Grande Punto Grande punto t jet turbo actuator

[Adamvickerstjet]

Hi guys I have currently brought a punto t jet the mods are abarth vl36 turbo an induction and a powerflow exhaust system with a map and it's currently running 191bhp but I want it to hold boost for longer and I've heard that the forge actuater is a good idea with the yellow spring but wanted a bit of info first about weather I will need a new map or any other things are needed and what's the procedure ??

 

[alextjet120]

didi you get an answer on this bud, same question :bang:

 

[Bernievarian]

Any modification (improvment ?) on the air system should be reported to the ECU in order to bring some benefit. Say the boost pressure goes higher with the new Forge actuator and whatever color spring, if the boost pressure threshold ir reached the ECU will go in limp mode... So it's a yes, You need to remap it unless you like to throw your money away !

Regards, Bernie

 

[aurick86]

I don't believe the problem is with the actuator.

Because there is electronic boost control and because the car does keep higher boost for a few seconds.

It's either the physical limitations of the turbo .. or more likely a combination of turbo size limitations and the ECU is set up to not over spin the turbo at high engine rpm.. so that the both the engine and turbo last longer.

A turbo can always spin faster.. but it will not make anymore power once it gets out of the efficiency range ...because of a combination of heat and other things i do not fully understand.

I say this because boost is electronically controlled:
-the actuator sees no pressure until the ecu wants to actuate the N75 valve
-ECU controls the N75 valve through PWM
-it's a closed loop
-ecu will always try to reach the wanted boost....it will increase/decrease the PWM => more/less boost to the actuator.
-a spring that is to stiff will probably cause the ECU to throw an error... because it cannot get the boost low enough at a certain RPM.

Having said that... there has to be a spring that will increase the top end boost without getting the ECU to freak out.

 

[Bernievarian]

Unless you get the ECU's boost / torque maps edited the right way, it will limit the boost pressure to the old maps values, and throw the boost error / go in limp mode if the preset safety threshold is reached, spring or not ...

Regards, Bernie

 

[Little Boy]

He already has remapped ECU... so ???
I will go for yes, different actuator / spring can bring you some boost:
1) there is some pressure difference/drop on turbine, this pressure forces waste-gate to open even if ECU wants waste-gate to be closed. Actuator spring has to be strong enough to hold this pressure. This pressure will rise with power output of engine.
2) PWM signal for control valve seems to follow some internal ECU model more then closed control loop, so it is very optimistic to thinks that boost follows what ECU wants. Tuned ECU behavior is more like 'give me everything you can'. Mine PWM signal goes to 'close' waste-gate position with rising RPMs and boost dropping fast anyway. So weak actuator could be the case.

 

[Bernievarian]

Hi, if His ECU is like "gi' me all ya can" I'd agree, possibly some more boost, until it reaches the safety limit, then: limp mode, where is the gain ?
Look at the actuator circuit on a T-Jet: high pressure from turbo outlet goes to the actuator THROUGH a PWM ECU controlled 3 way valve, if the ECU says the wastegate to stay closed it will, not matter the spring ! BUT, if it says open WG and the spring it TOO strong, WG won't open, pressure will increase further, give a kick in the back (cool but that's becoming a dangerous uncontrolled regulation !
You can try to pinch the high pressure tube going to the EV, the actuator won't open the WG ; IF you feel more boost (yo will more probably !), then you could start to "feel" when it's time to release your foot before the ECU does it for you en enters limp mode...

Regards, Bernie

 

[aurick86]

He already has remapped ECU... so ???
I will go for yes, different actuator / spring can bring you some boost:
1) there is some pressure difference/drop on turbine, this pressure forces waste-gate to open even if ECU wants waste-gate to be closed. Actuator spring has to be strong enough to hold this pressure. This pressure will rise with power output of engine.
2) PWM signal for control valve seems to follow some internal ECU model more then closed control loop, so it is very optimistic to thinks that boost follows what ECU wants. Tuned ECU behavior is more like 'give me everything you can'. Mine PWM signal goes to 'close' waste-gate position with rising RPMs and boost dropping fast anyway. So weak actuator could be the case.

