Well this weekend, i got my car on the dyno and got tuned up as well while I was there. The tuners wanted to go 21-22psi on my car, but unfortunately my car kept hitting boost cut on anything over 20. So we kept it there, and kept my afc on the conservative side as well. Well today its raining outside and my car has been fine after this weekends tune until today when it started raining out all day. I hit boost cut around 4500rpm. I have walbro 255lph HP pump, apexi power intake filter kit, hallman mbc set at 20, type S, full exhaust, SAFCII tuned on wideband at dyno, HKS 272's and AEM cam gears set at -4 on each. I think because its raining out and keeping my intercooler kool, that im hitting boost/fuel cut. My question is how can I avoid this without turning my boost down so I can keep it set and keep the same WHP that I am tuned for without hitting boost cut?? Yes, I have a boost gauge and it doesnt look to be going over 20psi at all either. Is there more parts I need besides a different form of managment to help on this issue, because im going to keep my boost set for where my car was tuned for.

 

what do you mean by boost cut? is there a popping sound? Check your hoses be sure there are no tares.

and if you have ebc check to make sure you T'd the right hose.

 

I have the same exact problem, my modds are very similar to yours. I can bet you that once you take the intake out you will not have anymore problems. I still can't find a way to bypass this issue with fuel cut, but i was told larger injectors might help and some flashes can raise or eleminate FC, but I'm getting a standalone to eleminate the maf. Good luck.

 

kool deal...yeah it sucks, but i didnt think our cars cut until like 22psi or so?? hmmm

 

You can hit at 20 PSI or even lower depends on the weather and the car. Going with the larger fuel pump and injectors can cure it.

 

i already have the HP 255lph walbro

 

get bigger fuel injectors

you'll need to retune it though
you could possibly make more power too with bigger injectors

 

Same thing happens to me when it is cold out, I usually boost a little over 20psi. Once the temps dip into the 50's and I hit about 5k rpms I will hit fuel cut and throw a CEL. It sucks and I am waiting to get tuned to cure this.

 

If you have the 255lph fuel pump you need bigger injectors to avoid fuel cut. At times I hit 24-25psi and no fuel cut. Just a tune will not help cure this.

 

Question: What exactly triggers boost cut? Is it a detonation signature flagged by the knock sensor?

 

It happens at 1700 Hz Karman value at 20°C and 1000 mbar athmospheric pressure approx. That is roughly 1.2 bars relative boost. We will see more of these post as fall arrives. Also, make sure you have the supporting mods if you bypass the fuel cut safey feature. You'll know when you hit it as it feels a like you hit brick wall for a second. Fuel and spark are cut instantly at the trigger.


Speedlimit..

 

The preset ECU perameters..
93civEJ1, what you are experiencing is a result of the cooler weather, we were quite close to this threshold on the dyno I did mention this could be a problem when it got colder...re- installing the stock airbox may reduce these symptoms. This is another reason why you need something more than the AFC... can I talk you into an Xede/Xedeflash now?

 

The Emanage is another tool to get rid of the fuel cut prob, kind of detailed, but easy to work with once you figure it out

 

Ad another vote for weather change.

I guess an instant way to prevent it, is to turn down the boost a bit.

 

Thanks, good info.

I'm getting the Xede and Xede flash (fixes boost cut) with my setup, but I'm simultaneously upgrading to 255lph and 650cc injectors to deal with it. I've ordered that to go with a Vishnu Stg 1 and HKS 272s.

Also, here's a thought...

If one uses long duration cams and no gears to dial out some of the overlap, I suspect some of the metered fuel charge is going 'out the window', which at some point would result in detonation. I seem to recall someone reporting fewer recorded incidences of detonation after going to the -1/-4 cam timing with the 272s. I suspect the 272s are on the fringe for typical street apps, and I am going to follow suit by taking out some overlap when I get them installed.