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Discussion Starter #1
People here running a MBC can please share your knowledge?

- How have you hooked it up? Between BPC and wastegate or straight from compressor to wastegate?
- Any specific brand or type we need to use? I heard about SMBC but not sure what's the difference
- How much boost to set for a stock Aero (and how)?

Thanks

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There's a world of knowledge on here and none of it falls into the usual caveat for 'OH, this is a turbocharged car!': CAI, BOV, crank the boost up!

Tune Tune Tune. No better bang for your buck improvement over stock power, and the only safe way to adjust boost. If you're after a BOV sound, pony up for an aftermarket diverter valve and open-air filter.
 

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People here running a MBC can please share your knowledge?

- How have you hooked it up? Between BPC and wastegate or straight from compressor to wastegate?
- Any specific brand or type we need to use? I heard about SMBC but not sure what's the difference
- How much boost to set for a stock Aero (and how)?

Thanks

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What are your power goals. The stock ecu can handle as much power as you want realistically. "boost" is already controlled by Trionic. No need to reinvent the wheel.
 

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Discussion Starter #6
This is the history of the matter:
Hi guys, I've been troubleshooting a boost problem in 2002 9-3 Aero with no luck. I thought I'd post here for more opinions as it's the same T7 system.
Car runs well except it only boost to mid yellow maximum. I've swapped out/ cleaned/ replaced/ checked following so far,
- BPC valve
- Wastegate
- MAF
- DI cassette and plugs
- replaced vacuum lines
- checked intercooler hoses
- Bolt mod
- Bypassed vacuum valve on the firewall
It seems ECU is limiting the boost for some reason. No error codes.
RUNS AS IT SHOULD (or even better) WHEN WASTE GATE VACUUM LINE IS DISCONNECTED. Boosts up to mid red and fuel cut (what a fun drive that was!).
I read a thread where someone had eliminated the waste gate vacuum line and capped the BPC and waste gate end, but that thread was inconclusive. Any suggestion is much appreciated..

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This is the history of the matter:
Hi guys, I've been troubleshooting a boost problem in 2002 9-3 Aero with no luck. I thought I'd post here for more opinions as it's the same T7 system.
Car runs well except it only boost to mid yellow maximum. I've swapped out/ cleaned/ replaced/ checked following so far,
- BPC valve
- Wastegate
- MAF
- DI cassette and plugs
- replaced vacuum lines
- checked intercooler hoses
- Bolt mod
- Bypassed vacuum valve on the firewall
It seems ECU is limiting the boost for some reason. No error codes.
RUNS AS IT SHOULD (or even better) WHEN WASTE GATE VACUUM LINE IS DISCONNECTED. Boosts up to mid red and fuel cut (what a fun drive that was!).
I read a thread where someone had eliminated the waste gate vacuum line and capped the BPC and waste gate end, but that thread was inconclusive. Any suggestion is much appreciated..

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Maybe check fuel pressure? It's possible that the ECU is detecting knock or misfires and is limiting the air request. Are you on the stock tune?
 

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Discussion Starter #8
Yes on stock tune. No misfires recorded and running on premium fuel

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Discussion Starter #10
I does go to at least to the top end of yellow in my experience

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The "boost gauge" on the dash is controlled by the ECM. There is actually a setting in the tune you can change to make it read what you want. You need a real boost gauge to see actual boost. You could also enable open SID. Pinl is pressure in bar (you would need to convert to psi).

Jay
 

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Discussion Starter #12
Yeah I've ordered a boost gauge as well. But I can feel it. With the boost the accelerator pedal feels "heavy". This one drives like a n/a car

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Dont install an MBC, it will do much more harm than good
^^^^click. Forums give excellent advice lately. Much needed, fresh influx of new owners all ready to (with respect) re invent the wheel. They need good info. But clearly they have to be prepared to listen to the advice and remove the junk non oem stuff they have put on the car.
 

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Discussion Starter #15
Car was running around 6 psi. Fitted MBC between BPC and wastegate. Set around 11psi. So far no issues. Even tried around 15 psi and got no cel or anything. I just wanted to see what happens since it was an easy thing to test/ try. I'll probably will take it off before it blow up the engine or turbo or both. Thanks for the advices guys. Much appreciated. Probably you guys have tried all these decades ago and say things from experience. But this was the only thing that sorted the boost issue I had

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Gonna resurrect this since I am the new owner of DAVID IN TALLAHASSEE'S SAAB 900. From reading all of his posts I have deducted you will want both a MBC and an adjustable wastegate actuator. This is so you can set the wastegate to 7-9 psi and then have the MBC take you to right below the cutoff which is about just over 15 psi. Have both adjusted properly will allow you to have max boost with out as much spike.



Note: since I realize this may be the connector post from when david last had it and when its in the hands of a new owner. Let me tell you the issues i have had getting this car on the road. I had new axles installed 3 times because 2 of them fell out with in a week. Ended up having to put the stock suspension back on the front to stop the axel from sitting sideways. Guess over time it just killed the mount/frame so the axel was way off 20+ years later lol. Then after that had to replace the mounts like 2 times because the first or second axel bust broke them all again. Then after that I had a coolant leak, replaced all the tubes and then belt snap because the modified air intake moved and hit the belt. Im getting a cel now because I guess the o2-simulator he used is finally dying... i may order a new one and just put back in original spot. Ive since modified the convertible to be manual and the car seems to be doing good. I have an exhaust manifold leak but already ordered a new manifold.. I noticed he ported his old one but later said porting does no good so Im hoping I dont have to port this one. Thank you David for being so knowledgeable.
 

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Gonna resurrect this since I am the new owner of DAVID IN TALLAHASSEE'S SAAB 900. From reading all of his posts I have deducted you will want both a MBC and an adjustable wastegate actuator. This is so you can set the wastegate to 7-9 psi and then have the MBC take you to right below the cutoff which is about just over 15 psi. Have both adjusted properly will allow you to have max boost with out as much spike.
Is that his T28 turbo? its a T5 car Its tuned to max, using an MBC is worthless for his and ofr these cars. The ECU is very complicated and any input (like an MBC) is adjsuted for/against, so dpnt; waste your time
 

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Yes, this is exactly what he used to achieve that. He disabled the MBC and set the wastegate actuator to 9-10 psi for his daughter. I simply found all his threads and found out how he set it up and got it going at about 25psi. He was doing his 29+ psi setup by having the wastegate actuator at 18psi and using the MBC to get the rest. You can tune the ECU or you can take the other approach. From what I read he used a lot of his old porsche knowledge to keep things manual/no computer changes.

search MBC+A – The Anticipator. Premise, Instructions, and Setup for how to set it up.. he mentions using it in the thread titled "do i need to preload the wastegate actuator??"

Sorry cant post links yet so I can just give data to search.


Btw I came back to say this car is ridiculous. I had to set it back to 15psi case it was just too much.
 
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