is i possible to hit fuel cut at 10 pounds boost?

[chefma70]

i have a freshly rebuilt 7m with a stock ct26.

but the motor has alot of the basic bpu mods.

i have full turbo back 3inch exhaust,k&n intake,greddy bov,3inch in and out intercooler with full 2.5 inch piping.my waste gate is shimmed so im at 10lbs of boost. i actually dident shim my wastegate i bought the ct26 like that.

if i dident list it,it is still stock.

with these mods should i be hitting fuel cut?

 

[jdub]

No...check for boost leaks.

 

[suprajztwenty]

stock boost gauge? looks like youre just above 8 right? with 2 shims i stay under fc, but with that 3rd washer she pulled excellent untill about 5k and cut out. dont know exactly what the boost was (still have the stock gauge) but i think the tsrm manual says 12-14psi

obviously fuel cut isnt a good thing, even for a fresh motor (mine has around 30k on the rebuild with hks 1.2 mhg and arp's) but after the 2nd time i hit fc i was done messing around and took them back out....besides shimming the wg will stretch the spring and weaken it. id just go to home depot and do a manual controller once you fight the fuel cut (my plan for now anyways)

once i get my boost gauge, wideband, safc2 and ic piping ill go with the 57trim and crank it up. honestly i dont know how to get rid of fuel cut, never searched it...but as long as you have some mods like above then id def look into it and turn up the boost!

 

[chefma70]

No...check for boost leaks.

i hope i dont ge flamed for this but...

what would make boost leaks what should i be checking for??????:1zhelp:

i can tell you that the place where the turbo elbow and down pipe meet dosent have a gasket doest that count as a boost leak.or is boost leak something to do with vacume lines??

my boost gauge reads a steady 22 at idle is that normal??

 

[TurboStreetCar]

Fuel cut at 10 psi is not uncommon, I was hitting it slightly above 10 psi. Many factors other then boost are used to reach the threshold of fuel cut.

Boost leaks are anywhere from compressor housing to throttle body, or anything in the intake tract like vacuum lines.

Before modding your car any further, research this forum in as complete entirety as possible. If you blindly modify this car, it most likely wont be tolerated for very long.

suprajz20: Fuel cut is a good thing, without it the amount of blown engines would quadruple. Fuel cut cannot be eliminated as long as the stock TCCS (ECU) is being used. Its a safety feature (a very good one) that will save your motor if you have a wastegate malfunction.

 

[jdub]

Fuel cut is determined by one thing and one thing only - the volume of air sensed by the AFM. That volume is affected by air density - a colder OAT will cause it to occur earlier. If you have a leak in any of your IC piping, the volume passing the AFM will be more than the motor is using. Thus you will hit fuel cut early.

Vac reading guide:
http://www.cygnusx1.net/supra/TechTips/vacuum_gauge_readings.aspx

 

[mdr40z]

real common, this is why God invented 550's/lex

 

[suprajztwenty]

THANKS jdub!!! i never knew THATS why people use the lex afm, i always thought it was just for more volume to help the system breathe...only had the car a few weeks now, havnt gotten around to searching much yet...sorry.

 

[MKIIISupraGuy]

i hope i dont ge flamed for this but...

what would make boost leaks what should i be checking for??????:1zhelp:

i can tell you that the place where the turbo elbow and down pipe meet dosent have a gasket doest that count as a boost leak.or is boost leak something to do with vacume lines??

my boost gauge reads a steady 22 at idle is that normal??

mine sits at 19

 

[Hmong_1G]

Other way of running 10psi without fuel cut is to extract the screw out in the blocked off passageway. This is the same theory with the LEX AFM as It will allow enough air pass the AFM to be undetected.

First but not least.. check for boost leaks, fuel cut is GOOD, maintenance.

 

[supramk3]

I was hitting fuel cut at 14 and i have an t3t4 garret turbo and the only thing i can say to solve all the problems u will have is to go stand alone or waste 500 bucks on things like safc and others parts that only give u 17 to 20 more hp and a lil tq when u can tune ur car all u want and mess around with boost pressure fuel pressure and all the secret ingredents to make a sick mk3

 

[TurboStreetCar]

I was hitting fuel cut at 14 and i have an t3t4 garret turbo and the only thing i can say to solve all the problems u will have is to go stand alone or waste 500 bucks on things like safc and others parts that only give u 17 to 20 more hp and a lil tq when u can tune ur car all u want and mess around with boost pressure fuel pressure and all the secret ingredents to make a sick mk3

A lex afm, bigger injectors, good fuel pressure regulator and an safc is capable of a very good amount of power. I remember seeing someone recently breaking 500 to the tire. A standalone isnt the only "fix".

Not saying its the safest/best, but capable.

 

[jdub]

I was hitting fuel cut at 14 and i have an t3t4 garret turbo and the only thing i can say to solve all the problems u will have is to go stand alone or waste 500 bucks on things like safc and others parts that only give u 17 to 20 more hp and a lil tq when u can tune ur car all u want and mess around with boost pressure fuel pressure and all the secret ingredents to make a sick mk3

:nono:

 

[just90gs]

you can check for boost leak's with a simple tool all you need is a cuppler the size of your turbo.too hose clamp's a pvc block off and a air valve stem.
Then you take that pvc block off putt it in the cuppler put the 2 hose clampes on the cupple and the valve stem on the the block off.
And you now have a tool for checking boost leak's.

 

[whitemike]

:nono:

Right? Jesus..

 

[mdr40z]

I was hitting fuel cut at 14 and i have an t3t4 garret turbo and the only thing i can say to solve all the problems u will have is to go stand alone or waste 500 bucks on things like safc and others parts that only give u 17 to 20 more hp and a lil tq when u can tune ur car all u want and mess around with boost pressure fuel pressure and all the secret ingredents to make a sick mk3

 

[chefma70]

lol

 

[suprajztwenty]

so whats a rough estimate what kindve boost you can peak with a lex afm before cut? is 400 to the wheels using an safc2 going to be possible...or even worth the time trying?

 

[mdr40z]

so whats a rough estimate what kindve boost you can peak with a lex afm before cut? is 400 to the wheels using an safc2 going to be possible...or even worth the time trying?

can't do it with a stock CT, that's about tops with 57 or 60 trim CT with other supporting mods (ie, fuel upgrades), with properly matched T4 turbo 500+ with appropriate supporting mods, research this site and others. there is tons of info out there
Gotta pay to play tho
Find the informative links at the top of the page for more like:
http://rob.carlile.home.mchsi.com/lexus/lexus1.htm

 

[suprajztwenty]

can't do it with a stock CT, that's about tops with 57 or 60 trim CT with other supporting mods (ie, fuel upgrades), with properly matched T4 turbo 500+ with appropriate supporting mods, research this site and others. there is tons of info out there
Gotta pay to play tho

well yea i figured that was a given, sorry...driftmotion 57trim eventually. ive done a little searching, and i figure the combo ill need but most people seem to be running maft pro, will an safc do just fine for 400whp?