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Discussion Starter #1
I have been informed that for my Nordic Stage 3 ECU I need to run at a basic boost of .45bar/6.5psi. Unfortunatley with this setting I get boost that fluctuates between 1.1 and 1.4 bar below 4krpm which is very anhoying. After observing the behaviour of my boost needle it would seem that the boost is rising rapidly to the 1.4bar limit and then suddenly cutting back to 1.1 bar before pushing up again and then cutting back etc. Above 4krpm it holds a steady 1.4 bar so it would seem that the fueling is not inadequate and neither is the WG being blown open from within. What I think is happening is that the very free flowing IC and exhaust is creating faster boost rise than the ECU expects and when it opens the BPC to divert pressure to the actuator it dumps too much pressure? I fitted an external helper spring to the WG and this raised base boost to .7bar/10psi. All conventional wisdom would suggest that this will create boost spikes ( which I already have anyway if I punch the pedal in 3/4/5) but what seems to happen is that once the ECU has learnt the limit it is holding higher boost with much more stability - 1.3-1.4bar. In the old days of c900 APC tunning it would be recommended that base boost is set to 1/2 the max boost so why do ECU tuners (except Abbott) recommend a base boost at stock settings. I still have the full WG movement and if I was encountering any knock the ECU would lower the boost by holding the BPC open to the WG? The BPC tests good, I'm using 97RON fuel, DI is new, plugs are new and correctly gapped. Any comments as I'm still not entierly comfortable deviating from Nordic guidelines.
 

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Shirozina said:
I have been informed that for my Nordic Stage 3 ECU I need to run at a basic boost of .45bar/6.5psi. Unfortunatley with this setting I get boost that fluctuates between 1.1 and 1.4 bar below 4krpm which is very anhoying.

...

What I think is happening is that the very free flowing IC and exhaust is creating faster boost rise than the ECU expects...
No. What is happening is that you have crappy software with wrongly tuned PID controller.

Your try of 0.7 bar of base boost probably does not work either because that most likely (depending on setting in the software) creates a situation where APC adaptation saturates and cannot compensate for highest boost point.
 

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Shirozina said:
I have been informed that for my Nordic Stage 3 ECU I need to run at a basic boost of .45bar/6.5psi. Unfortunatley with this setting I get boost that fluctuates between 1.1 and 1.4 bar below 4krpm which is very anhoying. After observing the behaviour of my boost needle it would seem that the boost is rising rapidly to the 1.4bar limit and then suddenly cutting back to 1.1 bar before pushing up again and then cutting back etc. Above 4krpm it holds a steady 1.4 bar so it would seem that the fueling is not inadequate and neither is the WG being blown open from within. What I think is happening is that the very free flowing IC and exhaust is creating faster boost rise than the ECU expects and when it opens the BPC to divert pressure to the actuator it dumps too much pressure? I fitted an external helper spring to the WG and this raised base boost to .7bar/10psi. All conventional wisdom would suggest that this will create boost spikes ( which I already have anyway if I punch the pedal in 3/4/5) but what seems to happen is that once the ECU has learnt the limit it is holding higher boost with much more stability - 1.3-1.4bar. In the old days of c900 APC tunning it would be recommended that base boost is set to 1/2 the max boost so why do ECU tuners (except Abbott) recommend a base boost at stock settings. I still have the full WG movement and if I was encountering any knock the ECU would lower the boost by holding the BPC open to the WG? The BPC tests good, I'm using 97RON fuel, DI is new, plugs are new and correctly gapped. Any comments as I'm still not entierly comfortable deviating from Nordic guidelines.
Actually, I think that your wastegate IS blowing open. The more free flowing your exhaust, the less pressure there is on the other side of the flapper to help hold it closed and the more air you are processing the more flow you will be running through the exhaust manifold.

The turbo can produce quite a bit more than 1.4 bar of boost low in the revs but after 4K the differential tightens as the flow demands of the engine begin to use most of what the turbo has to offer. The fact that it holds boost over 4K is not terribly surprising due to this fact.

I had issues with my wastegate blowing open for some time and was only able to rectify them with higher base boost. In my case, MUCH higher...but that's a long story.;)

I think you are on the right track. As I've mentioned before, most tuners require some additional strengthening to the wastegate actuator with their stage 3 and up. IIRC Maptun use a Forge unit in their upper stages.

D-
 

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Discussion Starter #5
Hi David, I'm not sure the WG is blowing open - I fitted an MBC the other day for a test and it held boost OK under 4krpm but then tailed off to 1.1 after 4k. It also produced much more low end power with the turbo building boost well below 2krpm which makes the car much more responsive to drive. Infact it was way faster and has oodles more torque but I'm slightly reluctant to run it again at this level as for some reason I may be getting knock in this high boost 2-4krpm region and this is why the boost is cutting back?. I've also bought another MAP sensor as someone suggested this may be getting slow to respond and also another BPC as even though it tests OK it may be faulty under actual driving conditions. As a last resort I'll refit the MBC and run at a peak boost of 1.1bar.
 

