Overboosting

[skiddusmarkus]

Since I had the rest of my exhaust made in 3" pipe, the gt3071 has spooled much faster even on part throttle.My problem is now I've done a fair few miles on it, its overboosting.The new forge actuator is set at 1.2 bar and I am sure it opened at this on the old mongoose but now the boost shoots up to nearly 2 bar very very quickly so I just have to lift off.
I have a greddy e-01 boost controller which i had just set to off until it is mapped but tried turning it onto low and then setting everything to 0% which would just be the same as it being off but allows me to use the warning function on it which will reduce boost by a % when it hits the level you want.I set this at 1.2 bar with a reduction of 15% and although the warning light and buzzer came on when it hit(and passed) this, it didn't drop open the actuator and reduce the boost.
Now maybe its just a massive spike and it would drop on its own but I am not prepared to hold the throttle in long enough to find out until its mapped.

Things I think it could be are:

Split vacuum hose off the actuator-unlikely as its pretty new silicone hose.

Forge actuator not working.

Thoughts please?

 

[Tim]

Whoops, I must have rubbed some of my overboosting vibes onto your car..

 

[campbellju]

Is the Greddy reading the boost correctly? Just trying to eliminate a control issue. Failing that then you are on the right lines with leaking hose/joint.

Can you quickly just run one hose from the inlet manifold to the actuator to eliminate the control side of the boost controller ?

 

[skiddusmarkus]

I'll see if I've got a peice of hose long enough to try that, thanks.Its always read the boost fine before and until the exhaust was swapped it wouldn't go over 1.19 bar.

Yeah Tim, you gave my car the lurgy.

 

[geoff pine]

I'm confused i thought that if its a1.2 bar actuator that was the lowest boost it would run :doh:

 

[skiddusmarkus]

Its when the actuator opens, can be held shut for more boost with a controller.You're sort of right that it is the lowest boost it will run when its at full boost though(with no controller).

 

[stumo]

Check for leaks in the system.

Remove the shitty boost controller from the system and see what happens. Pipe the actuator properly.

If it cures the problem then you know the shitty boost controller really is shitty as a shitty thing. Get a proper boost controller,ie, none of that Jap shit with percentages and gain and other shitty adjustments.

If it doesn't cure it then either the place where you're taking boost from is a poor place to take it from or possibly the hose might have a restriction in it or the actuator might be a bit sticky (probibly from you wa#king over the shitty boost controller).

The problem with most boost controllers and modern roller turbos that spool up quick is they don't react fast enough.
That's where the "gain" adjustment comes in, what that does is as the turbo is coming up to the boost level required (which is a guestimate of a percentage of the original boost ....who the feck makes this stuff up) it makes the boost trail off so that you get a smooth transition to the boost level.
What that means in reality is the turbo isn't able to be as good as it can be.

 

[Mad]

I have that very boost controller and it was doing the same thing on my Fiat Coupe so I fitted a bleed valve or manual boost controller instead of the Greedy and problem sorted.

I would not recommend a bleed valve but it may help to find out where your problem lies. The alternative is not run a bleed valve and instead run a direct hose, running on actuator boost.

With regards to Boost Controllers, its a matter of opinion but the plus / minus settings are very good for controlling your boost in different gears and the Apexi AVC-R is probably the best one to have. If your car is pulling higher or lower boost in certain gears, its a lot easier to adjust the AVC-R than go and have the car remapped.

 

[skiddusmarkus]

Check for leaks in the system.

Remove the shitty boost controller from the system and see what happens. Pipe the actuator properly.

If it cures the problem then you know the shitty boost controller really is shitty as a shitty thing. Get a proper boost controller,ie, none of that Jap shit with percentages and gain and other shitty adjustments.

If it doesn't cure it then either the place where you're taking boost from is a poor place to take it from or possibly the hose might have a restriction in it or the actuator might be a bit sticky (probibly from you wa#king over the shitty boost controller).

The problem with most boost controllers and modern roller turbos that spool up quick is they don't react fast enough.
That's where the "gain" adjustment comes in, what that does is as the turbo is coming up to the boost level required (which is a guestimate of a percentage of the original boost ....who the feck makes this stuff up) it makes the boost trail off so that you get a smooth transition to the boost level.
What that means in reality is the turbo isn't able to be as good as it can be.

