Dawes & Needle question...

[Hodge]

Got a quick question for those who have fine-tuned their dawes and needle valves...
Can altering only the dawes valve, stuff up the whole setup? What I mean is, I turned my dawes valve half a turn back, without touching the needle valve, and it threw the whole thing out of whack. Now it's sluggish, in 4th and 5th like it once used to be. Mudski set this up for me last time but hes away at the moment.

I cannot get it back to where it was, no matter how much I turned it up or down. I wasnt changing the boost much, it was a case of going max 16 to max 14, and then tried going back to 17-18.
I would have though the dawes purely just sets the max boost allowance, and shouldnt affect the spool up rate etc.... But to me it seems like it did.
So in a way, what I'm asking is, do I have to re-set the needle valve, or re-adjust it, everytime I change the dawes valve ?

[Rumcajs]

I would have though the dawes purely just sets the max boost allowance, and shouldnt affect the spool up rate etc.... But to me it seems like it did.
So in a way, what I'm asking is, do I have to re-set the needle valve, or re-adjust it, everytime I change the dawes valve ?

Technically, that is correct, Dawes valve only affect max boost. However if you have set up needle valve fairly conservatively to retard the spool up rate at the expense of max boost that is; it takes longer to reach, by dropping the max boost you have now affected the performance a little.

Better approach would be to set more aggresive spool up and lower the max boost. That will keep the turbo response times better but limit max pressure which more important for the longevity.

So close the needle valve a little to recompensate. These days I only play with Dawes setting as my needle valve is almost shut.

Cheers

[Hodge]

Cheers mate. I'll have a play around tomorrow again.

[Sir Roofy]

What happened to make you fiddle with it ?
I know ,you thought you could get a bit more out
of it fine tune it a bit more lol mate once its set
leave it alone every time you touch it you faark
it up then have to start again and end up where it
was the first time,how do i know this ,i tried every
thing to improve mine a fiddle here a fiddle there
you just cant help it it hooks you your gone and
you keep at it

once set again leave it alone

[Hodge]

I wanted to back it off just a tad. Thinking that it won't throw off the spool up rate, but it did It was maybe half a turn back.
And the car is now doing it's ugly thing when I'm on 4th.
When I drop it into 4th the revs drop below the power band revs which is a 2200 memory and then the car slowly labors it's way it. Before this, it didn't do that. It would easily spool its way back up without hesitation. Weird.

Sent from my SM-G900I using Forum Runner

[BillsGU]

I wanted to back it off just a tad. Thinking that it won't throw off the spool up rate, but it did It was maybe half a turn back.
And the car is now doing it's ugly thing when I'm on 4th.
When I drop it into 4th the revs drop below the power band revs which is a 2200 memory and then the car slowly labors it's way it. Before this, it didn't do that. It would easily spool its way back up without hesitation. Weird.

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When you say "back it off" - which way did you adjust the Dawes valve? Longer or shorter (for want of better terminology)?

[Hodge]

When you say "back it off" - which way did you adjust the Dawes valve? Longer or shorter (for want of better terminology)?

Longer, I unscrewed it to drop off a psi or two.

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[Rumcajs]

Did you mark the position or created reference point before you started fiddling? I always do so I can return back to position it was if I'm unhappy with the results.

Cheers

[Hodge]

Did you mark the position or created reference point before you started fiddling? I always do so I can return back to position it was if I'm unhappy with the results.

Cheers

I did mate. But its not the same. I just went out trying to fine tune it, and getting close but no cigar. Perfect in 1st 2nd and 3rd, all the power in the world. But 4th.... Takes a while to get going...

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[Rumcajs]

Well, something doesn't compute. You have upset something else by fiddling in the engine bay. Now seeing that yours is auto could be this be related to lock up clutch on torque converter? Cause possibly in 4th it is locked and as there is no slip it bogs the engine a little. I'm speculating here as I'm not entirely familiar how CrD operates. Earlier versions would lock up converter above 80 km/h.
In any case I'd close needle valve fully and go fo run. That should give max spool up so only thing affecting boost would be Dawes valve.

Cheers

[thebrod]

I'm no expert but I'll throw my 2 cents in just for the hell of it.....
Have you tried disconnecting the battery for 20 mins to reset the ECU? Maybe that will help????

Adam

[Hodge]

@Rumcajs
Mine is a manual. And this exact same thing had happened before so I don't think I've touched anything else. Last time Mudski fine tuned it, and took it for a spin and got it spot on. He's away for work at the moment.

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[Hodge]

I'm no expert but I'll throw my 2 cents in just for the hell of it.....
Have you tried disconnecting the battery for 20 mins to reset the ECU? Maybe that will help????

Adam

Tried it mate , no change. Good call but.

