Boost Creep

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pulsarboby

Guest
as above ross, could be that the rod is pulled over too far and not opening the wastegate far enough.
as carl says it should be pulled over by no more than half the hole on the peg

thats the only thing i can possibly think of other than a longshot that there maybe a blockage in your exhaust system which could back up pressure on boost, but then you would find the car would be down on power even though turbo is boosting
 
wrc

wrc

Member
Cheers Bob, Carl

Definatly not a blocked exhaust, its about as free flowing as you can get (front exit lol)


How do you mean by "it should be pulled over by no more than half the hole on the peg" - i thought the adjustment on the rod was in the thread?
 
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pulsarboby

Guest
yes it is on the thread but you have a round hole in end of adjustment rod which fits over the peg to operate the opening and closing of the wastegate.
you need to adjust the rod lengh so you have to physically pull the arm over the peg by half the width of the hole.....sorry but hard to explain lol
if its pulled over too far then the actuator may have trouble opening the wastegate penny
 
wrc

wrc

Member
Cheers for the pic, legend.

Did some more investigating and tinkering last night, even with the pressure source linked direct with the actuator I'm still hitting a bar, it wants to stay at 0.5 bar but just gets over powered and before you know it, back to a bar and rising.

Put a basic small tyre inflator on the actuator hose and it's fully opening and closing. Closed at 0 psi and fully open at just under 14-15 psi. About correct would you say?


It must be too much pre load on the Wastegate? It's literally the only thing I can think of now, weird thing is bob that I didn't adjust it before fitting and that actuator came off that turbo so I almost disregarded that but I'm now at my wits end.


Just got to pluck up the courage to get adjusting the actuator, I'm not looking forward to doing it in situ at ALL lol
 
wrc

wrc

Member
The thought hadn't really crossed my mind, as it was holding boost absolutely fine before I changed to a very good 360 degree thrust stock turbo. Although thinking about it the old turbo came off with 5 (yes 5) large cracks around the Wastegate...

Hmmmm....
 
PobodY

PobodY

Moderators
Staff member
Did the "new" turbo come with an actuator on it, or did you swap them over? - Is it a Forge 1bar actuator by any chance?
If you swapped them, then the chances are that it's just got too much pre-load on it.
 
wrc

wrc

Member
The actuator and turbo are from the same car, but have been separated and refitted. It's no forge item but a very good condition stock unit which I'm sure has a stronger spring fitted when the turbo had work. On the invoice for the turbo it states (actuator replaced and set to 1 bar)....

Not looking forward to going back there and adjusting it :( lol
 
PobodY

PobodY

Moderators
Staff member
I'm pretty sure you can't adjust the spring pressure in the standard actuator (or there'd be no reason to buy the "uprated" ones); it's crimped shut around the edges where the adjustable ones will have a series of small screws.
Obviously that doesn't explain your creep, but it does suggest it should be holding 1bar rather than 0.5.
 
wrc

wrc

Member
Oh if only it would actually hold 1 bar, rather than hitting
a bar and then keep on going!

As discussed, has to be to much pre load. Would make sense as essentially the Dawes is ttrying to do its job but must be so much pre load on the actuator iit's just pulling the Wastegate sstraight back closed.
 
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skiddusmarkus

Active Member
If the old turbo had so many cracks, maybe it was leaking a lot of exhaust gas pass the wastegate already and had to spin faster to get the same result and the preload was adjusted accordingly.Now with a turbo with no leaks its too much?

I had a similar problem but it turned out to be a ripped diaphragm in the actuator and the turbo had to come off to change it(not standard fitting).
 
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pulsarboby

Guest
yeah that actuator although it looks stock i would have aid has a 1 bar spring fitted as its harder to pull open than others weve had, if you tested it at 14-15psi thats also confirming that.
as said if it does have too much preload it could possibly cause a prob with boost creep because if you are running direct from plenum to actuator then youve bypassed any other possible faults really
 
wrc

wrc

Member
Well after this mornings posts I had to get cracking and try and adjust the actuator otherwise it would have bothered me all week lol

Actuator rod popped off the Wastegate pin...... It flys back and reveals a good 10-12mm gap between the hole and pin LOL. After some debating I was defiantly not adjusting it in situ and couldn't get to the rear most 11mm nut so I manipulated the bracket slightly to bring her more in line. Got her as right as I could, then spent 2 hours getting the circlip back on the end of the actuator rod (I swear I was going to do myself in if it took and longer lol)

And then.... Up the road we go, get her warmed up...... Duel carriage way here we come..... Holds 1.1 bar like a beauty ;)

My god I was so happy lmao


So you were right all along, thank you SO much for all you guys help, I'd never of guessed.


The only concern I have is that in 4th gear it wants to hold 1.2/1.3 but thats something that can be sorted with a map next month so doesn't bother me 'too' much.

Love you all long time x
 
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pulsarboby

Guest
cool glad its sorted ross:thumbsup:
its the only thing it could possibly have been, if you want it a little closer rather than adjusting the rod etc....fit a couple of thin spacer washers between the bracket and actuator then bolt it up, a little awquard to do but saves the agg of taking it all off
 
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