Fuel Cut Defender For 7mgte ????
 

hEY GANG

Ive just bought a new FCD for the 7mgte, does anyone have any idea on how,what and where to wire this thing up. Everytime I try and boost her up a little, the Fuel Cut Off kicks in - Ive just gotta get this FCD to work !! Any tips would be much appreciated !!!! Thanks

what sort of fcd did you get? hks, greddy etc?

http://supra.co.nz/fcd.htm

sorry, noobish question to follow
 

does a fcd remove the top speed fuel cut thing or does it just let you run more boost out of your turbo ?

fuel cut is initiated by the computer when too much airflow is introduced to the engine (cuts fuel)

when going really fast... that's called speed

and when you hit a cut at speed it's called speed cut in which case you need a speed limit defencer :)

If I am going to increase the boost and I will eventually, how do I defeat that sensor?


Russ

well that depends

some ppl like to just get a boost controller on there and turn it up silly and have no fuel upgrades to support it therefore when they stick on the fcd they end up running a bit lean and then boom! funs over

other ppl are prepared for a fcd and buy a walbro pump and raise the boost max to 12psi (depending on what mods) and install a fcd and never alter their boost controller

basically you need to tell us what mods you have in order to suggest when you need the fcd and what boost you can run as it varies alot
if you have a dyno nearby that would be even better but not everyone has those
or if you have spare money to burn buy a wideband so you can keep an eye on it :)

Well no mods to speak of yet, but I will in the near future. That is why I was asking about the pressure sensor. I notice there is on on the driver side engine compartment between the fender and the top of the shock tower. Does this sensor just measure fuel pressure and if it drops too much then it shute the engine down to protect it? And if so is that how you can make it stop cutting the engine just by adding a walbro or other high volume pump?

According to my aftermarket boost guage I am right at 10 psi. I played with the adjuster and got more boost but it didn't take long for it to shut the engine down for a few seconds. I know the stock turbo and wastegate won't go much past what I am putting it at and I know I need a better head gasket, etc..... but I am very curious about why and how the sensor shuts down or limits the engine if you over boost.

I thought it might be sensing the boost level, but now I wonder if it is a fuel pressure sensor or does it measure the boost and the need for fuel. If it doesn't sense enough fuel for the boost given it, is that why it shuts down or acts like a rev limiter.

I guess I am asking then, if I put a walbro fuel pump in it and then turned the boost up, would it continue to shut down or does that fix that problem. Blowing the engine up not withstanding I mean.....lol

Thanks

Russ

fuel cut all happens in the air flow meter

the airflow is changed to a frequency of hz
when the frequency hits about 1500hz fuel cut is introduced
so basically when a certain amount of airflow comes thru the afm tells the ecu and the ecu spits the dummy and throws on fuel cut

the only way to stop the ecu from laying on fuel cut is to trick it by telling the ecu there is less air getting in (i.e fuel cut defencer)

fcd's clamp the signal at about 13-1400hz and the ecu never knows how much air is really in there
which is why you have to be really really sure you have the fuel available to compensate what the ecu doesn't see

example
lexus and 550cc injectors

you put on a lexus afm and now your car is getting 25% more air but the ecu doesn't know it is... it sneaks in thru the side chamber
the stock ecu is still delivering fuel for the air it can only see thru the main chamber.... suddenly you are 25% short on fuel.... if you go wot on this you may very well damage your engine
so to fix this fueling problem you add 550cc injectors and it's all evened out again

also there is no fuel cut as the ecu doesn't see the 1400 or 1500hz ever again (till 25psi or so) as the extra air is sneaking thru the side (so it's another fcd of sorts)

lemme know if this needs further explaining :)

No, you covered it just right. What you said makes sense and now I know the directions to go with this car. I knew about having to get bigger everything, don't say anything....lol, but the fuel cut was bothering me as to where and why it was happening.

So as a start I will look for the Lexus afm. It would have been so much better if Toyota would have done that first. Should the Lexus afm just plug right in, except for needing the bigger connecting hose?

