Overboosting!

[Graeme Shaw]

Hi all,

I have an apexi avcr fitted, and am running 1.1bar of boost.
However this time of year it is set to off, which i presume means that the solenoid is constantly open between the turbo and the actuator.
However i still over boost, hitting over 1.1 bar if i aint carefull as the revs rise.
How can this be if the pressurised air is escaping?, even before it gets to the actuator?
I do have a stage 3 hybrid turbo, but cant see how that can make any difference if all the air is escaping?

Do i need a new actuator?

Cheers Graeme

[AM TUNING]

what make turbo do u have?

i had this problem a couple off weeks ago and had to return the turbo back to the supplier , they have replace the exaust housing to a single large port rather than the smaller twin one and that has cured it,

just notesed that u have a hyper sr downpipe,

ive had lots of problems with them lately,

with 2 off them i had to remove metel and reshape it around the wategate flap area, with mine i have remade the wategate area tottaly to copy the aussie adea, ( the part that sits infront of the wategate area is now at 45degs to the other pipe, rather than 90)




andi

[gtschris.com]

what make turbo do u have?

i had this problem a couple off weeks ago and had to return the turbo back to the supplier , they have replace the exaust housing to a single large port rather than the smaller twin one and that has cured it,

just notesed that u have a hyper sr downpipe,

ive had lots of problems with them lately,

with 2 off them i had to remove metel and reshape it around the wategate flap area, with mine i have remade the wategate area tottaly to copy the aussie adea, ( the part that sits infront of the wategate area is now at 45degs to the other pipe, rather than 90)




andi

i thought the single port supra ct26 housing would not bolt up to the twin scroll design mr2 exhaust manifold.

Did you put the turbo back on or was it in a gargage?

[gtschris.com]

Hi all,

I have an apexi avcr fitted, and am running 1.1bar of boost.
However this time of year it is set to off, which i presume means that the solenoid is constantly open between the turbo and the actuator.
However i still over boost, hitting over 1.1 bar if i aint carefull as the revs rise.
How can this be if the pressurised air is escaping?, even before it gets to the actuator?
I do have a stage 3 hybrid turbo, but cant see how that can make any difference if all the air is escaping?

Do i need a new actuator?

Cheers Graeme

with your free flowing exhaust, downpipe, and the addtion of your greddy intercooler you have prob approched the limit of what the internal wastgate can flow.

i would take the avc-r solenoid off completely just to check, also you still got the t-vsv hooked up?

[AM TUNING]

the exaust housing is infact a turbotech own casting ,,, appenently they are running out off old ct26 exhaust housings units to rebuild ,,

i fitted it myself , im a tech with my own business ,,

after talking to lots of people they all came back with the same reason that the ct26 exhaust housing has beem ported and that causes boost creep,

so after a lot of bench testing and talking i asked about the single port housing , this unit is now fitted and the problem has gone,

with no boost control its running uprated actuator pressure of 10 psi, or though in very cold day it will max out at 11.5

when u look inside the exaust housing it enters as twin entry and then just flows to one with one large wastgate flap

[jonno]

Hi all,

I have an apexi avcr fitted, and am running 1.1bar of boost.
However this time of year it is set to off, which i presume means that the solenoid is constantly open between the turbo and the actuator.
However i still over boost, hitting over 1.1 bar if i aint carefull as the revs rise.
How can this be if the pressurised air is escaping?, even before it gets to the actuator?
I do have a stage 3 hybrid turbo, but cant see how that can make any difference if all the air is escaping?

Do i need a new actuator?

Cheers Graeme

The HyperSR downpipe is a rubbish design and will cause boost creep - there isnt enough space behind the wastegate to vent enough exhaust gas and so some still runs through the turbo even when the gate is open. Get an Aussie or similar instead, or even put the stock turbo elbow back on!.

[Graeme Shaw]

Chris

I think the tvis is still enabled im not sure what this is?!

Graeme

[The Morris]

The HyperSR downpipe is a rubbish design and will cause boost creep - there isnt enough space behind the wastegate to vent enough exhaust gas and so some still runs through the turbo even when the gate is open. Get an Aussie or similar instead, or even put the stock turbo elbow back on!.[/quote]

hi im glad you think the hyper SR is a load of crap,if you look on my overboosting thread under mechanical you will see im having problems and i hope its the hyper sr downpipe, although they say they have never had a problem. The service from them is shocking. Ive waited over 3 weeks for a refund.

[AM TUNING]

after my experience and THE MORRIS car too , i would say its related to downpipe,

synce remaking my downpipe around the wategate area my overboosting problems have gone away,

[Graeme Shaw]

Ok

Who can offer me an Aussie downpipe!?

Graeme

[gtschris.com]

Ok

Who can offer me an Aussie downpipe!?

Graeme

Me

well there not Aussie but just as nice quailty in 3" 304 stainless. get me on the normal email or pop around and we'll can look at your car first.

[MR2Mania]

Hi all,

I have an apexi avcr fitted, and am running 1.1bar of boost.
However this time of year it is set to off, which i presume means that the solenoid is constantly open between the turbo and the actuator.
However i still over boost, hitting over 1.1 bar if i aint carefull as the revs rise.
How can this be if the pressurised air is escaping?, even before it gets to the actuator?
I do have a stage 3 hybrid turbo, but cant see how that can make any difference if all the air is escaping?

Do i need a new actuator?

Cheers Graeme

Graeme,

As Chris says, take the AVCR's solenoid out of the loop. An easy way to do this is get a vacuum hose and connect it from the turbo's compressor cover to the actuator directly. With it like this, you should only boost to the level set by the actuator. Hybrid turbos may boost higher though at high RPM. A downpipe that doesn't allow the wastegate to fully open will also cause overboost, and it would seem that this is what the HSR one suffers from.

Does your actuator have 1 or 2 ports? If you've got 2 ports, this is like the standard one, and what you'd need to do is block one of them up (fit a short vacuum hose to it, with something like a bolt in one end to block it off). This is the one that would otherwise go to the VSV (the VSV is the solenoid used by the standard ECU to control boost - you need to disable this when running an aftermarket boost controller such as the AVCR. Blocking one of the actuator ports will do this).

As you look at the actuator from the passenger side of the car, the right hand port of the actuator (if it has 2 ports) is the one that would go to the VSV.

[Graeme Shaw]

Ah

Yes have already blocked off the said port. Is that all i need to do or do i need to dissconect it electrically also?
So is that the t-vsv?

Cheers Graeme

[MR2Mania]

Ah

Yes have already blocked off the said port. Is that all i need to do or do i need to dissconect it electrically also?
So is that the t-vsv?

Cheers Graeme

Nope, you don't need to unplug it. That's it, it no longer has an effect on boost. (I'm not sure if the ECU would be happy if you unplugged it, anyway?).

Yes, it is what is referred to as the T-VSV.

Good luck, hope you find what's causing the overboost.

[Graeme Shaw]

Ok Thanks mate!

Can i just ask what the Tvis is then?

I read of a lot of people gutting them?

Graeme

[MR2Mania]

Ok Thanks mate!

Can i just ask what the Tvis is then?

I read of a lot of people gutting them?

Graeme

The TVIS is a set of flaps in a plate that sits between inlet manifold and the cylinder head. It's only on the Rev1/2. Basically, the ECU (via vacuum control) opens and closes the flaps to increase/decrease the size of the ports. When the engine is at lower revs the flaps are shut, limiting the size of the port. At a certain RPM point the flaps open to increase the port size.

The reason for the TVIS is supposedly to keep the airflow at a reasonably fast speed when at low Revs - basically, to give bit better torque low down. It was ditched for the rev3 though.