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Discussion Starter · #1 · (Edited)
Hey guys,

I have a mbc installed on my 1999 Saab 9-3 2.0. Usually when i floor it my car only boosts up to 18 psi but occasionally it goes up higher and I get fuel cut-off. What would be causing it to do this?
I just noticed that everyone talks about fuel cutoff being at 15.5 psi but mine has always cut off around 20. What would cause this?
 

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He has an mbc so he is essentially bypassing computer control. MBCs cause a boost spike due to the delay in getting pressure to the wastegate. The way to avoid this, for the most part, is to pre-load the line to the waste gate with some pressure. You do this by using an MBC with anticipator. Go to the smartperformance website for details.
 

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IMHO, I would definitely go with having a tune over the MBC. I had a MBC and liked the extra power it gave, but not limiting the boost in 1st was a little bit of a pain in how quickly it lights up the tires. Since I put a stage 2 tune in I am beyond blown away with the extra power above and beyond what the MBC gave.

I do agree though that an anticipator would help out tremendously with the overshoot.
 

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Discussion Starter · #5 · (Edited)
Ya I wanna get mine chipped eventually. The tire spin in first definitely makes off the line acceleration difficult. I'll need to get a new apc before I can chip it though. Is it worth it to convert to a t7 apc or should I just get a t5? I know the t7 is a lot cheaper but how much of a hassle is it to convert?
 

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Right before I put the t7 BPC on, I used the t5 BPC on a ecu I didn't modify yet. As for performance difference I don't see anything different. The biggest benefit I can tell is they are more reliable and cheaper.

You can pick one up for fairly cheap. There was one on here with the pigtail for like 30 bucks. I am contiplating selling my extra stage 2 ecu t7 BPC.
 

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Wiring it up isn't really hard. The t7 is two wires while the t5 is 3.

The harder part is the ecu has to be modified both hardware and software. You have to lift a pin of one of the IC's on the ecu and solder a bridge over two pads, then you have to change a few things in the tune to change the frequencies the e u uses to drive the BPC.
 
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