Thanks

Russ

yep the lexus is a bolt on

if your accordian hose is old and plasticy it will more than likely break when you try to put it on
so find a really really good condition one that is still actually rubber or buy a new one, least you know you won't break the hose and then break ur turbo coz the hose broke :)

related side-note ;
 

suprra_girl you're a kiwi right ? where can i get an accordian hose from ? toyota told me a couple hundred dollars and three weeks from japan.

i'm on my second one right now. its from a wrecked car and way better than the origonal one ... it's just cracked, not broken off in chunks and glued back up

dont get that ugly acordian hose! lol....i just went to a local import shop and got a 96-00 civic intake pipe and cut it. and the old ugly acordian hose is no longer there. it is now a nice shiney intake pipe! it cost me 60 bucks for the pipe and like 3 bucks for the 3inch coupler

cool. was thinking of mothering something after-market in there for an intake and pod filter

picture me muttering " need ... 3" ... exhaust " all my waking hours and " need ... pod ... filter ... " when i sleep

what year lexus's do i get teh AFM from??????

don't forget that the accordian hose has the 3 plumbback holes in it for various breathers

i think i could get a new accordian for about $100 from toyota

if you like you can pm me if you are serious and i'll get a firm price for you tomorrow

i believe the afm from any 1uzfe lexus v8 is the one you are after

I have a 87 turbo supra with full 3 inch exhaust 12 psi of boost, adjustable fuel regulator. Every time I run my engine up to 5,000 rpm, it starts acting like a rev limiter but no check engine light is on, is that my fuel cut. The only sensor I don't have on my car is a turbo boost sensor, I thought it was only used for the cluster boost gauge. It also did it at 9 psi so I have no clue what it is. The only code I got is a boost pressure signal, it don't sound like I have boost leak.

sorry to disturb this flow,
but i askd this question and never had a response b4

but what actually happens if you hit fuel cut?
and whats the worst that can happen when you hit fuel cut?

and does mk3's come with speed limiters?

the worst that could happen is you would shit your pants when you hit FCO for the 1st time


the engine cuts out for about 1/2 a second then resumes

why does this scare me more than the thought of my engine exploding?

gomez, no you aren't hitting fuel cut, do a diagnostic and make sure you don't have any other problems

fuel cut has been described as hitting a brick wall
it is extremely violent lol

supra2nr: LOL i know what you mean, it's not the best feeling, ya just gotta think... is this actually ok for the engine to cut this violently... i think it best to turn boost down a bit to avoid it because constant triggering of fuel cut can't be good lol

i kno engine problems are scary, i was 20 miles away from my house when my threw my rods in my n/a
and i was in a baaaaad neighborhood
so it was either i limp it home
or im gonna go home limping

but the crapping your pants??
can you imagine going back to the crowd back on the line after you won a race
then pple will see that you jus laid fudgy in your wedgie
there's at least a hundred pple in here every weekend

so it gets you to think which one is worst
youre engine hitting a brick wall
or
crapping yourself in front of a hundred pple?

supra girl, I viewed your pinout diagram for installing a fuel cut defencer, I don't understand the harness side and ecu side. also does the defencer have to for specific for my car or will a universal work?

gomez: don't you have misfiring and/or PROBLEMS with your mk3?

why on earth are you installing a fcd?
do you fully understand what a fcd does?

Yes my car sounds like its has a rev limiter cut out and I get less of a rev limit problem with less boost so and I do have a high volume intake system which is giving me a fuel cut out earlier than normal. It's the only thing I can think of right now. I know fcd changes when the fuel cut comes in so that why I think its the fcd giving me these sounds like a rev limiter is kicking in. Just to make it clear, I know what a rev limiter sounds like and it sounds like a somewhat misfire/backfire.

^ and exactly

for this problem you don't buy a fcd
it will not solve your problems

it will move clamp fuel cut, you'll up the boost, the ecu can't supply enough fuel for the boost you will then run then you'll blow it up

not something you want to do i imagine

the only thing that i can suggest really is new plug leads and make sure your clutch isn't slipping which is causing you to hit rev cut quickly

the day you hit fuel cut, you will know it and you have not hit it ;)

edit: so what does it feel like? fast bap bap bap bap bap
or does the car shut down for a second?

just an intake will not cause you to hit fuel cut
you need alot more mods to cause the problem at low boost

what is your stock boost level and what are you trying to run?

Then how come other people say they hit fuel cut at 8psi.

that other ppl is me

and you still need more than an intake for it to hit low ;)

k lets get this straight lol

what does it feel like, shut down or bap bap bap

what mods have you done
and i want all the mods exactly what you have done

like what?

what do you mean

like what?

what modifications have you done - engine wise

I have full 2.5 intercooler piping, aftermarket intercooler, stock boost is 6 psi and it didn't cut then but when I raise the boost, it cut outs. the car does a bap bap bap noise.for sure the clutch is not slipping.

if it does a bap bap bap noise it is NOT fuel cut so don't waste your money buying one

so you're saying that when you run 6 psi it doesn't cut at all

but when you run (what psi???) it does cut

what psi are you trying to run?

I normally run 10-12 psi

10-12 is to high for stock running. try running around 7-9 you should get ver minimal fuel cut.

BapBapBap Fuel Cut?
 

