The Limit of our ecu's and Fuel Maps Options

[Island_Racer]

Hey guys,
My boost cut is set at 12 PSI, the standard that we all know about, but i have an emanage blue running and wonder if i simply remove boost cut whether or not the ecu can manage the limit of 17psi without any additional tuning (not that im not intending to) just not at the moment.

Any advice on the limit of our ecu?

[SupraKid]

You have a gt4 im going to assume? And by "boost cut" do you mean fuel cut? And if so fuel cut it there for a reason, if you just bypass it you will end up hurting the engine.

[Island_Racer]

ye, i kno, but my question is, does the ecu have a decent map programmed in to support the boost to say 17psi (closed loop functioning)....like if i was to set the fuel cut at 19 psi and boost to 17 using a controller wud the car be able to function somewhat fine (not in harm). Or do i HAVE TO get it tuned the same time that i move the fuel cut.

This post has been edited by Island_Racer: Jun 16, 2011 - 5:46 PM

[SupraKid]

Are you using the greddy emanage or the stock ecu?

[Island_Racer]

Are you using the greddy emanage or the stock ecu?

the greddy emanage is a piggy back....alone it cant do anything, it has to be used with the ecu.
I dunno if you get what im asking. I just wanna know how many psi the ecu closed loop function is tuned to.
Id personally of guessed that toyota tuned it to the limit of the turbo (~17psi) and just curious if anyone knows
already and can gimmie some pointers before i move the cut and find out myself. i guess it wud be easy to just
add fuel and have it run rich but this is just an info seeking thing.

This post has been edited by Island_Racer: Jun 16, 2011 - 7:21 PM

[SupraKid]

hmm for some reason i always thought the emanage was a standalone. I would recommend posting on gt4oc as most of the celica owners on this site are not gt4 owners.

[delusionz]

what 3sgte??

gen 2 is mapped to about 14 and gen 3 is mapped to about 17, its safe to run just before cutoff point, the only problem is when running so close to cut off that boost spike can easily trigger, but with gen 3 it would be safe to raise the cut to around 18 or 19psi while clamped on to 17psi fuelling aslong as you always run high octane fuel, and up to around 20psi with water.

[3WayStunna]

EDIT: also just to answer your question as to what would happen if you circumvent boost cut. No, the only map the ECU "uses" to account for anything above 1.1 bar is to run extremely rich (85-100% duty cycle) . The end, point and blank. That is why you see alot of ppl using water injection these days with the 3sgte. (aside from its usual benefits). Its to account for higher chances of detonation that WILL happen under normal circumstances when you run your injectors at that high of a duty cycle. Not to mention what it could do to your injectors and fuel pump over time even if you do choose to move to something incredibly higher than 1.1 bar.

So in short, while using race gas, and water injection to make things SAFE, its really not that smart if you can just save some money and get a proper ECU and Fueling Setup, which i will mention later.

Dont forget that while you say .09 bar is the accepted thought, boost is still limited to .05bar in 1st and second gear, .09 bar in all others (REV3).

Basically that is your boost limit with the 3rd gen. Only way to raise it to 1.1 (accepted safe for those without some sort of knock control) is either with a manual or electronic boost controller. Id recommend the electronic though. To go past that without resorting to another Aftermarket ECU, would be to use an active map clamp (make your own, or buy a 100usd HKS unit) and hopefully do whatever possible to reduce chances of knock within your engine (use water injection, LAG your chargecooler are just some of the most common methods used in conjunction with each other).

Other than that, other limits include a speed limit of up too 191km an hour. Best way around that is with a speed cut device.
You also have your REV limit which is 7250rpm.

Other limits, not just with an ECU are with the fuel pump. Its rated at 210lph. And while your injectors are rated at 540cc's at 36psi ( normal operating range for the 3rd gen 3sgte) you can raise the pressure as well with an aftermarket FPR to pump out more fuel, along with an addition of a higher rated fuel pump(walhbro/aeromotive/supra), though usually not recommenmended.

Those are the usual limits dealing with the electronic side of the 3rd gen 3sgte.

My opinion/advice. Save up your money and get an aftermarket ECU. After adding all the things you will need to get your 3sgte running at 1.1-1.5 bar, you would have added alot of stuff and cut into alot of wires. AND no matter how neat and clean you make it all look its rather GHETTO, when compared to just saving up a few hundred bucks and getting a proper ECU, injectors, and fuel pump.

These days there are a TON, i mean literally tons of options and resources at your disposal to do things, cheap, right......... BOTH. My upcoming setups in the future will be using 550cc injectors, an aeromotive fuel pump, and a megasuirt ECU. All of this would cost me around 500-600usd and would be a proper setup that will help me run my engine at around 1.2-1.4psi SAFELY....Hate to say it, but the greddy emanage BLUE is garbage.

This post has been edited by 3WayStunna: Jun 17, 2011 - 5:12 AM

[ST205WRC]

3waystunna is completely right about everything except the the boost in gears. 1st gear is .7 bar (11 psi), 2nd and up is .9 bar (13 psi). the boost creep that everyone talks about with the 3sgte is very true. i have a full 3" exhaust DP back, and ist gear is hit .9 bar and 1.1 bar in all others. i have yet to hit the fuel cut, it holds right at 1.1 but the waste gate is doing all it can to hold it there. i also run 100 octane in my car, lagged intercooler, aluminum radiator. everything else that 3waystunna said i completely agree with. do things the right way and you will be much happier and it will last longer. to run higher then the fuel cut you would have to use a FCD and the rev3 doesnt like them because of the map sensor. it keeps the map sensor thinking it is at 17 psi but its not so it doesnt add any more fuel. even with the factory tune that dumps fuel at the top end it will still lean it out, and then boom. the emanage is garbage as he said. so all in all once again just save the money go standalone and do it the right way. good luck with what you decide keep us updated.