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Shirozina said:
Hi David, I'm not sure the WG is blowing open - I fitted an MBC the other day for a test and it held boost OK under 4krpm but then tailed off to 1.1 after 4k. It also produced much more low end power with the turbo building boost well below 2krpm which makes the car much more responsive to drive. Infact it was way faster and has oodles more torque but I'm slightly reluctant to run it again at this level as for some reason I may be getting knock in this high boost 2-4krpm region and this is why the boost is cutting back?. I've also bought another MAP sensor as someone suggested this may be getting slow to respond and also another BPC as even though it tests OK it may be faulty under actual driving conditions. As a last resort I'll refit the MBC and run at a peak boost of 1.1bar.
If you fit an MBC, you've managed to turn trionic into bionic.

AKA if you're getting knock, it's your foots responsibility to back off the go pedal as the car cannot manage boost anymore. The BPC is what allows boost to be controlled by the computer; Once you go Manual (Boost Controller), you've taken that safety net away...


-bny
 

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Discussion Starter #7
Thanks BNY - I do understand the potential dangers and limitations of an MBC and hence why I was going to only set a conservative 1.1bar limit - with my hardware and good fuel I think this is well within the safe envelope of the ECU to control any detonation with more fuel or retarded timing (it's bionic controls)
 

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Shirozina said:
Thanks BNY - I do understand the potential dangers and limitations of an MBC and hence why I was going to only set a conservative 1.1bar limit - with my hardware and good fuel I think this is well within the safe envelope of the ECU to control any detonation with more fuel or retarded timing (it's bionic controls)
Preaching to the choir =)

Batardized stage 4 autobox here pushing ~ 22 peak, 19 sustained on a td04.... running on a MBC and a little faith.

Listen for knock; Use good gas, roll with it.

also to note, I just toasted 2 exhaust valves a few weeks ago, so i've a new headgaket + machined head .... Make sure your vac lines and gaskets are swell!

But I agree; You're on bionic, as I am.

With some synapsys firing, we're both safe enough. I'd go to my levels, but it's not my car you're driving =)

-bny
 

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brewtide said:
If you fit an MBC, you've managed to turn trionic into bionic.

AKA if you're getting knock, it's your foots responsibility to back off the go pedal as the car cannot manage boost anymore. The BPC is what allows boost to be controlled by the computer; Once you go Manual (Boost Controller), you've taken that safety net away...


-bny
I'm claimng royalty rights here...

;)
 

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I have quite a few issues with the waste-gate blowing open and its a common problem with the weaker acutators. I would try a helper spring and test it. If it does not happen with 7-8psi of base boost, its a good sign that was you're issue.

I think the ebs's and mbc's can make better power and hold boost much better than those crappy t5 bpc's. I have had 3 fail and at 250.00 each, I am done with them for big power. I run the good gas, put in my w/m injection and listen for knock... I make much better power and it holds much better up in the higher rpm ranges.

I can also run 20psi for daily driving and then put in some 104 race gas and turn it up to 28psi and bust out 13.1's at 112mph in Denver at 6000'... Some common sense is needed, but mbc's and ebc's can be run safely and make better power!

John
 

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Discussion Starter #11
Lots of good advice here guys - I'd realy like to confidently eliminate knock as a source of my boost instability before I try to crank up the power. Is there any way of tapping into the T5 ECU to see if this is happening or monitoring it? On my c900 T16 I had an LED hooked up to the APC to show if there was any knock. As for listening out for it I always understood that the engine-grenading knock was inaudiable.
 

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Tech2 reads knock and its always a good idea to check your fuel pressure or at least your a/f ratio. I just posted about this on the 9k forum. I have found 4 bad fuel pumps in 3 years and it was under boost and heavy load that the fuel pressure would drop and make the car run lean!!!

On my ng900 the fuel pressure was fine to about 18psi of boost, then at 20-25psi of boost, the fuel pressure would fall back the other way and be from 70 back down to 40psi by 25psi of boost and gave mean lean a/f ratios...

Replaced the fuel pump with a new one... It too was bad right out of the box! Replaced it a second time, bam 75psi of fuel pressure and my a/f went from 13.8/1 to 11.7/1 under full boost of 25psi.

Last weekend I checked my 9k aero just to be safe... Holy crap, the a/f was 14.3/1 under full boost at 23psi, stage 3 ecu. No systems except a slight surging feeling. Put in a new walbro pump from eeuro and bam, it was worse, now it was 17.8/1 under boost at 15psi!!! I again go buy another walbro pump from Napa and lo and behold, 11.5/1 at 23psi of boost!!! That is 4 bad fuel pumps under boost in 3 years and if I had never checked it, I would have surely burned both of those motors down!!!

I say again, check your a/f.... I checked my girls cse last night, its weak too and not working correctly... Now I am on #5 bad fuel pump for me saabs!
Check your a/f and fuel pressure under boost
 

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Discussion Starter #13
I can hook up a fuel pressure gauge easily but a WB A/F meter is a bit more involved - maybe I should do it though as it would tell me a lot more about what's going on.
 