Hey Girrrrllll. First off, I LOVE YOUR CAR, secondly,

I am hitting the bap bap bap kind of fuel cut like you explained! PLEASE HELP!
I am at 9psi, Gt35 turbonetics turbo, lexus AFM and 550cc RC engineering injectors, Walbro fuel pump, and Adjustable Fuel Pressure Regulator...
Stock ECU, and I only want 350 Hp. My wastegate wont allow lower boost than 9 psi and I am hitting the bap bap bap fuel cut. I have a EUGO guage to moniter my air flow fuel flow ratios, and it is rich all the time even when hitting fuel cut "bap bap bap" and it bucks the car when this happens, is a HKS Fuel cut defencer safe if i carefully watch the air flow ratios?

If you have all the equipment to monitor your afr, I don't see any reason why you can't use a fcd.

I use one in my vehicle due to my upgrades flowing that much more air that before fcon with my ecu it managed to throw cut in heh.

Just bear in mind that by using the fcd, it won't remove it, it just scales it up further, you can use a fcd and pray that your mods don't go as flowy as mine. Ideally you will need to obtain an aftermarket ecu for the end game.

Atm, with hks fcon, rx7 550 inj, custom intercooler/piping, to4b h trim garrett, 3" exhaust I was pushing 340hp at the wheels on 14.7psi with really really really bad fuel tuning (no fuel cut either), it was tanking in the 9's for afr wot so I now just patter it around town daily driving it till I can give it the ecu it deserves ;)

TBH if you're hitting cut at 9psi, you more than likely have a leak somewhere, double check the basics first as you don't wanna miss something little and have it damage your car. On the other hand, before the fcon I was also hitting cut, but yeah just make sure you've covered the basics.

What is your afr at idle?

The other thing to remember folks that may read this in future, 7mgte fuel cut is very abrupt/violent, it will rev out and then it will be like someone just killed your ignition, it will take a few secs to come off fuel cut, then when boost gets back up to max it will do it again, it's like hitting a brick wall. Make sure you are indeed hitting fuel cut and not experiencing another ignition problem, also the check engine light should illuminate when hitting cut but it can also illuminate when having other problems :p

Do yourselves a favour and check your codes, fuel cut should throw a 34 iirc, abnormal turbocharger pressure.... amusingly enough ;)

Other regulars feel free to correct or add information, it's been a while since I had a stockish car with stockish problems :p

GL

Yep, if you didn't feel sick for a second, thinking you'd thrown a cambelt the first time it happened then it probably ain't fuel cut!

Just to avoid confusion for the future benefit of spainobain, the post you originally quoted said "bap bap bap noise it is NOT fuel cut ". If you refer to it as fuel cut then you'll likely get people muddled up & receive wrong advice... Not saying this to jump on anyones back or anything so don't bite my head off, just don't want you to hurt your engine at all :)

What rpm is your rev counter showing at the time of the problem? IIRC it'll start "bouncing" off the rev limiter actually just before the redline (at least on my JDM dash, not sure on the analogue ones though)...

Rpm Rev When Happens
 

At 4,000 rpm on the rev counter, the problem hits, CEL flashes, and the car bucks (hesitating and hitting a brick wall, then boosting, hitting a brick wall, then boosting again...)
Sidenote: Also the car wants to die if I tap the gas pedal in gear and let off, the rpms drop and the car dies.

My Afr at idle is at 10, pretty rich, I know. The car sputters during acceleration, but idles smooth at this rich ratio. When I tweak the ratios using the SAFC, bringing the afr's to the 12-13's range of the ratio, the car seems to accelerate smoother.
Maybe I need a different piggy back. Which would you recommend being the cheapest way to eliminate the stupid Lexus AFM. Its ugly anyway! Lol

How to tune SAFC with Wideband o2 Gauge?
 

Please answer this,

"How do you tune an SAFC with 550cc injectors and the MAF?"
or
What are the steps 1-10 on how to tune with an SAFC and Wideband?

My car drives like crap hitting fuel cut because I cant get the tune right at higher rpms because I am not going to HOLD my throttle at 5,000 rpms for 20 seconds to get the Wideband o2 gauge to tell me its running a 12 A/f ratio at each RPM.

Problem... When I set my a/f % at a certain rpm on the controller, a minute later, the car evens out and changes the a/f ratio.

example, I set the a/f ratio % on the SAFC to +22%, and the A/f ratio is at 12... a minute later, after reving the engine, the car will be at a/f ratio 10 and extremely rich!

OMG thank you SupraGirl!!! I Love you.
Finally all my final codes are code "34"
FUEL CUT!
YEAH! I have completed the Supra!
HKS FCD, here I come!

http://www.youtube.com/watch?v=RFW3-wl939A