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Fuel cut - did it just happen to me ?


DArby
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Got the NurSpec R drilled baffle exhaust fitted yesterday. And ran it in anger for the first time today (thats what happens when your brothers in the car !!)

 

I was really give it a go down one of those lovely MK dual carriage ways when all power ceased and the warning triangle came on. What seemed like an age, but probably only 2 or 3 secs, eased off and everything came back on again.

 

I've never seen that before !! - No cats either so i guess that all helps.

 

So if it sounds like fuel cut i guess i need a Pete Betts FCD.

 

Also noted that even with new exhaust no cats etc. still only get 1.0bar boost...

 

Oh yes, UK spec by the way

 

 

Dean.

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I guess it could have been fuel cut - if you hit 1 bar then that is about 14.5psi, and fuel cut occurs at 14psi, so makes sense. From what I've heard, fuel cut is pretty violent and would not be a pleasant experience.

 

You definitely need to get hold of Pete Betts FCD.

 

Only getting 1 bar from a UK car without cats / free flow exhaust is normal.

 

Eric

 

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Yep agree with Eric - you definitely need a Fuel Cut Defencer from Mr Betts.    mailto:[email protected]

or his site : www.trlperformance.com

 

I've got one on my car like many others and it's never hit fuelcut or done anything weird.   About £60.

 

Also your 1.0bar boost reading ties in well with both my own experience at that level of tune (no cats, aftermarket exhaust) as well as Eric's.     Eric had about 15psi by memory (just over 1 bar) and I only got 0.9bar !!    

 

By the way, obvious i know, but the big performance increase comes in from 1.0bar to 1.25 bar.  

you're going to need either an electronic boost controller (like Blitz DSBC) or the cheap solution that i currently use is a bleed valve.    i'm quite happy with the bleed valve really.   does the job, and is 100% reversible if the person who i sell my car to eventually doesn't want it.

 

I'd heard that fuel-cut is fairly dramatic and a bit violent but it sounds like your fuel-cut (if it was that!) was a little more genteel ?   maybe this is another UK vs J-spec difference ??   UK-cars have a "softer" fuel-cut ??just guessing here.

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  • 1 month later...

hi people

 

great board

 

 

i just had my de cat pipe fitted to my jap supra twin turbo auto

 

i was going to cleethorpes a few days ago and decided to put my foot down

was doing about 80mph then floored it got to 120mph

and the same thing happend to me

 

the power cut out and the warning light came on on rev counter just below the 4000rpm it was the triangle warning light

 

i have BLITZ nurspec r cat back exhaust and cat replacement pipe and dump valve and induction kit all BLITZ products

 

 

i s**t myself wonderd what it was

then it did it to me on way home when i floored it at different speeds under hard flooring

 

if i slowly build the speed up it pulls to 140mph + with no problems

 

is there a good make of FUEL CUT DEFENCER

 

and are they easy to fit

 

i am looking into buying a BLITZ

latest boost controller and power meter

 

am i hitting boost levels on the system i have now?

also if i get the new boost controller will that cure creeping boost

 

i am new to tuning and having fun trying to learn

 

any help would be gratefull for

 

thanks a lot

 

ps i got no boost gauge to check what boost it is rising to

 

is standard boost 10psi

and what boost could i expect on the mods done so far

 

it seems loads faster with the de cat pipe fitted WOW :)

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MonkeyMARK

 

You do need an FCD.    See the posts above in this thread referring to where to get one.   Pete Betts @TRLPerformance.    you can fit them yourself - depends how happy you are with a soldering iron and cutting wires to your ECU.

 

You must also get a boost guage to see what you're boosting to.

With a Jap spec and no cats and a Blitz exhaust you will be getting MAJOR boost.   BUT the car is restricting it as when you hit approx. 14-15psi boost, that is the level at which the car cuts fuel to "save" the engine and turbos.     When you get a FCD installed, it *raises* the fuel-cut to approx. 18psi therefore allowing the car to boost to this level.     MAximum boost it is advisable to run is approx. 17-18psi.    Opinion varies on this one......

