Fuel Cut Defenders- Their Limitations?

[Pr0j3kt_SuPrA]

hi everyone im sorri if this has been covered but i suppose id like to know the limitations with using a FCD. i understand they modify the signal the ecu gets thus trickin the computer into thinkin its under the fuel cut boost level. but the computer would still be injecting the same amount of fuel even though there is more air thus creating a lean mix situation

correct me if i am wrong but that how i understand it works?

so my question is how much boost can i use above the fuel cut limit before im in danger of damage.

i have a 1jz motor if that helps

Any help/hints and advice appreciated

Mo

[PlacentaJuan]

lol when i read your writing its sounds like you have a cockney accent.

i think the only safe way to tell how much boost is safe, and therefore if you have a safe a/f ration is to take it to a dyno.

otherwise i was running an extra 4psi on my 1jz with no worries and an extra 4psi was a lot more power!

[Pr0j3kt_SuPrA]

lol a cockney accent??

well recently installed dump pipes on the car and had a "cat" replacement has that much more flow it hits boost cut in all gears

so im assuming 1jz's have 10psi stock... u had 14psi total?

[PlacentaJuan]

yea 14psi and the car has been run reguarly at more than that for a few years.

if your boost is going up as a result of exhaust, intercooler, or climate change (rather than with a boost controller) you should be fine chucking in a homemade fcd, i wouldnt even bother getting dyno or a/f ratios unless you were going to serisouly turn up the boost manually.

go for it the 1j will love you.

[Pr0j3kt_SuPrA]

yeh well i suppose i wanted to know the magic number as to when i should start looking at a SAFC or sumthing in essence i dont wanna break my motor as i know u can do with lean mixtures. i was running 14psi on high boost before the dumps but have removed the MBC 4 now

[Officer Doofy]

the mighty 1j should hit boost cut at around 14psi or 4.32v
If you want to run more boost than that i would use a fcd that you can set the clamp voltage for. 4v clamp will be ok for up to say 15psi, raise the clamp voltage to as close to fuel cut for anything higher.
I think ribfeast on here runs 18psi through standard ecu with ok afr with around a 4v clamp.

Have a search lots of info, most has been covered, including map sensor voltage outputs/
boost levels.

[Pr0j3kt_SuPrA]

cool thanks guys... so i turn the dial on the HKS FCD to 4? i suppose its had since all of it is jap lol well yeh i should be running less that 18 psi i hope