[Island_Racer]

I figured it was garbage since recent, but i was like 18 when i bought it and i hadnt been home since (college abroad), thats why i was asking if i cud just do a temporary thing with it so i cud enjoy ma car a lil bit....Im still not even home yet, got like 2 weeks more.

at the moment i have:

255 lph Walbro
Electronic Boost Controller
AFR gauge
Silly Emanage Blue
and other stuff,

i only intended to go to about ~1.1 bar for now anyway (hence the initial question i asked about the limit before the ecu dumps gas in for safety and not performance), just to feel something since i been driving a damn protege on like ~0.5 bar for 4 years...lol....the blue as crappy as it is can manage to clamp the voltage of the fuel cut for me and i can use its simple functioning to raise fueling accordingly as to ur concern ST205WRC (great heads up man)....and thats all im gonna use it for (thanks to u guys really good advice) unless u guys know a good way to RAISE (NOT CLAMP) the fuel cut voltage (cause why would they tune the ecu's up to 1.1 bar if we wud have to re-tune it anyway)........till i rally up the proper elements for some serious driving.

Thanks again,

wait, one last thing....any of you guys have like a good table for "target value for AFR" up to like 1.2 bar....or know where on this site i can go look at some...cause im gonna need it

This post has been edited by Island_Racer: Jun 17, 2011 - 3:40 PM

[Island_Racer]

I dont think u meant to say the ecu is thinking it is at 17 psi ST205WRC......the clamping would hold the voltage just below our fuel cut threshold and we wud forever be tricking the ecu once we pass that voltage that we are just below 11-13 psi(whatever our cut is) even though we, in reality, have passed it....hence ur statement about needing more fuel.....am i correct? cause that was confusing me all day....lol

This post has been edited by Island_Racer: Jun 17, 2011 - 3:01 PM

[ST205WRC]

if you boost to 17 psi which just above that is the the fuel cut then it will hold the voltage there at that point. to be able to boost over the fuel cut the map sensor will read up to 17 and then will think it is still there when you go over it. and that is only if you have the right kind of FCD. there is one that is kind of like a peak hold that once you get to its setting it stays there and there is one that will pretty much make the map sensor its under full boost all the time. the second will NOT work at all. the other you would need to compensate like i said before.

[Island_Racer]

if you boost to 17 psi which just above that is the the fuel cut then it will hold the voltage there at that point. to be able to boost over the fuel cut the map sensor will read up to 17 and then will think it is still there when you go over it. and that is only if you have the right kind of FCD. there is one that is kind of like a peak hold that once you get to its setting it stays there and there is one that will pretty much make the map sensor its under full boost all the time. the second will NOT work at all. the other you would need to compensate like i said before.

ye, i was agreeing with you...the only thing i said different was that the fuel cut is between 11-13psi not all the way up at 17psi....well mine is at like 12psi

[Island_Racer]

if you boost to 17 psi which just above that is the the fuel cut then it will hold the voltage there at that point. to be able to boost over the fuel cut the map sensor will read up to 17 and then will think it is still there when you go over it. and that is only if you have the right kind of FCD. there is one that is kind of like a peak hold that once you get to its setting it stays there and there is one that will pretty much make the map sensor its under full boost all the time. the second will NOT work at all. the other you would need to compensate like i said before.

ye, i was agreeing with you...the only thing i said different was that the fuel cut is between 11-13psi not all the way up at 17psi....well mine is at like 12psi

[Island_Racer]

if you boost to 17 psi which just above that is the the fuel cut then it will hold the voltage there at that point. to be able to boost over the fuel cut the map sensor will read up to 17 and then will think it is still there when you go over it. and that is only if you have the right kind of FCD. there is one that is kind of like a peak hold that once you get to its setting it stays there and there is one that will pretty much make the map sensor its under full boost all the time. the second will NOT work at all. the other you would need to compensate like i said before.

ye, i was agreeing with you...the only thing i said different was that the fuel cut is between 11-13psi not all the way up at 17psi....well mine is at like 12psi

[ST205WRC]

do you have a gen3 or a gen2?

[Island_Racer]

gen 3,
i tried using the boost controller one time before i left and hit fuel cut same time so i assumed the fuel cut was right above the 12....i cud be wrong and might of been boosting higher than i thought.....like i said, i havent been in that car for 4 years, this stuff just comin into ma head since im going back now.

This post has been edited by Island_Racer: Jun 17, 2011 - 8:10 PM

[Neon90424]

fuel cut is 17 psi on 3rd gen

[delusionz]

17psi yeah,

on my gauge i see 1.2 bar the moment it cuts

dunno how accurate my gauge is but 1.2 bar = 17.4045285 pounds per square inch

[Domspun]

Well, for me it's over 17 PSi, because I am set at 17Psi and don't have any fuel cut. Does a FMIC affect the fuel cut? When I check my boost gauge, it cuts at near 19PSi