1.25 bar of boost but 0-100 in 11s? - SaabCentral Forums
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  #1  
Old 2nd April 2019
MessingWithMySAAB MessingWithMySAAB is offline
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Default 1.25 bar of boost but 0-100 in 11s?

As the title says my SAAB is dog slow.
Me with my friends were riding my SAAB when we decided to do a 0-100 and it took 11s to get there.
My dad's '97 Mercedes Vito does better than that.
My car has LPG installed and the LPG injectors are on their way out, this most certainly is a problem.
But what i'm interested in is what makes it go so weak?
I did my 0-100 on gasoline, my turbo gauge was in the middle of the red (~1.25 bar), so boost was there, fuel was there (because gasoline), the only thing left would be the ignition timing i suppose?
No check engine comes on but it feels like my SAAB wants to limp more than anything, is there something that the LPG triggers that makes it go into this state?
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Old 2nd April 2019
EdT EdT is offline
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It is not possible for us to tell what is going on. But here are some things.
  1. How many friends did you have in the car? More weight = slower car.
  2. The boost gauge really should go to the top end of the orange scale under full boost.
Since you have an LPG conversion which most of us are totally unfamiliar with, we can only guess. For one thing, check if the throttle plate is opening fully when the accelerator is depressed all the way. Also, check that your turbo wastegate is working properly. I don't know how much of the original T5 system is in place and working now. If it is not controlling boost, what is?
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  #3  
Old 2nd April 2019
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Quote:
Originally Posted by EdT View Post
It is not possible for us to tell what is going on. But here are some things.
  1. How many friends did you have in the car? More weight = slower car.
  2. The boost gauge really should go to the top end of the orange scale under full boost.
Since you have an LPG conversion which most of us are totally unfamiliar with, we can only guess. For one thing, check if the throttle plate is opening fully when the accelerator is depressed all the way. Also, check that your turbo wastegate is working properly. I don't know how much of the original T5 system is in place and working now. If it is not controlling boost, what is?
All good advice. I’d add that if you’re not getting enough fuel, that is obviously a problem... Not sure if you have a way to check air/fuel ratio under boost, but a lean mixture is more prone to detonation/pre-ignition, even with a higher octane fuel like LPG. Bottom line, the fire needs fuel to make power.
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Old 2nd April 2019
jvanabra jvanabra is offline
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Yeah, it's going to be difficult to understand what may be in play. 1.25 bar is way more than stock, so there are some unaccounted for variables here. Without knowing what hardware and what software has been added it'd just be a lot of guessing.
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Old 3rd April 2019
MessingWithMySAAB MessingWithMySAAB is offline
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All of the original T5 is there, the LPG injector controller only measures the pulse width given by the T5 and calculates the appropriate mix for LPG.
So if i switch it off, via the button on the dash it basically lets the T5 do it's thing.
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Old 3rd April 2019
jvanabra jvanabra is offline
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Quote:
Originally Posted by MessingWithMySAAB View Post
All of the original T5 is there, the LPG injector controller only measures the pulse width given by the T5 and calculates the appropriate mix for LPG.
So if i switch it off, via the button on the dash it basically lets the T5 do it's thing.
Mmm.... but that's not what's happening. A FPT runs about .75 bar stock, so if you're seeing 1.25 bar then there are other factors in play. I am pretty sure the only way you get beyond 1 bar of boost is if software has been modified.
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  #7  
Old 3rd April 2019
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Quote:
Originally Posted by MessingWithMySAAB View Post
All of the original T5 is there, the LPG injector controller only measures the pulse width given by the T5 and calculates the appropriate mix for LPG.
So if i switch it off, via the button on the dash it basically lets the T5 do it's thing.

Thanks, that makes it a little simpler.

You say in your signature that your car is "Stage 2". Is that the case?

Even an untuned car will push the turbo needle on the dash to the far end of the orange zone. My stock "low output" B235E does that.

If you can't get the turbo needle past, say, halfway, then there is something wrong going on, and there are many people who have investigated, and we hope fixed, low boost on a T5.

I will also add that your 0-100 time can be in error, depending on how exactly it was measured. You can really only say that your car is slower than your father's Mercedes Vito (what is that? I had to look it up) if you loaded it up with an equal number of passengers, and raced each other from a stop.

This is actually why I like to take my cars to a drag strip, in fact the same drag strip. The numbers may not be exactly the same as I would get at another drag strip, never mind what is published in magazines or bragged about online. However, it gives me consistent results. I can compare different cars that I have taken to that drag strip, and I can compare modifications to a car, possibly trying multiple modifications in one day at the drag strip.

(My 1997 900S 2.3 non-turbo runs about 16.9s at 82 MPH. I don't try to launch it brutally, so my 60' time is 2.5 or 2.6s [if you have run a lot of cars, you know how miserably slow that is, and how much it will affect the final quarter-mile time]. That compares to around 15.0s at 91.5 MPH for my old Trans Am while it had dual exhausts, and 15.4s at 89 MPH when it had a more restrictive, but less troublesome and annoying single exhaust. Or 18.9 s at 71 MPH for my Plymouth Reliant station wagon.)

