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Discussion Starter #1
Hi all.

Got a problems with my blitz VTA DV, it is causing the car to die when dropping back to idle.

I know these can be adjusted, but how?

There is a threaded bolt coming out the top of the valve, will winding this down stiffen the valve and increase the pressure thus stopping it stalling?

Or, is it always going to do this? In which case I will put the OEM valve back on and sell the blitz....

Any thoughts?

Paul
 
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Discussion Starter #2
Paul,
I've just fitted a HKS SSQV to my Evo 6 (because the better half likes to go around scaring people with the noise :D) and have noticed that on occasions the idle will fall off.

After thinking about it, this is my reasoning as to why it happens and what you can do to stop it.

The valve will open under a certain differential pressure between the plenum chamber and the boost pressure. The differential pressure that this occurs at it based upon the strength of the spring in the valve.

When the valve opens normally on throttle close, you have a large difference in pressure, the valve opens and stays open until the boost pressure is relieved.

Due to the fact that you have a large vacuum in the plenum chamber at this point, the valve won't close particularly quickly and so if you go straight to idle after the valve has lifted the valve remains open for a short time and you get extra air leaking backwards through it and causing the idle problem. This will occur with either type of DV but with the OEM item, it doesn't matter because the air has already passed the airflow meter and is accounted for in the fuelling supplied by the ECU.

Strengthening the spring by adjusting the screw may help this by closing the valve slightly earlier and not allowing as much air to leak back in but what I have found is that when you are coming to a stop and idling if you coast in-gear up to a point at which the revs are less than 2,000 rpm and then go into neutral you don't get the idling problem because the dump valve is closed and cannot leak air backwards.

Therefore your options are as follows:

1. Tighten the spring fully and see if this cures the problem of the valve remaining open when there is a large vacuum in the plenum.

2. If this doesn't work then try running around and before idling, coast in-gear for a short time to make sure that the dump valve is closed before going to idle.

Hope this helps

Andy
 
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Discussion Starter #3
Thanks for that Andy, those are my exact thoughts.

If I drop it to idle from low RPM, it does not stall. It is, as you say, when dropping to idle from high RPM (on boost) that the valve causes the car to die......

This evening I will tighten the valve down all the way and take it for a blast. I am sure this will cure the problem, but I will loose some low RPM whooshing :( ;) .......

I will post my results in the morning (or a 'for sale' ad for the blitx ;) )

Thanks again mate, great explaination

Paul
 
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Discussion Starter #4
My HKS DV does this as well, but only now and again..

POC how you finding the evo mate? What your thoughts on it?
 
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Discussion Starter #5
Paul,
I guess that from your For Sale thread that the screw didn't solve the problem then?
It really is just as simple as making sure that when you are going to idle that you don't drop the revs from greater than 3,000 rpm before pressing the clutch. Do this and you won't have any idle problems at all.

Andy
 
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Discussion Starter #6
HI Andy, I have tried that mate, but even stalling once every now and then is getting on my tits.....

Has to go I am afraid!

Cheers

Paul
 
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Discussion Starter #7
POC, fit a hks idle stabiliser, cost about £120. Sorted mine out, dont have to worry about what revs you drop from then!:)
 
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Discussion Starter #8
poc i bought an atmospheric but the guy was a professional at kenny browns so he didnt fit it so what he is doing i think is making pipes that would let excess air out i think coz evo's r made fo recircular dump valves, really get it checked out from tony at ralliart mate he would help.

let me get mines fitted next week then we will see how it goes but its not recommened to put an atmospheric one
 
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Discussion Starter #9
Andy,
Are there any power differences you noticed after installing the HKS SSQV? I was thinking about buying this product; however, I been told that no significance difference is seen after intalling the unit...only that the sound is much louder :D Can you give me any feedback?

Thanks
 
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Discussion Starter #11
Torque,
No power differences whatsoever just a nice loud whoosh when you change gear.
We got it because Miss_RSX likes to go around scaring old people by changing gear as you go past them. :D:D:D

Andy
 
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Discussion Starter #13
I have just ordered a Blitz dump valve for the Evo 1. After reading so much about them I'm concerned that it will be more hastle than its worth. Where can the HKS idle stabiliser be bought and would it work with Blitz DD as well as HKS ones?

Shaiz
 
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Discussion Starter #14
I would wiat until you get the Dv then see how its goes.

I fitted a Forge VTA BOV last month with no problems at all.

However i fitted a Blitz NUR spec exhaust this week and ever since i`ve been suffering very slightly with idle problems.I say very slightly as it is very slight, not enough for me to do anything about it, but there has been an idle issue(at times) since the exhaust was fitted.

Rich.
 
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Discussion Starter #15
i fitted my HKS SSQV a few months ago......not one problem.....
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from the sound of it i'm just lucky?!..but i do find it hard to believe that this product would be sold (that does not do much more really than give some aural pleasure - to my knowledge) and then has another product sold to fix the problems of the first?!
 
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Discussion Starter #16
like richw says...its more than likely a combination of UGs that may cause the problem...
 
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Discussion Starter #18
DV was removed on Sunday, std re-circ fitted, all problems now resolved and the car feels a little quicker :D

Happy man now.

Paul
 
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Discussion Starter #19
I fitted a HKS SSBOV about 3 weeks ago the only problem I had was the idle after the trigger hose filter blew its self apart.
This has now been replaced with a heavier duty filter I'll post a pic if anyone wants to see it!

My AFC sorts out the tickover and it has only gone to stall once but heel and amp; toe stoped it:D

Also on really quick gear changes you do notice a more immediate responce to throttle presure.

Jeremy
 
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