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[threedogs]

Do you have a Scan-Gauge ?
I'm with RJ close the needle then set your boost again,
then only use one flat of the nut at a time to fine tune it.
Re check all fittings as RJ says you may have knocked something loose
EG a hose off the vac solenoid etc

[Hodge]

Checked and rechecked all that few times. If something was not right , I'd have issues across all gears.

My issue is once in 4th gear. Just takes forever to spool up to a decent power band. Once at the mid range, for instance at around 2700-3000,revs in 4th it has power... And I take the 3rd all the way to 3500,before changing to 4th so not like I change early or anything.

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[Sir Roofy]

mate you have to reset the dawes valve bring it back to 10 or 12 psi or 14
that's about 3 threads left on the dawes body keeping in mind all 3l motors
act differently then open your needle valve till the arm drops at the turbo
then screw it back till it lifts back up then add a tad more
see if this helps ,then get it to where you want by turning the dawes in
bit by bit very fine
and lift the right boot a bit seems a bit hard

[Rumcajs]

@Rumcajs
Mine is a manual. And this exact same thing had happened before so I don't think I've touched anything else. Last time Mudski fine tuned it, and took it for a spin and got it spot on. He's away for work at the moment.
....


Oops, the way you described the things it sounded like auto box.



Checked and rechecked all that few times. If something was not right , I'd have issues across all gears.

My issue is once in 4th gear. Just takes forever to spool up to a decent power band. Once at the mid range, for instance at around 2700-3000,revs in 4th it has power... And I take the 3rd all the way to 3500,before changing to 4th so not like I change early or anything.



Well, this really sounds like the spool up is just retarded a bit too much and the drop in RPMs when shifting to 4th causes it to back off too much. I still don't understand why only in 4th but you need to start to looking at both needle valve and Dawes valve as separate circuits. So either one taken out of the equation. So either close needle valve fully (that should give you max spool up rate or take Dawes to max boost rate. You can also just put vac line directly on the turbo actuator and observe the difference.

I wonder if the Dawes is not partially stuck open (ball not sealing up because it is full of oil)

Next time Mudski fiddles with it get involved yourself as well.

Cheers

[Hodge]

I was right there when he done it, watching him do it. And it's no different to the way I have been doing it prior and after that.... Unless there is a trick to it, I doubt it though.

Will consult with him.

[Rumcajs]

Well, you need to pull the Dawes valve apart as it seems the fiddling of yours has disrupted something and now it possibly leaks/bleeds slowly/too early. If you have means of checking for that on the bench before you gonna dismantle it, that would be great.

Cheers

[Paule]

Hodge, what is your max boost now? Does it feel like limp mode in 4th or 5th? If so back your needle valve just a bee's, not even one number

[Hodge]

Hodge, what is your max boost now? Does it feel like limp mode in 4th or 5th? If so back your needle valve just a bee's, not even one number

As she sits now, max is 16.6 or something that I got, at about 3500 revs, in 4th.
Definitely not limp mode , as I do HAVE a lot of power, up top end of 4th and 5th. If I step on it in 4th, after it spools up, to above 2500RPM, she goes like theres no tomorrow. The boost maxes out but she keeps on gaining speed no dramas.
It's the spooling up at low end thats the issue.
So here is my typical scenario.... (once car is full warm)
1st - take off rev it till 2600-3000, change to 2nd, rev till about same, 2600 - 3000, change to third...
Now out of third no matter what I rev it to, once I change to 4th, revs and boost drop and she just sits here labouring and slowly winding its way up.
As mentioned above, once up top end, power is there.

[Hodge]

Well, you need to pull the Dawes valve apart as it seems the fiddling of yours has disrupted something and now it possibly leaks/bleeds slowly/too early. If you have means of checking for that on the bench before you gonna dismantle it, that would be great.

Cheers

I'll take it all apart on weekend, or wait till mudski is back in town and free. The car is driveable no dramas, but I know it CAN be and WAS 10 times better till I (dont even know why) I decided to touch it... as I didnt think it would throw it all out of whack.

[Paule]

RJ is probably right as he is a bit of a guru, if it was me in your shoes from what you just described I would close off my needle valve more, I found with mine,which mudski also set up and I wished I never touched it cause he had it going awesome, that if I adjusted one valve it did effect the other even though it shouldn't. So if you close your needle valve off a bit your turbo should spool up quicker, the worst thing that can happen is you hit limp mode then you know you have gone that lil bit too far

[Sir Roofy]

How did you go
got it sorted did you ?

[Hodge]

I sort of got it better, but still not like it was. Will catch up with mudski when hes free. Even if 2 of us, can't get it right it's got to get a second opinion/driver, to prove it's not just me.