It's quite simple to see if it's the ECU or turbo/actuator that drops the pressure:
MES=>graph of intake pressure, rpm, boostvalve signal(%)

When i said "closed loop" i did not explain:
-the ecu expects a certain boost at certain rpm/load...
-it will use the n75 boost valve and MAP/boost sensor to get as close as it can to the boost values it expects.
- If for some reason the boost is not within an acceptable limit , the ECU will consider something is faulty..and will eventually throw a code.

On the vl36 turbo the waste gate is quite small and if you just remove the hose going to the actuator, i am sure the waste-gate will stay closed, if the only thing pushing it open is the pressure in the turbo.

In fact i have a vl36 turbo at home.. i could try some weights to see when it opens (easily convert that to psi).. problem is i don't have any weights, scale.. even empty bottles ... recently moved ... don't have a lot of my old stuf.
A pull/hanging scale would be nice

 

[alextjet120]

So I have the vl36 and I'm installing a bluespark which should be here tommorow (one of you may of helped on my own thread I'm not sure) or Friday, which I believe plugs into some of the map and other sensors mentioned. I'm also going to install a bleed valve to gain a few psi, I'll do a few runs to find the limp mode limit.
My question is on the diagram posted, how do I install the bleed valve correctly ( I already have a boost gauge if that makes any difference) cheers fellas

 

[Bernievarian]

@ Auricks: the WG will open IF the turbo pressure is high enough AND the actuator valve is driven by the ECU, otherwise it stays closed...
@ Alex: bleed valve should be installed as a derivation AFTER the actuator valve as when the valve will ask (prompted by the ECU) to open the WG, the valve will not respond to small opening instruction (PWM) due to the extra valve bleeding, thus allowing more boost... Once again, untill the limp mode threshold is reached (unless remapped)...

Regards, Bernie

 

[aurick86]

@ Auricks: the WG will open IF the turbo pressure is high enough AND the actuator valve is driven by the ECU, otherwise it stays closed...

I know... that is why i say that a stiffer spring will do nothing.... ok it will .. if the spring is strong enough.. but at that time the ecu should have already thrown an error.

 

[alextjet120]

thanks for helping bernie i just dont quite understand,
there is a vacum hose from the actuator, to what im guessing is the factory boost control valve plugged in, a small hose to the induction piping, and one to the bottom of the turbo.
do i put the bleed valve between the two circled red, and then what do i do with the other hose and the sensor plugged in? cheers

 

[Bernievarian]

Hi Alex, let me explain how it works first:

- as the turbo starts getting speed the output pressure increases in the intake pipe so does it BEFORE the Electro-Valve which is closed at this time
- when the pressure reaches a preset value, the ECU opens the 3 way valve which opens the communication between high pressure side and actuator: the actuator moves and opens the wastegate -> turbospeed decreases so do the ouptut pressure = regulation
- When the pressure decreases, the ECU closes the 3 way valve which close the high pressure side to the actuator and open communication from actuator to turbo inlet (low pressure) the internal spring push back the actuator: the waastegate closes = regulation

Of course this is not exactly that way, the open/close signal is a PWM (pulse width modulation) which result in a smooth motion of the actuator / wastegate (not on / off)
The idea of the additional bleed valve is to create a leak AFTER the actuator so the pressure effect when the 3 way valve opens will be offset a bit, resulting in more boost pressure before the wastegate opens.

Nice, BUT, the ECU will see this increase in pressure and will ask stronger the 3 way valve to open = regulation anyway (but maybe a little longer boost...) AND if the bleed (leak) is too big, the wastegate won't open fully, pressure will keep increasing and will reach the 'limp mode' threshold = you're stuck @ 3000 rpm ;-)

Regards, Bernie

 

[alextjet120]

I see, to install before the electro valve would I have to bypass it down to the turbo straight through the bleed valve?

 

[Bernievarian]

If you install the bleeder BEFORE the valve, you will have a permanent leak that could be noisy and annoying on the long term. If the bleed valve has only one port, install a 'T' piece AFTER the 3 way valve and connect the bleed valve to it. Then adjust the bleeder (trial and error) to reach the extra boost you aim without triggering the limp mode...

Regards, Bernie