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Any obd2 logger will read saab's ECU
I use OBDlogger.com's. It's free, and one of the better ones.

You can't log knock, though. You have to watch timing. Timing should drop-back significantly, when the motor's loaded. Then, it'll climb as RPMs do (generally speaking) your ECU tuner may do things differently.

FWIW, I use my old DSM logger for the saab.
It's a palm m105, an obd2 diagnostic port adapter and palmenstein/obdlogger.com software.

Won't get much better than that.
 

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Discussion Starter #15
A data logger sounds even better - so all I need is a connection between my OBD II port and my laptop plus the software?
 

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Shirozina said:
I can hook up a fuel pressure gauge easily but a WB A/F meter is a bit more involved - maybe I should do it though as it would tell me a lot more about what's going on.
tech2 can read a/f and the knock and you could have a saab shop hook it up and tell you what is going on. You can also go to a dyno shop and have them put it on the wide band and do some pulls and see what is going on that way or you can now get the innovate wide-band stand-alone kit for 260.00 bucks from Nick at GS. ! That comes with the gage and everything you need to check your a/f with a good wide-band and it will be there if any problems every come back in the future! A good wide-band will tell you if you have bad fuel pressure because you will notice the lean mixtures.

I have 4 saabs and all of them have had bad or poor fuel pressure under boost.
I highly recommend to everyone to check you're a/f ratio to make sure you are not slowly melting your pistons down... Probably take a year or so if its just slightly lean to pretty quick if its in the 15's or higher.

John
 

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Shirozina said:
A data logger sounds even better - so all I need is a connection between my OBD II port and my laptop plus the software?
Yea, that is a great idea and I just got the innovate auto-box 3 so I can now log pressure, rpm, intake temp, duty cycle, a/f and egt!!! This will give me and my tuner enough information to really dial in the sw for my larger turbos. We will no longer be quessing and I will not only have good a/f info, I will have good egt info and boost and intake air temps and the whole 9.

This should allow me with NIRA or my tuner to get the sw dialed in very nicely I would say...;)

I was driving around the other night with my laptop on the passenger seat... I thought my name was Paul and I was fast and furious... Have you ever tried to work on your computer while you are driving? ITs tuff!

John

John
 

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Shirozina said:
Hi David, I'm not sure the WG is blowing open - I fitted an MBC the other day for a test and it held boost OK under 4krpm but then tailed off to 1.1 after 4k. It also produced much more low end power with the turbo building boost well below 2krpm which makes the car much more responsive to drive. Infact it was way faster and has oodles more torque but I'm slightly reluctant to run it again at this level as for some reason I may be getting knock in this high boost 2-4krpm region and this is why the boost is cutting back?. I've also bought another MAP sensor as someone suggested this may be getting slow to respond and also another BPC as even though it tests OK it may be faulty under actual driving conditions. As a last resort I'll refit the MBC and run at a peak boost of 1.1bar.
That IS curious Shirozina. I'll have to think about that a bit.

I still wonder...since the BPC is a bleed type valve, could it be causing some "pre-load" on the actuator early in the rev range which in turn causes the actuator to blow open but then as soon as the engine is using most of the turbos out put it holds pretty well?

Then when you install the MBC you get the opposite problem...holds boost low because it doesn't bleed any boost signal to the actuator but once target boost is reached, it too bleeds boost and pre-loads the actuator line making it easier to open the flapper with pressure from inside the exhaust manifold in the upper revs.

...???? I'm just thinking out loud.;)

D-
 

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Shirozina said:
Lots of good advice here guys - I'd realy like to confidently eliminate knock as a source of my boost instability before I try to crank up the power. Is there any way of tapping into the T5 ECU to see if this is happening or monitoring it? On my c900 T16 I had an LED hooked up to the APC to show if there was any knock. As for listening out for it I always understood that the engine-grenading knock was inaudiable.
There are two kinds of events that commonly get labeled "knock". They are VERY different!

One is pre-ignition.

The other is detonation.

Pre-ignition gives little or no warning before trashing internals.

Most engines, including Saab engines, can and do endure mild levels of detonation through the course of their life.

Here's a link to some excellent information to help:

http://www.streetrodstuff.com/Articles/Engine/Detonation/

Have fun!

D-
 

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Discussion Starter #20
Hi David,
The BPC definatley preloads and partialy opens the WG in the lower revs as with a stiffer spring and or MBC the spoolup is much faster and starts much lower in the rev range. I was reading some info on a 9000 forum and someone had observed movement of the WG at even 1/2 base boost with a T5.
Saab probably do this to lessen torque load on the gearbox but also to lessen tourque steer and other nasty handling traits that the stock chassis is prone to. I realy need to know what the ECU is doing in this 2-4k bosst range before I do any more adjustments so some form of data logger will be needed - I just need to know which one ( I feel another post coming on!)
 
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