burbling1

iTrader: (1)

Right then been having a boost issue since I bought my 94 wagon 2 years ago. I have since changed the turbo to td05 changed the ecu to a chipped z4 and put a full decat exhaust on it.

I have recently changed all the small boost hoses from turbo to solinoid and back to the actuator, changed the solinoid itself and the map sensor but Im still getting overboost. Im currently running it on what I think is just the actuator pressure whuch means I dont really get full boost until Im in 4th or 5th gear and boost build srrms slow as it the turbo starts coming in at about 2500rpm but doesnt rech full boost until about 5000rpm.

Where do you think my problem coukd be?

Is there an accurate way of testing the actuator or could my problem be elsewere.

Thanks.

Glowplug

iTrader: (8)

Need a few more details mate,
do you have a boost gauge fitted,(if not get one fitted)
if so, whats it reading?
what chip do you have fitted?

Full boost will only be reached in 4/5th.

To test the wastegate actuator just loop a pipe from the turbo nipple to the actuator, should show 0.5 bar.

Also if you have a large bore up pipe then that will slow the spool up time.

burbling1

iTrader: (1)

Yes have a boost gauge reeds 16 psi when on full boost in top gear.
The chip is a 1.1bar imortal performance on. this is the second chip and 3rd ecu so dont think thats the problem.
Standard up pipe.
If I have lots of tension on the actuator will this not make an effect on the 0.5 bar of pressure?
What boost should i get in other gears?
Edit. How do I correctly set the actuator?

Glowplug

iTrader: (8)

I to have a chipped ecu (polarperformance) running 1.1 bar and hit 16psi at WOT in 5th.

If you have an adjustable wastegate then yes more tension will have an effect on the operating pressure, but if your hitting 16psi in top then, firstly you are not running at actuator pressure and secondly you are not exeeding 1.1bar and therefore should not be getting 'cut'.

If you dissconnect the actuator arm and adjust it so that you cant quite get the pin back in without pulling the arm, then that is about right

burbling1

iTrader: (1)

The only reason its only hitting 16 psi is cos I have adjusted the actuator arm. Before it was going way past this but this may be due to the arm being to tight. I think it the moment I have to pull it about 3mm to go onto the pin so will adjust thus to less than 2mm. I thought that I should of been hitting 16psi in 2nd 3rd 4th and 5th but obviosly not.
So all the overboosting I have been getting in the past could be down to the arm being to tight but it was as tight as a nuns chuff when I bought the turbo so thought that the problem was elsewere on the car.
I was thinking the actuator wasnt tight enough and it was just the boost pressure that was opening the wastegate as apposed to the actuator hence not having full boost in all gears and slow spool time.
Roughly what pressure should the wastegate start to open without the actuator opening it.
Also what revs do you get your 16psi at.

Glowplug

iTrader: (8)

Yeah attach the arm so there is 'just' no play.


Wastegate operating pressure is around 0.5 bar or 7psi.


Dno what my rpm is at 16psi, prob take a run out tomorrow and let you know

burbling1

iTrader: (1)

Thanks for your replies fella, I will have a play tomorrow and hopefully that will be the end of it.

scoobaru mad

iTrader: (2)

did you sort it??? im having the same problem? only ive changed the turbo, all the piping to samco 3 times, fitted a front mount, changed the ecu twice, 3 actuators, an apexi avc-r NOTHING will stop it overboosting????? i love me car to bits. but im gonna have to part ex it other wise?

Glowplug

iTrader: (8)

What psi/bar are you hitting cut at???

burbling1

iTrader: (1)

Ok so I slackened the actuator right off so I only had to pull it a tiny bit to hook onto the pin been for a drive and only reaches 10psi max.I have now tightened it back up and is hitting 15psi.

Whats the benifits of an electronic boost controller? Will I be able to hit 16psi in all gears without the worry of overboosting in top gear?

Just another one while am thinking is there a way of bleeding boost off from the map sensor so when in top gear if it does go to 17 or 18psi it doesnt hit the fuel cut?

Glowplug

iTrader: (8)

Have you got the boost control solenoid plumbed up correctly