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Hi any one got any idea what to do , the car is a 2 litre 2001 jdm Sti , it's been remapped when it's warm outside it runs fine boost is around 1.5 bar ish , when it gets cold Low revs around 3000 plus if it's floored it hits the boost cut , is there any thing in the Ecu that controls boost in relation to outside temperature or any other way of sorting this out , there is a way of adjusting the waste gate but does this effect the boost at all levels , I confess I don't understand the ins and outs of mapping
Tecso or shell sul and it's not made a difference, it was mapped in normal not overly hot cold uk weather , the mapper has adjusted it once and boost appeared to come done and then cold weather again it hit the cut , is appears to need the boost at 3000 reduced but will that reduce it across the range in all gears or just in 6th ?
vxr2010 said:
I've heard of the boost solenoids I thought they only increase boost and not reduce , and does it work alongside current control system or does it work alone , plus I assume the electronic one is the way to go if I'm looking at the right part ?
My car has a 3 port based on the recommendation of the engine builder. I understand that having a 3 port gives far more control of boost and far more precise control.It's probably worth getting some proper logging done on the car. I'll see if I can provide some useful information below but a couple of things tell me this might be more than something you can tune out. I wonder if it's possible you've got a very slight split in a rubber hose that's worse when cold (stiff).
I don't *think* that the 01 ECU had per-gear boost.
1) Do you mean you're idling at 3000rpm when cold?
2) Do you know where your boost cut is set? Mine's 35psi at sea level, which is no small amount of overshoot!
There's a take off from the inlet that's connected to the wategate actuator. If this were a direct connection, the car should theoretically not exceed the pressure set by the spring. This is only something like 6 or 7 PSI.
There is a T piece in the pressure line that bleeds some pressure away from the wastegate actuator, allowing the boost to exceed the pressure set by the spring. The amount of air is controlled by the boost control solenoid, which is controlled by the ECU. There are tables in the map that can adjust this system according to air temperature, barometric pressure etc etc.
As you can see - at lower intake temperatures (below 10C in this case), it reduces the WGDC (via the boost control solenoid) to effectively limit boost. This will only be effective if the WGDC has been tuned correctly alongside the target boost (if max wgdc is set too high, this table may have no effect).
This system is OK, but even on the standard maps it's a little prone to boost oscillations, overshoots etc etc - As the previous post says, 3 port setups are generally considerd a lot more accurate/stable.
Have a look at mine 2 port on a dyno doing it's kangaroo boost....
That was a combination of a gunked up solenoid and the ECU making adjustments faster than the engine would react to them (IMO, the old 01/02/03 ECU method of adjusting to target boost is more prone to this than the later ECUs). Half a can of carb cleaner and some adjustment in the mapping got most of this sorted, but you can still feel it flutter around a little).
On top of this, I'm aware that some STIs have a tendency to boost creep, as the wastegate struggles to get enough exhaust gas away from the turbo. I *think* this is mainly on the VF35 and is sorted with a combination of exhaust and porting.
I don't *think* that the 01 ECU had per-gear boost.
1) Do you mean you're idling at 3000rpm when cold?
2) Do you know where your boost cut is set? Mine's 35psi at sea level, which is no small amount of overshoot!
vxr2010 said:
I've heard of the boost solenoids I thought they only increase boost and not reduce , and does it work alongside current control system or does it work alone , plus I assume the electronic one is the way to go if I'm looking at the right part ?
The boost control solenoid is part of the standard boost control system. It's bolted to the suspension turret on the off side (under a black plastic cover on the bug eye).There's a take off from the inlet that's connected to the wategate actuator. If this were a direct connection, the car should theoretically not exceed the pressure set by the spring. This is only something like 6 or 7 PSI.
There is a T piece in the pressure line that bleeds some pressure away from the wastegate actuator, allowing the boost to exceed the pressure set by the spring. The amount of air is controlled by the boost control solenoid, which is controlled by the ECU. There are tables in the map that can adjust this system according to air temperature, barometric pressure etc etc.
As you can see - at lower intake temperatures (below 10C in this case), it reduces the WGDC (via the boost control solenoid) to effectively limit boost. This will only be effective if the WGDC has been tuned correctly alongside the target boost (if max wgdc is set too high, this table may have no effect).
This system is OK, but even on the standard maps it's a little prone to boost oscillations, overshoots etc etc - As the previous post says, 3 port setups are generally considerd a lot more accurate/stable.
Have a look at mine 2 port on a dyno doing it's kangaroo boost....
That was a combination of a gunked up solenoid and the ECU making adjustments faster than the engine would react to them (IMO, the old 01/02/03 ECU method of adjusting to target boost is more prone to this than the later ECUs). Half a can of carb cleaner and some adjustment in the mapping got most of this sorted, but you can still feel it flutter around a little).
On top of this, I'm aware that some STIs have a tendency to boost creep, as the wastegate struggles to get enough exhaust gas away from the turbo. I *think* this is mainly on the VF35 and is sorted with a combination of exhaust and porting.
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