My car has the following mods, TBE (testpipe), intake, tune for 21psi.

Car runs great in 1st, 2nd,3rd, but on a highway when I WOT at a lower RPM (4.5k) in 4th, I get boost creep up to 24.5 psi. Then at 5.5k rpm, the whole car just cuts off, backfire, rpm drop. I was told that is a safety thing because I'm boosting too much. (sorry I forgot the real name of what that is called ^ )

The weather here has been around 0 degrees for the last week or so, and from what read, boost creep accours more when it's called outside.

To eliminate my problem, I should get the wastegate ported. While I'm doing this, should I get a Megan 02 housing as well? From what I read, cars with 02 housings are more at risk to have boost creep. So this is where I'm confused.

 

Its called boost cut. Who did your tune and how is your boost being controlled?

 

I thought it was called fuel cut.

I would suspect that boost is being controlled by a manual boost controller. This is common for MBC's and cheap EBC's that can't control spikes when the weather changes.

 

If you have a decent MBC like a Hallman or a Forge, you shouldn't get the creeping problem. Also, the tune should have tuned out the cut.

 

Just to clarify, it is fuel cut, but it happens when you hit a certain amount of boost (overboost). Colder air=a more dense charge so you will get a little creep when its colder. I just turn down my MBC accordingly.

 

Yes, fuel cut, that's the name. Sorry everyone, I'm learning...

The MBC I'm using is an older AMS one. My car was tuned by Adam at Devo tuning. I know none of you guys know who he is, he is not active on Evom. But he specializes in Evos and DSMs, and builds alot of monsters. He knows his stuff.

The reason the cut was not tuned out is because I should not be holding boost at 24.5 psi.

I wonder if I should just upgrade the boost controller and call it a day. $100 compared to about $380 (megan 02 housing/ porting wastegate and labor)

 

Just turn down the boost. Does your boost spike to 24.5 or actually hit 21 and slowly creep to 24.5psi?

 

turn the mbc down to 21 psi

 

The first 3 gears hit and stay at 21 psi. If I start from 1st and to a pull through all the gears the car runs great, no cut off.

But when I do a pull in 4th gear only, start at about 4.5k, that is when it hits about 22 and goes to 24/25 psi. I think its creeping there, I guess I will check it out again today on my way home.

If I turn down the boost controller, then I'm no longer going to hit 21 and stay there. I guess I can do that until it gets warmer and see what happend then.

 

Get a fuel pump and some bigger injectors.

 

got a pm.

 

i am having the same problem in md man. excepty 4k in 2nd all the way through beginning of 4th. i tryed turning the perrin manual boost controller down and it seemed to work a little better still one backfire but better then 3-4 at WOT

 

I think fuel cut shouldn't be tuned out because it's one of the ECU's safety feature, especially if you're running street gas. As for the MBC spiking / creeping: This is why I prefer EBC's. The good ones are always consistent and can make a much flatter pressure throughout the RPM range. MBC's "get the job done" but you usually have to do a lot more to the ECU's maps to compensate for the MBC's behavior.

 

So should I experiment with a different mbc? Or just get the o2 housing and w/g ported... anyone local (chicago) that is willing to let me borrow their better mbc?

 

Not a different MBC. Try an EBC. A ported O2 housing might help with creep a bit, but a good EBC will be your ticket (HKS EVC 5 / 6 or an APEXi AVC-R).