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The mkiv Supra Owners Club

fuel cut-out?


Irvy

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hi folks

am hoping to get some help on yhis issue(s)

bought my car stock and have recently put a Nur spec exhaust on, blitz induction, had a single cat removed and a TRL FCD put in.

When accelarating hard at around 60 or 70 and heading past 100 the ride aint smooth as the car seems to - how can i describe this?-pop along!!!

Along with this i have experienced on the 100 mark or just beyond had the car stall like the brakes had been applied hard (just for a second or so)

I have found that placing the baffle in the exhaust helps a little and I rejigged the FCD from setting 8 to 7...this appears to have assisted slightly.

am i doing the right thing by purchasing a walbro as I am assuming my fuel may be the problem

any help/assistance greatly received

irvine

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It does sound like it might be fuel cut. Do you have a boost gauge? At what boost level does this problem occur?

 

Fitting an uprated fuel pump will not stop fuel cut if the ECU is cutting the fuel supply because of the increased boost.

 

 

There are good reasons for fitting an uprated fuel pump but stopping fuel cut isn't one of them.

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The non smooth bit will probably be your spark plugs breaking down and being unable to cope with the higher boost. When I came across it I described it as a soft cut as I thought it was the FCD, but I was wrong!

 

Proper fuel cut is a big brown trouser moment the first time you hit it. the red triangle comes on and you think it's badly broken.

 

The FCD just raises the stock fuel cut.

 

Have you got a boost gauge - if not GET ONE NOW before driving hard again. Stock plugs give up about 15-16psi normally. Going above 18 with stock fuelling and turbos is unwise....

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Sounds likegood advice...had a feeling i was on the right tracks

I do have a boost gauge - just not fitted yet.

Also will have the plugs changed to make sure.

will drive likes its sunday all week!!:innocent:

thanx guys...will let you know how i get on once the pump is in and the plugs changed.

Irvine

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Exactly...

 

 

So it's likely the VFCC is actually reintroducing the fuel cut at a higher boost meaning your car is boosting beyond 18.5->19psi.

 

This is the O'boost setting of B (4.95V)

 

 

HOWEVER!!!!

 

I will stress that this MUST be associated with the same RED TRAINGLE warning light on the dash or it's NOT fuel cut.

 

I've had many people say that the VFCC didn't work only to discover that in fact it's either plug mis-fire (like a RPM limiter) or Top Speed limiter related.

 

Pete

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Originally posted by Chase

When I hit fuel cut I don't get the red triangle lit up on the dash...

 

Then either it's not fuel cut, you've got a broken red light or it is cutting the fuel in another way.

 

What does it feel like when you get your fuel cut?

 

a) soft rev limiter

 

b) big wallop, total loss of power for a couple of seconds then back to normal

 

c) something else?

 

Supratoy, a boost controller allows you to control the boost. Fuel cut is a safety device to help prevent the engine melting.

 

 

 

BTW, hi Pete, not heard you for a while.

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It's defo b Steve. I can do it predictably as well...Feels like hitting a brick wall, then back to normal after a second or so. I've got a TRL FCD here waiting to go in, so if it stops after fitting that, then it must be fuel cut.

 

No blown bulbs btw...well not behind the triangle :D

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Originally posted by Chase

No blown bulbs btw...well not behind the triangle :D

 

If it's stock (or raised) fuel cut you will get the red triangle. Does this bulb come on, I think the handbrake lights it.

 

Is it possible you already have some other electronics in there?

 

Or...... you are too busy watching the road as you are at WOT to see the light come on?

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Steve,

 

Trangle bulb deffo OK - Lights up with handbrake/door open etc.

 

Not seen any extra electronics when I've been in the footwell fitting RLTC & ETTC.

 

I've fitted a Walbro and BKR7E's after it was missing at high revs/boost after fitting RSR.

 

I suppose I have been staring at the road at WOT :D, but I'll check again tomorrow that the warning light doesn't come on.

 

You got me wondering now...I was pretty sure it was fuel cut - hitting 1+ bar for about 3-4 seconds then it would cut. (maxing at 1.2 bar)

 

If it's not fuel cut, whjat else could it be?:blink:

 

Cheers

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Chase, stock fuel cut is under 1 bar, it's about 14PSI. Stock plugs give up at 15-16 PSI, so you'll hit stock fuel cut before stock plugs start to give up.

 

Sounds very much like you already have something playing with the electronics. As you had to change plugs already.

 

Removing cat 2 you will be able to hit fuel cut on cold days. With a full decat and big exhaust you'll be there all the time!!

 

Pete's one allows you to raise the fuel cut (within sensor limits) to what you have determined is the safe maximum of your engine build, it's part of the tuning process.

 

I'd get it looked at properly.

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Originally posted by Steve Cargill

Then either it's not fuel cut, you've got a broken red light or it is cutting the fuel in another way.

 

What does it feel like when you get your fuel cut?

 

b) big wallop, total loss of power for a couple of seconds then back to normal

 

 

This is what i experienced...wish i knew my boost level.

tomorrow i am having NGK platinum plugs fitted (and just found a web site saying poor choice!!! oops!!).

guess i gotta try something tho... I just wont go fast till my pillar arrives for my boost gauge. Have a better understanding then:confused:

ps...never seen my triangle light up either

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hu guys

I got my new plugs this afternoon...and would you believe it...60 - 120 was shoooo shhhmooth!!!! (Mish Moneypenny!!:thumbs:

I am still having the pump fitted when it arrives andmy boost gauge also just to make sure all is well.:lalala:

Had a thought tho...i went for these BPU's without much thought and didnt find a thread explaining how to go about it - IMO it should be sorta - spark plugs, pump (if required) then induction followed by decat and exhaust...this may negate the problems i was wxperiencing.

i now gotta re set my FCD:devil:

Irvine

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Originally posted by tbourner

Bloody hell why are the simple things so damn hard!!!!

 

If you've never done it before be super careful with the coil pack connectors. They will be brittle and break easily.

 

Before you ask they are part of the main wiring harness. I think somone has manage to get replacments though, but best not to break them.

 

If they do get broken then make sure you put them back on the roght way around.

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Originally posted by Steve Cargill

If you've never done it before be super careful with the coil pack connectors. They will be brittle and break easily.

 

Before you ask they are part of the main wiring harness. I think somone has manage to get replacments though, but best not to break them.

 

If they do get broken then make sure you put them back on the roght way around.

 

I allways keep a full set in stock steve , more and more are breaking .

 

Dude:flame Dev

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