testing a faulty actuator boost problems gt28rs

ive been having some problems with boost control on my coop and ive been advised this and that by various people and ive tried them all with no progress.

no i was told by a mate yesterday to test all the pipes again and try the actuator. when i asked how he said to pump air into it with a foot pump or compressor and it should read 0.8 bar as that is what the actuator is rated at.

now i got hold of my trusty 12v compressor and pumped air in, first of all i got a hissing noise from the pipe so i changed it and secured it to the actuator with a hose clip, hoping this would cure the problem. it didnt!

i then pumped in more air to the actuator with the pipe secured. no hissing was heard. the arm was moving but only a 65'(approx) swing no a full 90'. dont know if that makes a difference.

the read i was getting on my pump was 40 psi which is over 2 bar! which to my understanding the actuator is knackered.

or is it. any one able to help me further with this as now the car is on the road andim using it all the time its doing my head in as noithing will contoll the boost at all and it runs 1.35 bar all the time doesent matter what setting the greddy is on or what a prv is set at!

have you tried connecting the compressor housing pipe straight to the actuator? bypassing any boost control valves / solenoids completely. thats the best way to test your actuator, see what base boost you are getting.

thats the way its running now! still the same!

Just been told by the supplier of the turbo that the actuator should have a preset to 1.0bar so i cant go less than that. so if i fiddle around with the actuator i should get lower std boost and then the greddy should work!

true or not??

There seem to be a few of us with boost control problems, me included and both myself and goose (maybe some others?) are using Greddy to control it. Mine seems to have worked well for a while - now I cant control boost with it at all - do we need to look at the valve unit/replace it?

Just a thought, what do you all think?

I had boost control problems related to the greddy. I have ran these past goose and we believe it not to be the greddy. If its running 1.35 bar all the time, then it sounds like something is jammed. Is there no feeds going to the greddy then?

Ross

does it spool up normally then level out or spool up slowly and peak then drop off again?

if the wastegate was stuck half open then it would spool up more slowly and peak at 1.35 before starting to tail off again.

if it gets to 1.35 at normal spool up speed and holds it steady there then the wastegate wont be stuck. in this scenario it sounds like the actuator to me.

With mine it was boosting up to 1.32, spooling up nice and quick and aggressively - the car was flying - then out of nowhere it was overboosting - ive tried all sorts of settings with the greddy but just cant get it to control the boost.

Before this I could floor it and the boost was controlled, now if I floor it it will overboost to 1.68 etc... (obviously I dont do that)but it develops massive boost and doesnt transfer it. The massive overboost is worrying. Even if I allow it to make 1.1/1.3 bar it just doesnt seem to transfer it.

Mark, your wastegate isnt opening fully, thats what causes it to wildly overboost.

The wastegate could be getting stuck when it reaches a certain point, or it could be the actuator needs adjusting or replacing. In both cases, the greddy wont be able to do anything about it.

First thing I would do is bypass the Greddy completely just to be sure thats not causing it. Connect the hose from the compressor housing straight to the hose from the actuator, and that will give you base boost. if your base boost is normal (0.5 bar (normal) to 0.7 bar (uprated actuator)) then the greddy is the cause. if its still overboosting then the problem is the wastegate or the actuator.

well i adjusted the actuator as per the suppliers request. now its dropped the target base boost to 0.9 bar but it still shoots up to 1.35 bar at around 4.5k.

he thinks its a possibilty the diaphram is damaged in the actuator, so i have one more test to do on it now to tell if it is knackered or not.

he did mention that its a possibility of a bad match to the car. i.e turbo too big or small for the engine and stage of tune! could that be a possibility?? i cant see it myself.

and aside from the greddy (which is crap) its running base boost a simple pipe at the moment.

the greddy is getting binned and im going for an apexi avcr!

There is nothing wrong with the greddy, and the turbo is not too big or too small for the engine. Sounds like the wastegate is not opening properly, thats what causes the boost to shoot up. possibly due to the actuator, or it could just be getting stuck somehow. I dont know if its possible to change the actuator without taking the turbo off?

Why bin the greddy when clearly its not the cause?

