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Discussion Starter #1
i have fitted my saab 9-3 2.0 lpt (my98, 53000mls) with a maptun stage 1 and with koni/eibach suspention in the previous week. I am pretty happy with the whole setup.

However. WOT in 4 and 5 does not give a smooth acceleration. It feels like the power is building up rapidly then lost a bit then builds up again and so on until i release the throttle.

Is this part of the adaption proces, has my wastegate actuator died or is my DI cassette kind of losing it, or what else can it be?

erik
 

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Are you using high enough octane gas? It sounds similar to what happens when the engine sees detonation. It retards the boost/timing, and then slowly builds up again until it detonates again.

This is hopefully not to case, but when you upgrade LPT with an MapTun chip you'll want to run the highest octane gas you can get, or at least higher than before. Probably the same gas the High Output motors use. I'm sure AMapTun talked with you about that, but just in case.

Cheers,
Dubbya~

edited for poor observation
 

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Discussion Starter #3
yeah, forgot to mention that. I am using 98 octane fuel ever since i bought the car which was 3 months ago.
 

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Might check the base boost to see if it's setup right. Sounds like some kind of actuator related issue. Base boost can cause similar symptoms. Though I'm sure someone will come along with a definite answer, or more advice soon.

Dubbya~
 

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The fluctuation doesn't seem to be abrupt enough to blame the fuelcut for the hesitation.

When the APC is adjusting boostpressure, it can be seen on the boostgauge, but it's hard to feel in higher gears. Since a LPT has no gauge, you really feel it.

I remember Eric B. having boost problems when doing testruns on the Hirsch dyno. The boost going up and down was caused by a faulty wastegate actuator.
 

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Welcome to Saabscene

It is possible your APC solenoid is on the way out which would have the effect of erratically cutting the boost. The other common fail point which can give these symptoms after a Trionic upgrade is the Direct Ignition cartridge.

If you do a search of these forums you'll probably find similar symptoms to yours listed.
 

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By your explanation, it sounds to me like the same problem that I had when I got my custom Hirsch ECU remapped last summer. It did indeed turn out to be a weak wastegate actuator. They sent me an upgraded unit when they determined the cause was not the programming in the ECU.

The reason you don't feel the boost surge in the lower gears is that the engine doesn't spend much time in those at WOT. Also, if the actuator is the problem and the boost is pumping up and down, you should probably see the boost level fluctuate on the gauge.
 

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Discussion Starter #8
I checked all the vacuum hoses. They're ok. I felt the wastegateactuator and I can move this to the right (with a little force) smoothly.
 

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Originally posted by Vigge:
[qb]Does your stock boost gauge "rattle" under WOT.
If so you actuator spring is too weak. [/qb][/b]
Interestingly, I know that my standard actuator is too weak, but my original boost gauge does not rattle. Having fitted an additional graduated boost gauge I have noted that this one does rattle.
 

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Originally posted by /john:
[qb] QUOTE
Originally posted by Vigge:
[qb] Does your stock boost gauge "rattle" under WOT.
If so you actuator spring is too weak. [/qb][/b]
Interestingly, I know that my standard actuator is too weak, but my original boost gauge does not rattle. Having fitted an additional graduated boost gauge I have noted that this one does rattle. [/qb][/b][/quote]Ok there might be some limitatios to that theory, but it applies in most cases.

And what comes to your graduated boost gauge, are you sure that it is not the gauge that is playing a trick on you. For instace squuze the vac line with a zip tie and see if that helps with the rattle. You might also try to isert the tread piece of a screw into into the gauge end of vac line. Fuel filter from small engines work as well. I have some videos if you want to where a gauge rattles and its due to the gauge not the car.

Is your 9-3 with T5 or T7?
Since I dont remember your case from the past, how did you come to the conclusion that your actuator was endeed too weak?
 

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Originally posted by Vigge:
[qb]And what comes to your graduated boost gauge, are you sure that it is not the gauge that is playing a trick on you. For instace squuze the vac line with a zip tie and see if that helps with the rattle. You might also try to isert the tread piece of a screw into into the gauge end of vac line. Fuel filter from small engines work as well. I have some videos if you want to where a gauge rattles and its due to the gauge not the car.[/qb][/b]
Vigge - I was trying to add information to your theory - not detract from it


Originally posted by Vigge:
[qb]Is your 9-3 with T5 or T7?
Since I dont remember your case from the past,  [/qb][/b]
Trionic 5

Originally posted by Vigge:
[qb]how did you come to the conclusion that your actuator was endeed too weak? [/qb][/b]
Because I was supplied an uprated actuator with the upgrade as the tuning company advised the standard one is too weak and would not be able to hold the boost pressure.

Unfortunately, the uprated actuator was faulty and I am awaiting the replacement.

Therefore I know that I am running on an actuator that is too weak.
 

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Originally posted by /john:
[qb]Vigge - I was trying to add information to your theory - not detract from it  
 [/b]
Sorry I missread your answer

Originally posted by Vigge:
[qb]Is your 9-3 with T5 or T7?
Since I dont remember your case from the past,  [/qb][/b]
Trionic 5

Because I was supplied an uprated actuator with the upgrade as the tuning company advised the standard one is too weak and would not be able to hold the boost pressure.

Unfortunately, the uprated actuator was faulty and I am awaiting the replacement.

Therefore I know that I am running on an actuator that is too weak.    [/qb][/b]
Which company does your upgrade come from?
And what mods are you running?
 

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The original problem certainly sounds like a weak actuator spring to me. They can deteriorate in performance and get more "saggy" over time. Shortening the rod may cure the associated problem of lower base boost, but does nothing to help prevent the wastegate opening under exhaust gas pressure.

The OEM gauge is quite heavily damped. If you use an aftermarket one, and see a lot of "vibration", it's genuinely reading variations in intake pressure. Mine has become worse as I have developed a problem with a significant compression inbalance (currently being sorted
). Pinching the supply hose to restrict the flow does help to damp such variations.
 

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Discussion Starter #16
hai again,

it seems to be the wastegate actuator. i am now waiting for a replacement non-oem part.
Hope this will solve it.
 
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