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Discussion Starter · #1 ·
i have a MapTun stage 3, with all the necessary hardware. I just acquired abdukted's stg3+ ecu and a td04hl-15t. I have a couple of questions that i hope some of you might be able to answer:

1. The software calls for a 3.5 bar fuel pressure regulator, i've got it. but i recently got a really really really good deal on some bosch green giant injectors. like NIB for $150 good. Can I put them in too, or will changing injectors need a whole new tune?

2. I don't have the larger intercooler yet. just the stock viggen IC. Will this be an issue, or can i do my install and keep saving up for that IC?

3. Last one i promise...i noticed the part numbers for the MAF sensor between the base (B204L 47 80 185) and the SE (B205R 91 73 386) are different. will i be needing a new MAF as well? Your expertise is greatly appreciated! I've learned much more on these forums than anywhere else! Thank you all in advance.
 

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1. Larger injectors will need a retune, of course!
2. The stock Viggen IC is pretty crappy so you will probably not be able to use the full potential of the tune unless you upgrade your IC. But it's no problem running the Viggen IC for some time untill you save up for something better.
3. I don't think you'll need a new MAF.
 

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Discussion Starter · #3 ·
this is a great opportunity to educate the uneducated...(ME!) about why new injectors would require a retune. I have a slight inkling on why that is so but am not so sure if i'm 100% correct. so anyone please just jump in...

the better flowing injectors will provide more gas with the same electrical signal, so the engine will run mostly rich, right?

thanks again guys!:confused:
 

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SaabLV93 said:
this is a great opportunity to educate the uneducated...(ME!) about why new injectors would require a retune. I have a slight inkling on why that is so but am not so sure if i'm 100% correct. so anyone please just jump in...

the better flowing injectors will provide more gas with the same electrical signal, so the engine will run mostly rich, right?

thanks again guys!:confused:
Yessir. :)
 

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Your tune is set up to run "X" fuel pressure and "X" injector pulse width through the stock injectors, increase the capacity of the fuel injector without compensation in the software and you will be dumping fuel & running pig rich at WOT.

FYI - I'm sure there are more factors involved, but those are two that I am aware of. Let me know if you want to sell the green giants!

Mike
 

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the injectors will most likely run rich. the ic will be ok but you wont be able to cool the extra charge air so you wont see the full benifit of your new ecu. and the t5 b204l does not have a maf sensor only the t7 engines do. do you mean a map sensor ie a 3bar one for running higher boost?
 

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Discussion Starter · #7 ·
i have a t7. i just noticed that the maf for the S and SE were two different part numbers.

anyway...anyone here know the part numbers for the new oil and coolant lines i'm gonna need to install a td04? will i need to order all four new lines or can i re-use some existing ones? lemme know if you know! THANK you MUCH!
 

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Discussion Starter · #8 ·
Bigsky said:
Your tune is set up to run "X" fuel pressure and "X" injector pulse width through the stock injectors, increase the capacity of the fuel injector without compensation in the software and you will be dumping fuel & running pig rich at WOT.

FYI - I'm sure there are more factors involved, but those are two that I am aware of. Let me know if you want to sell the green giants!

Mike
so there's no other way the car monitors it's A/F ratio? it simply just 'trusts' the programming? is it theoretically possible, that if the car did somehow know whether or not it was running lean or rich, that it would have a compensation mechanism like allowing or reducing more air/boost?
 

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No, that's what an O2 sensor does, measures the remaining O2 after combustion. I'm assuming on a Saab that the ECU would reduce fuel pressure to compensate but don't know enough about the T5 or T7 to be sure.
 

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SaabLV93 said:
so there's no other way the car monitors it's A/F ratio? it simply just 'trusts' the programming? is it theoretically possible, that if the car did somehow know whether or not it was running lean or rich, that it would have a compensation mechanism like allowing or reducing more air/boost?
The ECU also monitors A/F via the O2 sensors, but very roughly, and primarily for emissions cleanliness.

It knows it's running rich or lean from the amount of airmass and the amount of fuel metered, which is why the injector size is so critical.
 

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Discussion Starter · #11 ·
Hey guys...i'm having a bit of trouble finding the P/N's for the lines i need to make the swap happen. anyone got them on hand? it would help, but i'm not in a real rush as i'm hella broke. my indy says he'll do the install 'on credit' but that's not my style....plus, how much are those new lines gonna cost? any help would be much appreciated. thanks again to all of you who are so supportive and responsive.

daryL
 

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With a narrowband O2 sensor you can only know that youre running lean stoich or rich not by how much. Your Ecu may know that its giving too much fuel but not how much extra fuel.
 

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Bigsky said:
No, that's what an O2 sensor does, measures the remaining O2 after combustion. I'm assuming on a Saab that the ECU would reduce fuel pressure to compensate but don't know enough about the T5 or T7 to be sure.
According to the WIS, T7 will both SLOWLY adapt to changes as much as 25% in injector size/flow through multiplicative adaption, and 4mg/combustion (a very small amount) through additive adaption. Hence why upgraded FPR's can still work even on stock motors, though it takes time for them to adapt.

The question is how much it has adapted already. You can check to some effect this with an OBDII scanner by looking for the "Long Term Fuel Trim". The closer to zero, the better.

Ergo, injectors sufficiently close to stock, or FPR significantly close to stock, will become a "learned" change in the system allowing for more fuel. But it takes time, so be gentle with the car for a few days before expecting it to have completely adapted.

-Adrian
 

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Discussion Starter · #14 ·
Adrian W said:
According to the WIS, T7 will both SLOWLY adapt to changes as much as 25% in injector size/flow through multiplicative adaption, and 4mg/combustion (a very small amount) through additive adaption. Hence why upgraded FPR's can still work even on stock motors, though it takes time for them to adapt.

The question is how much it has adapted already. You can check to some effect this with an OBDII scanner by looking for the "Long Term Fuel Trim". The closer to zero, the better.

Ergo, injectors sufficiently close to stock, or FPR significantly close to stock, will become a "learned" change in the system allowing for more fuel. But it takes time, so be gentle with the car for a few days before expecting it to have completely adapted.

-Adrian
with that said...the green giants are 42lb/hr. injectors, what about stock? my best guess is about 38lb/hr?
 
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