Ross

I'll have it.... ?

sorry haven't read the whole thread but it is supposed to move open with the preset - it is not supposed to leak, so if you have pumped it up to 2 bar it should be as open as it can get but it will not discharge it down to your preset boost - that's not how it works. How open it gets is open to the design but it should be pretty open.

so how do i test it then properly to see if there is a fault.

ive been told to use a foot pump and pump it up and see if it hold air with the arm out if it looses air then is a diaphram leak!

correct????

i fancy an apexi hence the change, my trust in greddy has seriously been dented after the problems ive had with them. even when i put it on the car when i was standard it wasnt right!

The simplest test to know if something is wrong is plumb the compressor cover into the actuator directly with a brand new piece of pipe. If you get too much boost you can assume the actuator is faulty or the gate on the turbo itself is jammed.

The footpump tests for one fault but a footpump won't work and whoever suggested that is an idiot as 9 out of 10 of them leak slightly. The professionals have a hand pump they use. IF the wastegate is opening some then it probably isn't the actuator unless it is adjusted massively incorrectly

im running it that way at the mo john.

last night i adjusted the actuator to run less boost but ended up lowereing the target boost but the creep was up to 1.4 bar!

and the pipe used to connect the actuator to the compressor is brand new!

I might have a new spare actuator I can send you to try as an alternative. But not back at home until Monday to look tho. If you disconnect the actuator arm can you easily open the gate fully by hand?

no, the rod is pretty stiff, and its still mounted on the car and space is limited. i had to force it over the wastegate bracket with a pair of pliers!

is the actuator that you have off an rs?

if you could send it to me that would be great mate just so i can try it up, that way i can make a warranty claim then for the duff actuator. its what im putting my money on anyway!

Deplumbed the greddy valve today.

Plumbed the compressor to the actuator, the resultant boost is 0.55. Just less than 0.7 when pushed.

Greddy valve?

What was happening before?

Ross

Ross...


With mine it was boosting up to 1.32, spooling up nice and quick and aggressively - the car was flying - then out of nowhere it was overboosting - ive tried all sorts of settings with the greddy but just cant get it to control the boost.

Before this I could floor it and the boost was controlled, now if I floor it it will overboost to 1.68 etc... (obviously I dont do that)but it develops massive boost and doesnt transfer it. The massive overboost is worrying. Even if I allow it to make 1.1/1.3 bar it just doesnt seem to transfer it.

What do you think?

With the valve diverted and running on base, I can feel the turbo come in as it should and respond as it should on base boost. With the Greddy in place it would show boost building with very little throttle or acceleration, overboost massively and without the expected acceleration etc... Both the Greddy and manual guage showing the overboost.

new actuator came!

fitted!

no joy!

still does the same.

i need help people as there is a box of matches and a sledge hammer staring at me and im thinking of putting them to use!

with the actuator disconnected from the wastegate, can you freely open the wastegate all the way by hand?

a full 90 degrees? yes!

is it true that the actuator adjustment must be half an eye and pulled over the wastegate?

it should freely open all the way, to 90 degrees or whatever it is.

yes half an eye back of the peg is what barbz told me.

right its wound inwards to half an eye of the peg and it opens a full 90degrees with no restictions.

ive just added a prv to see and it ran 0.1 bar more and that was at its lowest setting. and ive replaced all the piping coming from the actuator to the compresor.

if it was leaking boost else where surely it would back off boost not increase boost?

what else can i check?

It 'could' be your setup is too free flowing and the wastgate
cant release/flow enough of the exhaust gasses away
Hence the boost rising with the rpm

Just a theaory

Ben

so what would be a way of stopping that?

the down pipe is 2 and half into 3 inch in order to get the bend right!

me and you have simular specs benny so its got to be something silly! as yours works! lol

well... you could TEST it, by removing the wastegate completely, or forcing it to be open all the time. If it still did it then you've found the problem, I doubt it would be that though.

as part of a test i took the actuator arm off and left the wastegate closed (freely)and i had little or no boost up until 5.5-6k rpm then i had about 1.0bar!

if thats any relavence!?

Can you recap all the things you have tried and replaced?

yeah nearly all the boost signal pipes
the actuator
intercooler pipes
ran with and without different dumpvalves
taken actuator arm off
ran with pipes off
changed boost controllers
tried a prv
tried base boost set up


benny came down and had a look at it today


he seems to think that the system is too flowing and that not enough gasses are being realesed. might need an external wastegate or a ported internal wastegate!

anything you can help on there flea?

Ive tried most of the things you listed aswell Goose,Im out of ideas now Its probably something really stupid