Under fuel cut = Safe ?

[Royalmaas]

Hi ! Im faairly new here as you can see, and im a happy owner of a 87`Supra :icon_bigg Lately i`ve been playing around with my boost controller to see if i can feel some difference in power at different settings.

Well what im trying to figure out is if my stock CT26 can handle around 0.8Bar/11.5Psi without beeing pushed to hard and reducing its life time drastically ?

Sense its my daily driver i would like to know if my car is not at it limits without me knowing:cry:

There are some minor mods to it:

Greddy Profec 2
2.5" No cat from Turbo and back
Open filter
MHG
ARP Studs
Everything else is basically stock


Atm i haven`t reached Fuel cut yet, but i was thinking i could just turn it up and see how far i can go before i reach it? All i realy want is to have a reliable car that is not being pushed to hard :nono:

I appreciate any comments, im still learning !

Cheers, Roy

 

[BoostMonger]

Fuel cut in your friend

Sent From My HTC One S using Tapatalk 2

 

[gsxr141]

looks like everyone but me can go past 8psi without hitting fuel cut.
looks like the greddy profec is going in today to replace the $2 boost controller that came with the car. lol

 

[BoostMonger]

looks like everyone but me can go past 8psi without hitting fuel cut.
looks like the greddy profec is going in today to replace the $2 boost controller that came with the car. lol

Don't be sad Gixxer. Maybe you have a boost leak?

Sent From My HTC One S using Tapatalk 2

 

[gsxr141]

i had one, but fixed it. i have 2.5" intercooler piping now. i guess my car is just finicky. it will hit fuel cut when shifting into 2nd at high rpm, and sometimes when going towards the higher range on the tach. it's very intermittent.

 

[radiod]

After you fixed your initial boost leak did you try checking again? Did you use a DIY boost leak tester? Are there any other codes flagged other than 34? Something else is likely going on if it's still cutting that low. Lowest I've seen legitimately cutting is around 10 - 10.5psi and that was everything going against it (sea level, winter time, etc).

 

[gsxr141]

when i had the leak it was at or under 5lbs. that issue is gone with the new piping on there. the fuel cut has been around 10 ever since i've owned the car. i'm hoping it's just a shitty boost controller. the car is great in first gear, but as soon as i shift into second it hesitates, then goes.

 

[jonahs_supra]

to answer the OP question
most supras can run 11.5psi w/o hitting fuel cut

fuel cut isnt determined by how much boost you run...its how much air is pulled through the afm...air density now plays a role in this
fuel cut happens when the HZ signal from the afm to the TCCS(ecu) reaches 1400hz
now depending on air density you could fuel cut at 10psi or 14psi
also boost leaks will cause fuel cut
when the afm reads lets say 10psi of air and you have a boost leak that bleeds off 2psi of air
the wastegate in the turbo closes again to add the extra 2psi of set boost pressure
so now the afm is reading 12psi worth of air passing through it...thus hitting fuel cut(depending on air density)

you can put a bigger turbo on your car and run lower boost lets say 8 psi and still hit fuel cut due to how much air its sucking in through the afm

do you understand?
thought i would share a little knowledge

 

[3p141592654]

You are correct that fuel cut is set by the amount of air pulled through the engine, but it is not clamped to a specific frequency from the AFM. Rather it is clamped to a maximum computed load value which includes air flow, intake air temperature, and air pressure, and rpm. For the stock ECU, fuel cut triggers at 78% of full-scale of the computed load variable.

 

[jonahs_supra]

You are correct that fuel cut is set by the amount of air pulled through the engine, but it is not clamped to a specific frequency from the AFM. Rather it is clamped to a maximum computed load value which includes air flow, intake air temperature, and air pressure, and rpm. For the stock ECU, fuel cut triggers at 78% of full-scale of the computed load variable.

thanks for the info

 

[Royalmaas]

Wow, Thanks for the help guys !

Tried to run 1Bar/14Psi but it was still not fuel cutting, so atm im just riding on 12Psi to be on the safe side.