I think the "gain" on this controller is to increase boost as it starts to tail off as you can increase it in rpm increments if you want and the "set" is to keep the wastegate closed longer to help initial spool.You're right though, it is overly complicated and could be much simpler.
Will try running a pipe straight from actuator to under inlet mani tomorrow but I think that being used already for the fpr, I can't remember.

When I set the forge actuator I just adjusted it until it was nice and tight at rest with no rattles on the penny.I might have maybe been able to get another half turn on the rod thread but it seemed a good seal to me already and I didn't want to be pushing the rod back into the actuator if you know what I mean.

 

[ashills]

where do u take the boost source from best place is straight after the pipe leaves the turbo before the intercooler

but first thing stick a long length of hose on like stumo says will tell you alot straight away

 

[stumo]

When I set the forge actuator I just adjusted it until it was nice and tight at rest with no rattles on the penny

you need some tension on the arm/actuator, they are usually adjusted so that the hole is halfway past the post on the arm.

If there isn't enough tension the boost won't be controlled enough as there isn't enough spring pressure.

That sounds like it's your problem and it's been made worse by the 3inch zorst allowing the turbo to spool up a lot quicker too.

I would still pipe up the actuator (after adjusting the rod) bypassing the boost controller and see what happens.

 

[skiddusmarkus]

I've just tried it with the vacuum pipe going dierct from the actuator to the bit under the entrance to the inlet manifold and it was no different.

 

[skiddusmarkus]

you need some tension on the arm/actuator, they are usually adjusted so that the hole is halfway past the post on the arm.

If there isn't enough tension the boost won't be controlled enough as there isn't enough spring pressure.

That sounds like it's your problem and it's been made worse by the 3inch zorst allowing the turbo to spool up a lot quicker too.

I would still pipe up the actuator (after adjusting the rod) bypassing the boost controller and see what happens.

I think you are right, was just hoping it wasn't going to be this.Is it possible to adjust the actuator rod in situ or has the turbo got to come off again?Does the rod travel inside the actuator as it opens the wastegate as if it does then it might be possible to undo the 2 nuts that hold it onto the bracket and then pull it out enough to unscrew it-I guess then the problem is if you tighten it up even more then it will be too hard to get back onto the bracket, unless maybe the bracket could have 2 slits cut in it that meets the holes to allow the actuator to slide into the bracket then be secured with the nuts.

 

[stumo]

haha you lost me there.....

If you have the hole 1/2 way over the stud you will have to pull the rod out of the actuator to put it on the wastegate stud.

on the end of the rod that comes out the actuator, there should be adjustment (undo the nut and the end should turn on the thread)

If you're using a std manifold then space is gonna be tight

 

[stumo]

as you can see, there's adjustment on the end of the rod.

From what you've said you will need to "shorten" the rod so you have more tension on the spring.

 

[stumo]

this is how you want it to look....it's not my drawing...mine would be much worse

 

[skiddusmarkus]

Yeah I already chopped half and inch or so off the end of the rod as it was too long.It was probably a 1/4 of the hole on the end of the rod too short so the wastegate flapper arm was tight when I put the end of the rod over it.
What I don't understand is, surely the wastegate wants to open all the time as it being pushed against by the exhaust gases.If its staying shut and not controlling the boost then wouldn't that mean if anything it was too tight than too loose?

Edit:I did it how you show in the diagram

 

[stumo]

The boost is controlled by the spring.

the boost pressure presses on the diaphragm, when the pressure against the diaphragm is greater than the spring pressure (that's on the other side of the diaphragm) the actuator rod gets pushed out and opens the wastegate. The opening wastegate lowers the pressure inside the turbine housing and the turbo slows down, that causes the boost to drop.

If the boost pressure drops too much then the spring overcomes the boost and the wastegate will close, allowing the turbo to spin faster as the exhaust gasses aren't bypassing the turbine .

in effect it has nothing to do with the wastegate (it does but not at this simplistic level)

 

[skiddusmarkus]

Ok, I think I understand now.So it probably needs another turn or 2 on the thread to get some more tension on the spring to make it work properly then.Ah well, off comes the turbo again I guess.

 

[skiddusmarkus]

where do u take the boost source from best place is straight after the pipe leaves the turbo before the intercooler

but first thing stick a long length of hose on like stumo says will tell you alot straight away

What are those little vacuum t off pipes called that the yanks usually have on the turbo outlet?I could fit on of them onto a stainless coupler I have between the turbo and the main intercooler pipe run.