hmm need help,. hitting fuel cut at STOCK Boost levels

[Nihiliz]

7m is fully built. hks 2mm hg,. etc. stock everything else. minus boost controller set at the stock 6 psi. till i do future supporting mods like a smart cookie ,. anyways,. latly its been hitting fuel cut going up hill etc. and now today its horrible,. im only building like 4 psi,. turbo is fine. i went over all the vac lines,. and tighted the clamps down for the ic/piping,. but i did notice a exhaust leak near the Elbow, would this exhaust leak cause that,. or would you still think its a boost leak,. please help. kinda need my car tomorrow,. and yeah its very important hah,. help please!!

 

[ben1984j]

Yeah, that exhaust leak needs to be fixed first.

 

[Kevin]

are you sure its fuel cut? are you getting code?
do you have stock turbo?
an exhaust leak near the elbow shouldnt cause fuel cut..

 

[Nihiliz]

yeah everything is 100% stock minus built 7m/r154/driveline,. and turns out the exhaut gasket from the turbo to the elbow is shot,. you can feel air coming from that,. so yeah i think that should def cause fuelcut. and im positive its fuel cut,. this is the 5th Supra i have owned.

 

[Kevin]

i dont understand how that causes fuel cut.. when exhaust has nothing to do with it. fuel cut is dependent on the air flow meter.. when too much air comes the afm reads it up to a certain frequency (cant remember off the top of my head what it was)but then the ecu see's it and cuts the fuel.

 

[Fubar231]

^^ I believe its somewhere around 1500hz

 

[GrimJack]

A leak in the exhaust will not cause FC.

FC is virtually always caused by a boost leak. If you're stock everything outside the engine, chances are you have a cracked intercooler pipe or a split coupler.

 

[Fubar231]

^^ This.

Build yourself a boost leak tester and double check for yourself.

 

[Nihiliz]

update checked everything,. everything i 100%. minus exhaust leak,. and car will only push 2lbs of boost,. no shaft play,. stock turbo is fresh. and hits fuel cut now at 3 psi.

 

[Kevin]

and you're only getting the overboost code?

 

[dubsupra209]

cracked ic pipping...?

 

[Kevin]

there is definately a problem either ic pipes or bad afm?

no way the only problem u have is the exhaust leak

 

[Nihiliz]

yeah,.

 

[Nihiliz]

yeah i just dont understand it,. like. when this all started,. i was driving it normal,. like, having a little bit of fun,. than drove it home,. and let it idle cuz i dont have a turbo timer,. and shut it off,. next day,. start her up,. let her warm up and went to "joy ride" and yup!. lol this nightmare started.

 

[Kevin]

weird.. and u didnt change anything?
if you check everything we told you to check i have no idea.. someone else smarter than me should chime in eventually lol

 

[Nihiliz]

lol,. only thing i changed before i drove it,. was taking the dust of the dash and windexing the windows, and cleaning the rims making her purrrrty

 

[dubsupra209]

lol,. only thing i changed before i drove it,. was taking the dust of the dash and windexing the windows, and cleaning the rims making her purrrrty

have you checked the inside of your ic pipes cause if there cracks in there im pretty sure its a boost leak not a expert but this same problem happened to my friend....what codes are you getting..?

 

[Nihiliz]

ive checked everything hehe,. had a nice wonderful day out,. as for codes i dont know how to read them,. i searched earlyer to learn how to read them,. and i have adhd,. and yeah i just cant learn how to do it,. someone has to show me,. ;/

 

[ben1984j]

Are you guys sure his exhaust leak won't cause this?

http://www.supramania.com/forums/sh...ing-fuel-cut&p=1464001&viewfull=1#post1464001

It's not just any exhaust leak, it's an exhaust leak between the turbo and downpipe. Wouldn't that essentially act like a boost leak? Those exhaust gases should be helping spool the turbine, but they're not. And when you have metered air escaping after the throttle body, more air needs to pass through the AFM to maintain any given boost pressure, causing you to hit fuel cut earlier (at lower boost). Please correct me if any of that is wrong. Edit: Yup, it's pretty much all wrong...see later post.

And here's how you check codes. http://www.cygnusx1.net/supra/TechTips/engine_error_codes.aspx

 

[supradjza80]

Are you guys sure his exhaust leak won't cause this?

http://www.supramania.com/forums/sh...ing-fuel-cut&p=1464001&viewfull=1#post1464001

It's not just any exhaust leak, it's an exhaust leak between the turbo and downpipe. Wouldn't that essentially act like a boost leak? Those exhaust gases should be helping spool the turbine, but they're not. And when you have metered air escaping after the throttle body, more air needs to pass through the AFM to maintain any given boost pressure, causing you to hit fuel cut earlier (at lower boost). Please correct me if any of that is wrong.

Edit: And here's how you check codes. http://www.cygnusx1.net/supra/TechTips/engine_error_codes.aspx

yes we are sure the exhaust leak is not causing FC