Possum Link Boost Problem.
19 March 2000, 03:31 PM
#1
Guest
Posts: n/a
I have been using Link ECU for some months now and was tuned by a tuner from Oz.This tuner told us that it's ok to control the boost through an electronic boost controller and he adviced this set up ie Link work in conjunction with an EBC.
I have fitted the factory 3 port wastegate solenoid and this way the Link ECU can now control boost.I found that the boost is more aggressive and better response than my EBC.The only problem I have at the moment is that the boost keep overshooting to 1.6 bar(23psi) before full throttle.I have fitted Knock Link too,no knock registered so far.I have tried a few setting on the boost zone but overboosting problem still there.No such problem with EBC but suffered poor response.Have checked that the 3 port solenoid is in working order.
Any advice to solve my over boosting problem will be greatly appreciated.BTW,turbo is Garrett 400hp and car is MY98.TIA.
I have fitted the factory 3 port wastegate solenoid and this way the Link ECU can now control boost.I found that the boost is more aggressive and better response than my EBC.The only problem I have at the moment is that the boost keep overshooting to 1.6 bar(23psi) before full throttle.I have fitted Knock Link too,no knock registered so far.I have tried a few setting on the boost zone but overboosting problem still there.No such problem with EBC but suffered poor response.Have checked that the 3 port solenoid is in working order.
Any advice to solve my over boosting problem will be greatly appreciated.BTW,turbo is Garrett 400hp and car is MY98.TIA.
19 March 2000, 04:19 PM
#2
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Hi,
You should be able to reduce the boost overshoot by enlarging the flow restrictor found in the control hose that runs from the compressor exit to the boost control solenoid.
Is the turbo a complete garrett unit, or a hybrid of garrett internals in an IHI shell?
Moray
You should be able to reduce the boost overshoot by enlarging the flow restrictor found in the control hose that runs from the compressor exit to the boost control solenoid.
Is the turbo a complete garrett unit, or a hybrid of garrett internals in an IHI shell?
Moray
19 March 2000, 04:33 PM
#3
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Though the conversation below is about the MIATALINK, it might also apply (at least the theory) to the POSSUMLINK as well. AFAIK the procudure for setting the WG sensitivity is in the manual and is the same for both
products.
> It's been pretty nice here in Chicago for the last week so i've been out
> doing some tuning and trying to get things running right for the coming
> summer. The one thing that I can't quite figure out is how to get my boost
> controller set up correctly for high boost. I have boost set at 220 kpa
and
> what seems to happen is the boost will shoot up to between 16psi and 18psi
on
> the gauge and then suddenly drop to 10 psi. It then proceeds to rise again
> then fall again. This is most predominent in 4th or 5th gears. It seems to
me
> that the boost solenoid is overcorrecting? When I set the boost to 200kpa
> this seems to go away.
Most likely the WGsens is set too high, but ....
To set up the boost control, first note the boost level attained
with the solenoid valve disconnected at WOT and 5K RPM in 5th gear. Enter
that value in the WGbase screen. Connect the solenoid valve. Temporarily
set WGrpm to 7500 and see how much boost you now get at WOT and 5K RPM in
5th gear. If the boost is too high, reduce WGsens until boost is
correct. If the boost is too low, increase WGsens until boost is
correct. Now set WGrpm to whatever RPM your system first reaches
target boost in 5th gear. The ECU has to measure atmospheric pressure in
order to get consistent results, and it does this using the MAP sensor
when you first turn the key on. Make sure you wait until you hear the
fuel pump relay click on before hitting the starter or else the atmospheric
pressure reading will get screwed up. When testing the setting of WGsens,
floor it at 2500 RPM and see what maximum boost you reach by the time you
get to 5K. This will prevent transient spikes from confusing the
measurements. WGsens should end up somewhere around 80-100. If your
WGsens has to be below 50 to keep the boost from going too high, add a
restrictor to the exhaust (unused) nipple of the solenoid valve. The
smaller the restrictor the higher WGsens will need to be.
> Bill told me to enter the base boost in Z14 not WG BASE because thay are
> different. Is this true?
>
> My WG SNS is at 43. 80-100 sounds really high.
The number in Z14 is the WG spring pressure, i.e. WG BASE minus atmospheric
pressure. The ECU will calculate that and set Z14 for you when you set WG
BASE
as described. It is also OK to set Z14 directly if you prefer, but remember
to
subtract atmospheric pressure first (and it's not 100 where you are!). WG
BASE
will change a little on future days when atmospheric pressure changes since
it
will always be the sum of Z14 (which doesn't change) and atmospheric
pressure
(which is re-measured every time you turn on the ECU power). Be sure to
wait a
second or so after turning the ignition on before you hit the starter so
that
the atmospheric pressure measurement (with the MAP sensor) won't be
disturbed.
products.
> It's been pretty nice here in Chicago for the last week so i've been out
> doing some tuning and trying to get things running right for the coming
> summer. The one thing that I can't quite figure out is how to get my boost
> controller set up correctly for high boost. I have boost set at 220 kpa
and
> what seems to happen is the boost will shoot up to between 16psi and 18psi
on
> the gauge and then suddenly drop to 10 psi. It then proceeds to rise again
> then fall again. This is most predominent in 4th or 5th gears. It seems to
me
> that the boost solenoid is overcorrecting? When I set the boost to 200kpa
> this seems to go away.
Most likely the WGsens is set too high, but ....
To set up the boost control, first note the boost level attained
with the solenoid valve disconnected at WOT and 5K RPM in 5th gear. Enter
that value in the WGbase screen. Connect the solenoid valve. Temporarily
set WGrpm to 7500 and see how much boost you now get at WOT and 5K RPM in
5th gear. If the boost is too high, reduce WGsens until boost is
correct. If the boost is too low, increase WGsens until boost is
correct. Now set WGrpm to whatever RPM your system first reaches
target boost in 5th gear. The ECU has to measure atmospheric pressure in
order to get consistent results, and it does this using the MAP sensor
when you first turn the key on. Make sure you wait until you hear the
fuel pump relay click on before hitting the starter or else the atmospheric
pressure reading will get screwed up. When testing the setting of WGsens,
floor it at 2500 RPM and see what maximum boost you reach by the time you
get to 5K. This will prevent transient spikes from confusing the
measurements. WGsens should end up somewhere around 80-100. If your
WGsens has to be below 50 to keep the boost from going too high, add a
restrictor to the exhaust (unused) nipple of the solenoid valve. The
smaller the restrictor the higher WGsens will need to be.
> Bill told me to enter the base boost in Z14 not WG BASE because thay are
> different. Is this true?
>
> My WG SNS is at 43. 80-100 sounds really high.
The number in Z14 is the WG spring pressure, i.e. WG BASE minus atmospheric
pressure. The ECU will calculate that and set Z14 for you when you set WG
BASE
as described. It is also OK to set Z14 directly if you prefer, but remember
to
subtract atmospheric pressure first (and it's not 100 where you are!). WG
BASE
will change a little on future days when atmospheric pressure changes since
it
will always be the sum of Z14 (which doesn't change) and atmospheric
pressure
(which is re-measured every time you turn on the ECU power). Be sure to
wait a
second or so after turning the ignition on before you hit the starter so
that
the atmospheric pressure measurement (with the MAP sensor) won't be
disturbed.
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