unable to flow enough gas to work properly.

would you concur?

 

The old valve (which seems like it has a bigger piston head than the HKS ssqv I am currently using) worked on a GT35R DBB turbo. I have stripped it down - diaphragm is fine, I have silicon lubed the piston, and it's tested as working on the car in position, so I will fit this and see if it makes any difference.

 

If not, then what are my options?

Bigger race valve, or maybe fit an auxiliary valve somewhere else?

[CanisLupus]

Can you adjust it?

If not get a Turbosmart Raceport or Tial Q with the correct spring for your idle vacuum. Will work like a charm

[Scott]

Definitely sounds like it's struggling with the flow. Single turbo's generally need the Racing BOVs from HKS to flow enough and keep it recirculating, so I would keep an eye out for one of those

 

- - - Updated - - -

 

This one....

 

[Mike B]

This one....

http://www.3si.org/forum/attachments/f35/66836d1185848008-racing-typeii-blow-off-valve-bov-hks-racing-06-300l.jpg

 

That's hilarious!

 

I was wondering what the bigger original dump valve was. When Terry built the car it was littered in HKS, so no surprise I guess. Anyway, have a look at the pic below. This is the original valve that I started with!. Worked on the GT35 DBB and the GT4088, but the T67 DBB, it chatters. Anyway, I stripped it, silicon lubed it (feels smoother now) and I'll refit it venting to atmos, with the connection pipe removed so as to maximise the exit aperture, and see how I get on.

[Chris Wilson]

The most reliable recirculation valves, and often to be found for a couple of quid in scrap yards, are the Bosch ones fitted to many Saab turbos, Cosworth Sierra turbos, some Renault turbos, blah blah. Dull looking in black plastic, they won't win a show and shine, but never give trouble and are small, light and neat. You could of course do what I do and NEVER run a valve of any sort on turbo engines. You may get some noise, but zero to go wrong, pay for or plumb in.

[Mike B]

Just fitted the old cleaned and re-lube'd valve and it's the best of the three.

It catches all mild boost, but when you start flowing 1 bar the turbo gets one chat off before it falls silent.

That said, the one thing I did notice now I have removed all the piping from the end of the valve is just how much gas flows out of the pipe over a second after the throttle plate closes. It's not just a short sharp pressure drop, it's a gradual and lengthy loss of pressure and once you hear it, you realise just how much gas there is inside the pipework and intercooler to come out of that aperture.

I think that if I want to make it silent the valve will have to go very close to the compressor where the pressure is highest, and it's closest to the bit of kit it's supposed to be suppressing and protecting.

 

Thanks Chris - but I can't live with a chirping turbo on a roadcar, track is fine, but i'm a lover of discretion these days.

You really think a older stock valve will flow enough gas? the hks "race" type 2 I have is better than ssqv, but it's not enough.

Oddly, after looking at both types, I'm inclined to think that HKS are designing fashion item rather than a functional piece of technology :-/

or maybe our cars are just not normal.

[T2 MSW]

If you have 2 could you not fit one each Side, One right up to the intake and one close to the compressor. Surely that will flow enough air and catch anything pre and post intercooler??

[Mike B]

If you have 2 could you not fit one each Side, One right up to the intake and one close to the compressor.

I think that's a plan.

It's not like I don't have enough.

;-)

[Scott]

Ha, at least that explains why the original one was the best

 

I would definitely try hooking up 2 of them. It could make the difference you are after. It may be tricky to get it re-circulating if they are so far apart though. That's going to take a lot of extra pipework. If they were right next to each other you could y-piece them into a return pipe.

[T2 MSW]

Oh yeah re-circ is going to be difficult. Just put up with the ace noise

[Mike B]

I ordered an extra boss today - The original plumbing is neat - will try and make the new plumbing extra neat too.

 

I just cant abide that noise :-(

I'm sorry, but on a public road I die a thousand deaths every time it goes off.

For me it's like having tourettes at your grandparents bbq.

 

My car was so loud when I bought it - full 4" system and screamer pipes.

It's now 3" with twin boxes, internal wastegate and sound insulation. Civilisation is it's middle name.

[Morzy2k5]

Why are you insisting its silent.Why don't you like the surge noise may I ask?

[Scott]

Why are you insisting its silent.Why don't you like the surge noise may I ask?

 

Probably for the reasons he's stipulated numerous times in this very thread