 

So to summarise :

Stock boost is approx. 11psi

Fuel cut happens at about 14-15psi

Get an FCD to raise the fuel-cut

Get a boost guage to see what boost you're running

Not advisable to boost over 17-18psi

You may need a method of controilling the boost such as a bleed-valve or electronic boost controller.    Jap-specs tend to get much more boost than UK-specs with the mods you have and can have overboost problems.

 

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They are adjustable.   (as long as you get one with an adjustable screw !).

 

You do *need* a boost guage for this.   Simply start off the bleed-valve closed and then open it up, say, 1 turn.    Then drive off somewhere and give it full throttle in 4th or 5th and see the max.boost you get on the boost guage.    

If it's not enough boost, then stop, flip the bonnet, and open up the bleed-valve screw a bit more etc.etc.      Repeat until boost is as you want it (mine is about 1.2bar).

 

Only downside is that the boost varies a bit with the air temperature.   i.e. cold air you get more boost.     not really a problem as you can adjust the valve as the season's change.        

I think CW sells brass bleed-valve's for about £10 or so !   hell of a lot cheaper than £350 for a DSBC + £2-300 fitting.  (=£600-700 !!)

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They can be found at most accessory shops I believe (not Halfords)

I got mine from Interpart in Wycombe (see MP3 thread for no)

AFAIK the manufacturer/distributor is Le Mans Motorsport?? they supply dump valves, bleed valves to the trade

 

Demon Tweeks sell the same thing , but its inexplicably more expensive from them than everywhere else

 

The valve comes in three colours; anodised red or blue , and aluminium...... all with a muppet "Turbo" logo on the knurled knob :biggrin:

 

Seriously it doesn't look that bad......

I have mine where the active spoiler switch used to be, which is pretty convenient

 

Beats the hell outa stoppin the car and tinkerin under the bonnet to change the boost...... :wink:

 

 

 

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Doughie

 

thanks for info

 

i have still got my front pipe that comes off the turbo elbow

 

i have the full cat back exhaust and the middle cat replacement pipe

 

i know it is getting more serious on the tuning side

 

will have to get a boost gauge (blitz)

 

i will have to move away from blitz and get some other makes like hks or other makes

 

can anyone reccomend a boost gauge with warning limits or audio warnings

 

i would like to get a electronic boost controller

i would feel more safer with them

 

i know a few non supra owners who have manual boost controllers and are happy with them

 

any other good products would be great

 

thanks again group

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I still have my first cat in place as it is the last bit of restriction in the system. I  was hitting fuel cut too often before fitting  PB's FCD.

Jap specs suffer from boost creep with the cats out whereas UK car have some other pipework??? that seems to stop this.

 

The front cat stays in until I get some form of boost control.

 

(Edited by Phil Wall at 5:04 pm on Sep. 24, 2001)

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You do need to be aware with a manual boost controller that you have to keep the boost below the level that an electronic one can maintain. The available boost with the manual controller can vary by 3psi or more and if you are running on the limit of your fuelling and turbos the extra 3psi might be enough to cause some damage.

 

The electronic units measure boost and hold it at the required level no matter what the weather conditions. The only exception to this is when you have removed your cats and the boost is uncontrollable. Careful use of an electronic boost controller can manage the overboost though, but make sure you get somebody like Leon to set it up for you.

 

I took the easy option of using neither and just letting the boost go uncontrolled...means I have to watch the boost gauge like a hawk though.

 

JB

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yeah that's a good point from Paul.

 

Pete's device raises the fuel-cut but doesn't eliminate it.  (which is a good thing!).

I talked to Pete about this at the time and it's hard to tell at *exactly* what level of boost his device will allow.   it's approx. 18psi but it's set by a tiny screw adjuster on the FCD box which is a variable capacitor i think.

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Good point from JB about EBC's. ......

I should've mentioned that I first fitted a cat replacement pipe (2ndcat) . This had little or no effect on boost levels

 

I then fitted a Dual Dragger and this again had very little on boost levels (ie no creepin)........ so I decided to fit a MBC as I didn't have runaway boost to control

 

I'll probably have to have a rethink when I remove the 1st cat..........

