first off, stage 4 isn't going to be 300whp, it will be around 255-270 whp.

To limit boost you could just unplug the BPC and run base boost, or if your car is Trionic 5 you can stick a manual boost controller in there and turn the boost down (just be sure to also unplug the BPC or you can fry it - I've done this twice now )

 

To limit boost you could just unplug the BPC and run base boost

Thats what I would do. Quick and easy.

 

You could get another ECU and swap it in for the tuned one (takes only a few minutes)... but then you run the risk of being dangerously rich or lean.

 

You could get another ECU and swap it in for the tuned one (takes only a few minutes)... but then you run the risk of being dangerously rich or lean.

No you don't.

You can run a stock ECU in a car with stage 4 hardware with no problems at all. Bad/misleading info with that statement

 

install a switch that opens the BPC circuit, limiting the car to base boost

 

So okay, i have a dual stage/switched mbc right now, are we talking about just opening that thing up all the way, that shouldn't work, as then it would be just turning it back into an open pipe, therefore running off of the ecu again. Might as well have no mbc at all.

And unplug the BPC? how so? do you mean one/several tubes or the electrical connector? JK, what were you doing that killed a couple of these things?

So there are three tubes, one to the wastgate, one to the turbo housing and... im not sure. But it seems like in all of these cases using an mbc will cause the bpc to think boost is lower than it really is. Not higher.

Thanks

 

Unplug bpc == electrical connection.

With no power, it can't control t3h boost.

 

If you wanna get fancy, you could hook a switched evap purge valve into the wastegate line.


I think Eric did something like that on his red viggen.

 

palmer, wouldnt that do the same thing as putting in an MBC, cause cause the bpc to go on the fritz?

i still think a switch to open/close the BPC electrical connection is the easiest/cleanest way to do it

 

I swear someone has done it.


I rigged up a BPC switch on my C900. It worked very well.

 

It was eric on his red ng with the vig bumpers.
Cant find his site now...

Edit: here you go http://www.ericsaabsite.com/Upgrades/Stage3/BoostControl.html

 

What eric did (from what I remember) is use the valve to switch between manual boost control and BPC boost control without having to physically remove the MBC.

The way I fried my BPCs was by plugging in a MBC without unplugging the electrical connection to my BPC.

I had a working BPC, installed my MBC. I drove it for about 20 miles before I remembered that I had not unplugged the BPC. I took the MBC out and hooked the vac tubes up to the BPC and it was already too late, it was stuck wide open. For some people this does not seem to happen, but it happened twice for me.

 

Just unplugging the electrical connector to the BPC is the quickest route and will do the job.

 

Yes, easiest, most simple, and very effective. K.I.S.S. is the best method in my opinion. No sense in making things complicated just for the sake of making them complicated

 

yes, unplugging the bpc is the simplest route, but having to pop the hood every time would be a pita, plus the wear on the connector.

 

A person with a tune or custom go-fasties should be checking fluids and the general state of things under the hood once a week anyway. I don't think wear will be a factor on the connector. Keep a bit of dielectric grease on it and I bet it wouldn't wear at all.

 

ya, stage 4 hardware on a stock ECU makes for an unhappy car. Fuel cut happens faster than you'd think, and suddenly you're biting the steering wheel. I know from experience

 

JK knows his stuff that is for sure. Replace the MAF and go back and check your MAF and I'm sure that you'll see the A/F will be nearly spot on.

 

I don't know as much as many people on here, but I know what I have seen on quite a few dynos done on stock cars, and cars that were "done wrong" like mine.

I found it a bit interesting that with my tune my A/F is actually a 12.0:1 to 12.5:1 right now, whereas when I was using a stock tune for a smaller turbo I was running pretty rich.

Ether way, after seeing slspf2's dyno I would definatly look into some sensor issues. There is no reason that a larger exhaust and a turbo that flows 8% more would cause a car to run that lean as long as the sensors are reading correctly. It just should not run that lean as long as the car is knows how much air and how much fuel is flowing through...at least that is my understanding.

What I know is that I have seen dyno slips from cars with stock software that obviously does not match the hardware, but T7 and T5. I doubt that those instances are flukes, but as always, its a risk you have to take when dealing with aftermarket parts and/or a situation where you bump the power output over the stock level. That's all I can say about this for sure.

 

i hit fuel cut because the td04 would spool and build pressure faster than the car could handle. I think the wastegate actuator i have on there is a little sticky, but i definately hit fuel cut

 

I had the same issue as you.


It was a bad MAF.

60k is the change interval.

 

So youre saying unplugging the bpc will lower the car's boost. Seems weird, but then again, i really dont know the internals of these things.

And JK, Ive been running a dual stage/switchable mbc set up for a month or so now... nothing bad so far, but thanks, i will keep an eye out!

 

So youre saying unplugging the bpc will lower the car's boost. Seems weird, but then again, i really dont know the internals of these things.

Technically, yes you are lowering max boost. No bpc means the only thing controlling boost will be the spring in the wastegate actuator. So depending on what your base boost is set at that could be anywhere from 6-8psi.

 

When the BPC has no power/signal from the ecu it can't contorl the piston via magnetics and it therefore is supposed to blow straight open to the wastegate port as a fail safe leaving you with baseboost. Thats the reasoning behind it.

 

On my T7 9-5, I have a 5cm td-04, 3" downpipe, FMIC, saabsport catback and intake.

Its been run on the stock LPT ecu and shown to be slightly rich on the dyno.
I have it now on a 2000 saab sport ecu, and i have not dyno'd it yet, but i would garuntee that it also runs rich.
With an SQR Stage 4 Ecu, it definitely dumps fuel on the top end like nobody's business, really rich

So, I will say with complete confidence that t7 can correct and adapt for hardware changes without running lean, as I have run my same hardware setup on all the different software, and 2/3 are dyno proven. And I would be very sure that this setup is as well.

 

I believe it. I only commented that he might run lean originally due to the fact that I am currently experiencing that problem, though wrongly diagnosed.

Unfortunately it is apparent that the Saab mechanics in StL don't know what to look for in a check engine light... they didn't even see a bad MAF as a remote possibility.

 

Also, I worried about the same thing going stage 4, if other people happened to drive it. My mom has driven the car and has NO idea...

 

Hahaha, exactly what im looking for! thanks guys, im gonna just hook up a switch to my change switch (i pulled apart the change holders in the cup holder and installed a push switch at the bottom of the quarter slot, completely hidden)