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Discussion Starter · #1 ·
hi all, a quick question relating to actuators, i have a 96MY aero, with maptun stg 1 and no other mods, , i find that the max boost seems to vary quite a lot and i recon the actuator may not be holding the wastegate shut under full boost,

Should i just buy a standard one? or should i get an upgraded one?
 

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Hi there,

When you say the max boost varies quite a bit, can you expand further on what happens.

Do you notice that the boost hits its peak and then tails off rapidly ? or is it not always hitting the same level of boost ?

I did uprate the actuator on my 9000, as in my opinion it was not holding enough boost long enough, replacing the actuator enabled the required level of boost to be held much longer.
 

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Discussion Starter · #3 ·
Hi, saab90002.3t,
well after the ecu being fixed to stop the overboosting, i notice that the guage can oscillate on full boost, like the guage swinging back and forward, (not by a massive amount)on occasion the needle will go to the end of the red, other rimes, half way into red (under same conditions). There is always a little overswing, but i dont think max is the same every time. I am in the process of getting another boost gauge so i can quantify exactly what is going on, but from using the cheap tim gauge i had, it appeared max boost was approx 1.5, however, dont qoute me on that.
Is it the case that an upgraded actuator has a stronger spring, if so, is overswing an issue?
what im trying to get at is, if the spring is stronger to hold peak boost, does the solenoid need to try harder to open the wastegate hence maybe not catching overswing in time?
 

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I ran into a similar situation with my 9-3 on the second custom ECU programming at Hirsch. At full boost, now set at 1.15 bar, the boost pumped up and down throughout the rev range above 2800 rpm. After they did some considerable testing on the dyno they fixed my problem by sending an uprated wastegate actuator. I installed it and the boost was under full control again, with no pumping.

Now that I reread your post, it sounds like you might just be seeing the variance in the gauge. My 9-3 seems to do the same as you describe but actual power still feels the same. It is probably best you get an accurate boost gauge to get a better idea of what is happeneing.

I also agree with a Stage 1 only, your standard wastegate actuator should be enough. But yes, an upgraded actuator will have to be run with higher base boost due to the higher spring tension.
 

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Discussion Starter · #7 ·
hi eric, so am i correct in thinking your bb is set higher than stock? if so, how high is it, and what are the negative points of this
 

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Hirsch told me to just make sure I put the rod to the same length as the stock actuator so that there would be the correct amount of preload. Stock base boost on my car was about 1/2 yellow or about 5 psi. With the actuator set per Hirsch's instructions, base boost is now close to full yellow or about 11 psi.

Driveability is the same with the only issue being the cruise control hunts up and down when going uphill. I presume this is because it gets more boost pressure than it shoots for so then it backs off and then doesn't get enough, and so on. It really doesn't bother me much now as North Dakota doesn't exactly have many hills.
 

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You can't reduce base boost.

At the risk of labouring the point, Chris, unless you have software specifically mapped for a higher base boost an uprated actuator is likely to cause you problems. Most are sold to tuning applications that don't have the complexity and control of Trionic and use rather more coarse boost control methods.
 

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Discussion Starter · #11 ·
reading over my previous thread it should have said reduce boost, not bb, its not really labouring the point as im clear that software would require attention if fitting an upgraded actuator. However, i was curious how eric dealt with the occasion that bad fuel may be used, if the bb is quite hight.
 

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The ecu will only be able to reduce down to base boost. This has to be seen as a risk although, I feel a small one at that. Reason being is that the ecu can retard timing and pump even more fuel into the engine if it needs to. And yes, I don't think you should need an upgraded wastegate actuator unless your tuner sees the need for it.
 
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