 

Re FCD's , I have fitted the HKS version, but  this is not the best unit to go for , by all accounts....(search for FCD threads)

 

One more point ...... I believe the EBC 's (most if not all) display the boost levels accurately, so negating the need for a seperate gauge.

Although they do *look* good, Paul :biggrin:

 

 

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Quote: from Doughie on 6:20 pm on Sep. 24, 2001[br]

 

I talked to Pete about this at the time and it's hard to tell at *exactly* what level of boost his device will allow.   it's approx. 18psi but it's set by a tiny screw adjuster on the FCD box which is a variable capacitor i think.

 

Paul if you talk to Pete he will talk you through adjustment of the two adjusters on his unit.

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The problem with the EBC's displaying boost, try taking your eyes off the road then down to a boost controller. If you are hitting 1.2bar, you're travelling pretty damn rapidly, and if you're eyes aren't on the road, you're probably heading for a brick wall :)

 

That's why I liked my boost gauge housed on top of the instrument binnacle (see Stu Hollows pictures, member number 16 - we both had the same gauge in the same place), it's more or less 'line of sight' when you are looking out of the windscreen, you don't have to divert your eyes too much.

 

Eric

 

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Yep, that's why Paul mentioned about the fact that I hadn't reco'd an HKS boost gauge as one of my choices... you need an 80mm boost gauge right in front of your face on the dash.

 

Yours,

J

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I have Petes unit with the fuel cut totally removed as I found I was hitting it at Pod on full throttle runs. His unit will stop the boost at 18psi, but then it just fuel cuts which you shouldnt really keep doing to a mkiv.

 

The ideal solution, assuming your insurance company really like you, is to fit a PeteB FCD or HKS FCD, full decat, Nur Spec or SuperD exhaust and a Blitz DSBC to control the boost DOWN to a reasonable level. If you have a UK spec you wont have overboost problems unless something else is wrong with your car. It might be possible to control the boost down with the Apexi and HKS gear, but I have only seen it done with the Blitz.

 

Im now in the situation where Im running as much boost as I can, but if I fit a boost controller to keep the boost down my insurance company will jump me for having another mod.

 

JB

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Quote: from Phil Wall on 7:01 pm on Sep. 24, 2001[br]
Quote: from Doughie on 6:20 pm on Sep. 24, 2001[br]

 

I talked to Pete about this at the time and it's hard to tell at *exactly* what level of boost his device will allow.   it's approx. 18psi but it's set by a tiny screw adjuster on the FCD box which is a variable capacitor i think.

 

Paul if you talk to Pete he will talk you through adjustment of the two adjusters on his unit.

 

No s**t Sherlock! You should see my inbox/sent folders for today alone.

He's offered to fit it while he's under my dashboard with his scope - well, he's under there anyway, might as well make himself useful).

I've said I want my safety limit set to 17 psi (ok, call me over-protective    http://www.stopstart.fsnet.co.uk/smilie/naughty.gif).

 

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Guest Martin F
Quote: from Eric Kasir on 7:11 pm on Sep. 24, 2001[br]The problem with the EBC's displaying boost, try taking your eyes off the road then down to a boost controller. If you are hitting 1.2bar, you're travelling pretty damn rapidly, and if you're eyes aren't on the road, you're probably heading for a brick wall :)

 

That's why I liked my boost gauge housed on top of the instrument binnacle (see Stu Hollows pictures, member number 16 - we both had the same gauge in the same place), it's more or less 'line of sight' when you are looking out of the windscreen, you don't have to divert your eyes too much.

 

Eric

 

 

I concur with this 100%.

 

I have the DSBC on top of my steering column and it is next to impossible to read the display when you are WOT. I tend to end up using the peak hold function and scaring myself silly when i review it!!!!!!

 

Hence my purchase of a seperate boost gauge and A pillar pod. (plus an EGT gauge)

 

 

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Whoever posted earlier today about the human brain needing to convert changing figures to a visual respresentation was spot on (Paul ??!).

 

that's why an analogue display boost change is necessary.

also why, for example, TVR Tuscan's recv-counter in digital LCD, has been almost universally acclaimed as being next to useless as the brain just can't assimilate rapidly changing numbers easily enough.

good ol' fashioned needle on a dial is what you need...

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