I have been meaning to get around to taking my 2003 9-5 wagon to the drag strip--this spring for sure!
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Old 3rd April 2019
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Quote:
Originally Posted by jvanabra View Post
Mmm.... but that's not what's happening. A FPT runs about .75 bar stock, so if you're seeing 1.25 bar then there are other factors in play. I am pretty sure the only way you get beyond 1 bar of boost is if software has been modified.

Maybe it's 1.25 bar absolute, or 0.25 bar boost above typical atmospheric pressure? T5 has MAP (Manifold Absolute Pressure), right?
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Old 3rd April 2019
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I guess we don't know where the reading of 1.25 bar is coming from. You'd definitely see different results from an OBDII tool reading the MAP sensor than a mechanical boost gauge connected to the manifold. Those mechanisms are not the same.
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Old 3rd April 2019
MessingWithMySAAB MessingWithMySAAB is offline
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It says right next to my saabs that it's a stage II NG900.
Stage II on B204 with TD04 means 1,25 bar.
Last time i checked OBDII said it's somewhere between 17-18 Psi.
Turbo gauge goes in the red when boost comes on.
As far as i know:
Green: vacuum.
Yellow: boost 0-1 bar.
Red: boost 1 bar and up.
I thought about posting this in the performance section but there's nothing "performance" about 0-100 in 11s.
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  #11  
Old 3rd April 2019
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Quote:
Originally Posted by MessingWithMySAAB View Post
It says right next to my saabs that it's a stage II NG900.
Stage II on B204 with TD04 means 1,25 bar.
That is not really accurate. "Stage II" means nothing. It's just a term whomever tuned your car applied to that tune. The specifics of "Stages" will vary from tuner to tuner, so we can't really know anything just by you saying "Stage II."

On that note, some tuners are do really crappy work, changing only max boost without implementing the other timing and fuel changes necessary to support it. That often ends up kind of where you are - with big boost but no actual performance to go with it.

To know more, I would think you'd really need to dive in and get some details about the tune and collect some running data from Trionic. Speculating about all the possible variable of a software tune isn't going to get you any answers.
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  #12  
Old 4th April 2019
MessingWithMySAAB MessingWithMySAAB is offline
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Quote:
Originally Posted by jvanabra View Post
That is not really accurate. "Stage II" means nothing. It's just a term whomever tuned your car applied to that tune. The specifics of "Stages" will vary from tuner to tuner, so we can't really know anything just by you saying "Stage II."

On that note, some tuners are do really crappy work, changing only max boost without implementing the other timing and fuel changes necessary to support it. That often ends up kind of where you are - with big boost but no actual performance to go with it.

To know more, I would think you'd really need to dive in and get some details about the tune and collect some running data from Trionic. Speculating about all the possible variable of a software tune isn't going to get you any answers.
It's the bog standard T5 Suite stage II autotune.
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  #13  
Old 4th April 2019
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Check boost pressure valve and its wiring. Sounds that you have only base boost.
You have already double-checked that you do not have brake lights on all time?
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Old 4th April 2019
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Try to disconnect W pipe from boost pressure valve.
Test and report back.

Do not left pipe unhooked, because you just removed main security feature.
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  #15  
Old 5th April 2019
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4 things I can think of:

1. The boost gauge is reading way off and you're actually getting hardly any boost.

2. Not enough fuel getting in. Can you revert to petrol to see if it still acts that way?

3. Blocked air filter.

4. Blocked cat or something else in the exhaust. If you're running LPG you don't need the cat.
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Old 5th April 2019
jvanabra jvanabra is offline
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Yep, those things or


5. Low compression


6. Poor ignition


7. Bad O2 sensor masking A:F problems


Now is the time where you need diagnostic tools - an OBDII reader (or t5suite) to monitor engine function. WBO2 to monitor A:F. A way to pressure/volume test the intake and exhaust. A compression or leakdown test to observe head & bottom end health. Maybe some parts swapping - plugs, DIC - where empirical tests aren't possible.
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  #17  
Old 6th April 2019
EdT EdT is offline
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Remember, we do not see your car, we just know what you describe.

First of all, how did you measure the 0-100 number, and does it really feel slower than your father's Mercedes?

Second, you mention you have LPG injectors....are those separate from the gasoline injectors? (I would guess so, but we don't really run this conversion around here.)

If the car is really running 1.25 bar boost (not intake pressure) and is really slow, then there is obviously an issue that has to be figured out. However, I would want to clearly establish that both things are definitely true.

By the way, how much weight does the LPG tank add to the car?

An NG900 has a basic weight of 1500kg, give or take depending on options (probably less). If the LPG tank and equpment adds 100kg, and you have some friends in the car, maybe 250kg worth, you have now added 350kg or almost 25% to the weight of the car. That will definitely slow you down.
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  #18  
Old 27th April 2019
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0-100 is 0-60, look where he is from. Not MPH but KPH.
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