Why Fuel Cut!

[stratoayu]

this is starting to annoy me.. mods
3"ddp, test pipe, cat back, n1 muffler
custom hardpipes
k&n filter.
bosch bov

now before i had shims on my wastegate so it was hitting like 13.5 psi, and i said yea that makes sense for fuel cut.. so i took alll my shims out of my wastegate, and now i am hitting 10.5 psi.. but yet its still hitting fuel cut! i have done the trick witht he screw on the (stock) afm but i dont get it.. i should be able to hit more then that.. ive checked all my hoses and i dont think that i have a boost leak otherwise i dont think i would be able to hit 10.5 psi.. this is at like 3500 rpm or so in 3rd is when it usually hits... but i have had it in 2nd too.. the recirc hoses on my bov DO look like they r a little bit squashed.. would that cause it?? hopefully someone can help me

 

[NDBoost]

i was running 17psi on a 60-1 stock intake, stock injectors, 3" turbo back mandrel bent tubing. Never hit FC, now it seems if i hit 15lbs ill hit FC.. its gay im thinking about doing the screw mod.

 

[aye mate]

Double check for boost leaks. Check all IC piping connections and also the 3000 pipe -> TB connector.

 

[stratoayu]

wouldnt i be seeing a lot less boost and a lot later on in the rpm range if i had a leak? and a thing that was in the abck of my mind.. i think my turbo to downpipes gasket is a piece and is leaking.. but that would only cause creep would it not? and i would see that in my peak reading... and this is stock trim turbo. also i have a mustang o2 sensor.. and timing at 14..

 

[GrimJack]

I could still hit 12psi easy on my stock CT with a badly cracked coupler from the 3000 pipe to the throttle body.

I say boost leak.

 

[aye mate]

depends how big the leak is.

 

[lagged]

gotta say boost leak.

 

[stratoayu]

well shit, i am going to go buy all new clamps tomorrow... i cant really tighten down the stock shitty ones.. so ill just go buy some t bolt's and see what happens...

 

[PorterzSupra]

im gonna 4th the boost leak idea, happened to me a few times too, check 3000 coupling and rubber pipe where it hose clamps onto the bottom of the turbo, pull it off and inspect. If u still cant track it buy a leakdown tester from ebay so u can rule out leaks if you cannot find any visually. You turned the airflow meter screw counterclockwise all the way out right? You should not get BC till at least 15+

 

[Supracentral]

Be careful, it's not just clamps you need to look at.

I once had a boost leak that consisted of a hole the size of a freaking US Quarter that was like a little flap. At idle, it would pull the piece of rubber back into the hole an the hose would look 100% normal. Under boost it would blow wide open. It took me a week to find that little bastard, and that's the day I made my 1st set of hardpipes.

You need to check every piece of hose. Start from the turbo discharge and keep following the lines until you get back to the throttle body.

Put your hand on every line, feel around for cracks, especially "underneath" where you can't see them.

I'm 99% sure you've got a boost leak.

 

[stratoayu]

well i have a custom set of hardpipes.. removed the stock 3000 pipe.. so im guessing one of the clamps stripped getting put on and now isnt holding... im going to grab some regular hose clamps first... then if that doesnt work ill get some t bolts i guess... i only want to run like 13 psi... so regular clamps should work?

 

[boost fiend]

i run 11 psi daily on a ct 26. had a hks evc IV that let me hit 17 with the stock afm screw mod. never hit fuel cut till i lived in alabama for about 6 months. got back up here, issue went away. then i sold my ebc.

long story short, i agree with the group and say boost leak. either get a leak detector of take some carb cleaner to all the conections. double check everything.

and yes, at 10 psi, "worm clamps" SHOULD hold just fine. if their failry new.

 

[SP 7M]

this is starting to annoy me.. mods
3"ddp, test pipe, cat back, n1 muffler
custom hardpipes
k&n filter.
bosch bov

now before i had shims on my wastegate so it was hitting like 13.5 psi, and i said yea that makes sense for fuel cut.. so i took alll my shims out of my wastegate, and now i am hitting 10.5 psi.. but yet its still hitting fuel cut! i have done the trick witht he screw on the (stock) afm but i dont get it.. i should be able to hit more then that.. ive checked all my hoses and i dont think that i have a boost leak otherwise i dont think i would be able to hit 10.5 psi.. this is at like 3500 rpm or so in 3rd is when it usually hits... but i have had it in 2nd too.. the recirc hoses on my bov DO look like they r a little bit squashed.. would that cause it?? hopefully someone can help me

Your ECU may be causing you to run richer than necessary through its reaction to the BPUs you've added. The fuel cut changes according to A/F ratio. The richer the mixture, the earlier it hits...

I only read the first post, so if anybody else wrote this, I didn't copy you.

 

[PorterzSupra]

"The richer the mixture, the earlier it hits..."

Then why do 550 injectors help with fule cut, if anything they richen the mixture...

 

[stratoayu]

so do i just spray carb cleaner around the clamped areas and check for bubbles?? i just put on 2 brand new clamps on a spot where i thought it was leaking.. now its getting more boost faster... but then it hit fuel cut harder.... so i think i am getting closer to eliminating the leak...

 

[aye mate]

"The richer the mixture, the earlier it hits..."

Then why do 550 injectors help with fule cut, if anything they richen the mixture...

Who adds 550's with the stock AFM??? The 550s are there to compensate lost fuel when the LEX afm is added. The lex afm is added to LEAN the mixture out, the 550's are done to make sure it doesn't get too lean. Overall with the lex/550's you are keeping the AF ratio about the same just at different level, by adding more air(LEX) AND more fuel(550's)

 

[SP 7M]

"The richer the mixture, the earlier it hits..."

Then why do 550 injectors help with fule cut, if anything they richen the mixture...

Do me a favor and run 550s with the stock AFM. Report your findings when you've done that.

It may be in your best interest to get your facts straight before you jump to conclusions and make it seem as if I don't know what I'm talking about.

 

[mkIIIman089]

Are these silicone couplers you're using with the worm gear clamps? If so, ignoring the fact that I knew HTS specifically says DO NOT use them with silicone couplers; from my own experience with the cooleeze IC pipe kit the clamps will not hold and do loosen over time with silicone couplers. Nearly to the point of barely holding on. Possibly causing your potential boost leak to just crop up out of nowhere.

EDIT: On the fuel cut topic... its based on air flow, and has little or nothing to do with running lean. Although thats what its there to potect against, air flow is the only thing the ECU is watching to enguage it. So obviously thats why the Lexus AFM works, allowing more airflow to get by while the ECU recieves the same (as stock) signal.

 

[stratoayu]

no im using the stock rubber hoses as couplers

 

[mkIIIman089]

no im using the stock rubber hoses as couplers

Hrm, I think you should also check for vacuum leaks everywhere as well. Some times you'll hear them as they hiss pretty loud if they're big enough to cause a problem. I know specifically for me I had one on my Bosch BPV because the stock sized hose was too large to seal the smaller barb on the new BPV.