boost problem with dawes device

[Perrin21]

hiya all, had my boost controller fitted today but we noticed some problems, first was a problem spikey picked up on with my turbo inlet leaking due to a knackered bolt. Quickly fixed. The other problem is its nit holding boost properly.

without the device fitted the car boosted to a perfect 0.7 bar and did not fluctuate. With the device fitted the results are inconsistent. The car boosts to 1.2 bar then boost falls off to 0.7ish , other times it maxes at 1.0 bar and drops off to 0.7. I've also noticed it go over 1.2 bar briefly and again drops off. Any ideas?

 

[Gaz gtiR]

ive had this problem with 5 turbos & punto gt's & turbo blew a week after this started! so turbo could be on its last legs?? this could be another problem tho... im just saying keep an eye on your turbo check shaft for play & smoke when backing off the throtle.

 

[Spikey]

We did find a lot of oil in the Turbo outlet. But before scaring him i wanted to do more tests but he had no time.

 

[Gaz gtiR]

yep i wasnt meanin to scare him lol. its just when he said he's put it back to standard boost & it dousnt back off 0.7 bar but when hes upped the boost its backing off. its exactly the same sort of symptoms i had! it could well be something else! but how else would oil get in the outlet?? i hope its nothing major tho :?

 

[williams]

Pull actuator vacum off and see what it boosts to. That will rule. Out the actuator. With the dawes on its lowest boost setting is it running as standard. I would check actuator 1st though, then buy an avcr lol.

 

[Perrin21]

Pull actuator vacum off and see what it boosts to. That will rule. Out the actuator. With the dawes on its lowest boost setting is it running as standard. I would check actuator 1st though, then buy an avcr lol.

I currently have a forge actuator on, without the vacuume hose fitted, won't it overboost and break something?

 

[PobodY]

Not if it's knackered... but potentially yes, that gives you unlimited boost (until the venturi effect just pulls the wastegate open).

I've never had a problem with my dawes device; it's been far more reliable than my EVC ever was. Hits the set boost and trails-off about 0.1bar as the revs keep increasing. Never goes over (like the bleed valve that was originally in there did, or the EVC when the solenoid got stuck), never goes wrong.

The alarm bell to me is that you've already had to fix one problem with the turbo (albeit a small one).

 

[williams]

Or you could check it the safe way with a foot pump or compressor on actuator to see what pressure it opens at.

 

[Perrin21]

I'm still hopeful the turbo is ok. Not had any real issues so far and the car pulls strong without the Dawes valve. It has a small hole in it. Is that normal?

 

[Perrin21]

I am going to order the spring kit for my forge actuator. I'm guessing its a piston type. Are they all the same for standard turbo? What is the best spring to use? Is this the best solution to rule out the actuator?

 

[williams]

I'd expect that hole bleeds some boost off so you can run more. Boost than wastegate pressure?

 

[PobodY]

I'd expect that hole bleeds some boost off so you can run more. Boost than wastegate pressure?

I'm not entirely sure why it has the hole, but it's not bleeding anything off; the spring holds a bearing against the body so it shows the actuator no boost until the set point is reached (in the same way an electronic controller holds the solenoid closed until the set point is reached). - I suspect it's simply so that there is no back-pressure on the bearing which might prevent it from opening; obviously if it was a closed system the boost would have to compress the air within it first before it would open and equalise (thus bouncing around).

 

[Perrin21]

I have ordered a new actuator spring that supports 12.5 psi to 17.0 psi . There's no way the existing actuator spring would be compatible as forge do 4 different ones. Fingers crossed its this.

 

[williams]

Electronic controllers let some of the pressure bleed off, for example if you want to run 1 bar on a 0.7 bar actuator, the solenoid will bleed off 0.3 bar, + the 0.7 bar to open wastegate gives you 1 bar.

 

[Perrin21]

Electronic controllers let some of the pressure bleed off, for example if you want to run 1 bar on a 0.7 bar actuator, the solenoid will bleed off 0.3 bar, + the 0.7 bar to open wastegate gives you 1 bar.

Do you think the spring seems like a likely cause of the problem?

 

[PobodY]

Electronic controllers let some of the pressure bleed off, for example if you want to run 1 bar on a 0.7 bar actuator, the solenoid will bleed off 0.3 bar, + the 0.7 bar to open wastegate gives you 1 bar.

No they don't.

The standard Nissan solenoid does that (you'll notice it has a bleed port that goes back to the inlet pipework), but none of the more expensive ones will do that; they simply stay shut until the required boost level is achieved, then open. It's how they justify their "builds boost quicker" claim because there's no creeping of the wastegate as you approach the required boost.

 

[Spikey]

And this is why i say no no to a bleed valve type. electronic ones all the way

 

[MarkTurbo]

I'm not entirely sure why it has the hole, but it's not bleeding anything off

Yes it is!

 

[Perrin21]

I'm thinking it might just be better to fit a stronger spring in the actuator rated to 1.15 bar and remove the Dawes device, wouldn't this be better?

 

[PobodY]

Yes it is!

How? I don't mean that to sound like a rude question; it's quite honest.
If the valve is closed how is it bleeding boost off? - I can see that once it's opened some will escape through the hole, but that's somewhat immaterial if you've reached the set-point and the actuator has now opened; or is that what you mean?

It's better to have some kind of controller and the actuator; as I said earlier, without the controller the actuator starts to creep open as the boost approaches the set point... or so I understood it. Maybe I've got this all wrong after all.