Hey guys,
Curious question for you cause I'm getting a boost conroler for christmas. I have hks up and down pipe 3" cat back exhaust what kind of boost can i run on my car before the fuel cut kicks in without hurting anything and what is factory boost level at? thanks guys

 

You might also want to invest in some sort of engine managment along with that. I believe 14 PSI is the stock boost level.

 

+1 or 2 psi, more is unsafe.

 

17 psi is fuel cutoff. i would get an electronic boost controller. Apexi makes a great one

 

Here's the quick and dirty version of why you shouldn't run an MBC- ever.

PTFB, Partial Throttle Full Boost. With an MBC controlling your wategate, you can get boost at low throttle openings, when the ECU is in closed loop fueling. The ECU doesn't realise you're in boost, so it's still trying to run lean A/F ratios for economy and emission. Lean + boost = high EGTs. This leads to detonation, preignition, and breakage of parts. So, if you want to run more boost, the best way is with real engine maangement that deals with these ssues like a Cobb AP or EcuTek reflash. EBCs have these same issues too, they're just more consistent and a bit safer in regards to preventing boost spikes.

 

Hrm, I wouldn't say "The ECU doesn't realize you're in boost". Its just that Open Loop Fueling doesn't kick in until you are past a certain throttle position. If you are below that threshold ("at partial throttle")and boost isn't controlled by your throttle but by an external boost controller, like an MBC, you can be stuck in Closed Loop Fueling but have high boost... and IIRC, CLF tries to maintain stoichiometric AFRs. This would be bad at higher boost, where you want much richer AFRs. I find this to be worst with MBCs.

fyi - CLF means target fueling based upon feedback from AFR readings. Its a "closed loop" - adjustments to fueling generate AFRs which in turn affect adjustments to fueling. OLF means that fueling is not based upon such feedback, but usually on pre-formulate values, like an underlying fuel map. So its an "open loop" - there's no relationship between sensor readings and fueling. This is why our stock O2 sensor sucks for tuning... it was only meant for feedback to achieve stoichometric AFRs while in CLF mode.

OK, its late. I'm bored

jason

 

All correct Jason. I have a hard time keeping OLF and CLF straight. Anyways, the issue is the ECU tries to run 14:1 AFRs under significant boost, which is bad.

 

SURGEON GENERAL'S WARNING: owning a TurboXS UTEC and Tuner can contribute to accellerated learning in regards to EMC tuning and has been known to turn generally normal people in huge nerds spewing off such terms as "Open Loop Fueling", "Closed Loop Boost" and, God forbid, "stoichiometric", whatever the heck that means.

 

You forgot the other part, where they don't learn fast enough and turn piston #4 into a charred lump of unidentifiable metal.

 

You're really making me want to go get a compression test *gulp*

 

Haha, if you had issues, you'd know about it already.