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Thread: Turbo whine overboost fuelcut

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    Turbo whine overboost fuelcut

    The other night the car car wheel spinned in 1st drove up to redline then ever since then my car when comes on boost makes loud whinning noise like a supercharger and hits fuel cut. The thing thats baffling me is the car is actually faster now as if it is overboosting. possibly the actuator is seized closed allowing to build up loads of boost im not sure. just took heatshields off turbo today and found 2 bolts loose on turbo elbow. tightened them up still the same. has quick look at intercooler piping joins vacum hoses etc. Will give them a better check when its not raining outside any ideas ? ive tried searching already.

    car has FMIC Decat back exhaust. thats it the rest is standard. No manual boost controllers etc.

    Thanks

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    Need to get a boost gauge on there, will tell us a lot.

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    i dont have a boost guage

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    It's just that if it's over boosting on the gauge then it would be a boost control issue, if it's less than 1bar of boost and hitting fuel cut it will be a boost leak.

    The whining will most likely be a boost leak or turbo gaskets

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    Banned sideways14a's Avatar
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    Get a boost gauge, also if its hitting FC then dont go hashing it especially if your using 95 octane fuel as you will kill it.

    Its likely a boost leak.

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    Guest ANDY black s13's Avatar
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    You can if you have a bike track pump with a gauge (the vertical type) rig that up to the waste gate actuator
    with the valve from an inner tube or any old car wheel valve (loads in the road/kerb outside most kwik fit tyre places)
    Schrader (standard car type) preferably with a length of hose to join the pump direct to the Waste Gate actuator ,
    and just pump pressure into it till the waste gate arm moves this will tell its not seized if it opens
    and the psi pressure it needs to move the WG arm
    get a boost gauge asap imo,if it reads vacume as well you can use that function alone to diagnose air leaks etc
    the whistling noise and hitting fuel cut sounds like the waste gate is stuck open just slightly,causing the 'new' noise
    and if it can't open fully to vent the exhaust drive that's also why its hitting fuel cut at 17 psi on stock ecu
    and hitting fuel cut is not a great thing to do often (it goes mega lean), as well as cramming 17psi into it won't do it any good
    on stock injectors ecu etc, deting its tits off springs to mind

    took so long typing and correcting speeling mishtakes sideway's beat me to it,,,, almost
    Last edited by ANDY black s13; 07-06-2014 at 15:56.

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    Banned sideways14a's Avatar
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    My boost leak detector went off at precisely 15:02 and 46 seconds however i couldnt be arsed to post until and hour and half later.

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    Guest Gymbob's Avatar
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    it has boost creep most likely or needs setting up properly... I gather it does it more in 2-3rd gear+ if you put your foot right down. Normally though boost creep and fuel cut is from too much loss of back pressure so a full through system without upgrading the intake and fuelling. Upgrade the fuel pump, and get a stage 1 chip and boost controller. It will probably run right then as you've changed the air intake and backpressure.
    Last edited by Gymbob; 07-06-2014 at 17:13.

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    Thanks for replys guys. I can get a shot of a cheaply digital boost guage from a mate. I'll fit that. How do you guys check for boost leaks do you know anything that's the exact size on the intercooler piping to block off ? Ill search more on that later. I fitted the front mount intercooler myself as the old wing mount was cracked. It's been fine ever since then about 7 months ago. The reason I went to the turbo first was because when I first got the car I could heard a slight blow from exhaust found the same bolts loose on turbo elbow so that gasket is most likely gone. I have a gasket there ready to be fitted only thing stopping me is the egr pipe that goes round the back of the engine I can't see an easy way to get it off without breaking it.

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    Quote Originally Posted by Gymbob View Post
    it has boost creep most likely or needs setting up properly... I gather it does it more in 2-3rd gear+ if you put your foot right down. Normally though boost creep and fuel cut is from too much loss of back pressure so a full through system without upgrading the intake and fuelling. Upgrade the fuel pump, and get a stage 1 chip and boost controller. It will probably run right then as you've changed the air intake and backpressure.
    its been running spot on for about 7 months after i fitted FMIC exhaust and cone filter. Dont think its that. dont want to get a chip and be running more power if somethings not right :/

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    Guest ANDY black s13's Avatar
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    Search on here for EGR delete/remove, I had a converted auto>manual 14a and it just had metal plates blocking off the were the pipes connected
    so I can't really advise whats needed to remove the pipe work and all my others have been factory manuals
    you can get creative with the blocking off pipe work with jars, bottles, wd40 tins etc till you find a good sealing 'bung' of sorts
    block turbo exit elbow hose and Throttle body hose and use the cold start/air reg pipe to cobble a tire valve into it so you can pump the
    system up to a bar or more 2 bar wont hurt anything tbh, and squirt soapy water from a trigger bottle over the joints and couplings
    its worth doing to eliminate a boost leak from the problem and check your work from when you fitted the FMIC
    I know its only 7 months old but check the cooler itself as well at same time
    link to the type of pump I use http://www.ebay.co.uk/itm/Topeak-Joe...item233873d45c
    you could use a fag lighter powered lazy man pump as well I guess
    just thought post a good close up picture of the waste gate lever as that will tell us if the
    waste gate is shut fully and if the lever weld has cracked and the shaft is 'walking' out of the ex housing
    causing it to stick/jam open possibly, I had it happen on one t28
    Last edited by ANDY black s13; 07-06-2014 at 21:21. Reason: more stuff added, I am a typing machine

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    He says the car feels powerful and is hitting fuel cut, so I doubt the wastgate would be stuck open.

    Are you using a boost controller?

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    Quote Originally Posted by redsx94! View Post
    He says the car feels powerful and is hitting fuel cut, so I doubt the wastgate would be stuck open.

    Are you using a boost controller?
    The car is faster than normal as if i am running a boost controller but I'm not. SO maybe thought the wastegate was closed allowing to build up higher boost therefor hitting fuel cut. Going on holiday on Tuesday so I'm just going to forget about it till I'm back. Pissing me off lol. At least I have a few things to try now thanks guys

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    Guest ANDY black s13's Avatar
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    Quote Originally Posted by redsx94! View Post
    He says the car feels powerful and is hitting fuel cut, so I doubt the wastgate would be stuck open.

    Are you using a boost controller?
    I mean't it's only open a tiny bit, like the penny valve is just off its seat, I had similar issue when messing about with a screamer elbow
    and the divider sort of melted and the 'gate was open a tiny bit
    it was laggy as fcuk boost @ 4k then 6k ish hit fuel cut
    reads as similar thing going on

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    Almost definitely a boost leak. Must fit a boost gauge in my opinion. The second you change anything about a turbo car you should fit one to be safe. Once you have done that remove the wastegate actuator pipework (including the solenoid) and plug a piece of pipe straight from your boost source onto the turbo and then see what boost you are getting.


    Sent from my iPhone using Tapatalk

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    Got back yesterday. Fitted boost guage. Boosting to 15psi then hits fuel cut. It's over boosting. Just need to find out why now. Made up a boost leak tester today but didn't have compressed hand pump etc so couldn't check that. Will check that next. I'm taking turbo off anyway to replace gaskets so will check wastegate and actuator then.

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    Is that on actuator pressure?

    If it's just at 15psi it shouldn't hit fuel cut unless there is a boost leak

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    Quote Originally Posted by redsx94! View Post
    Is that on actuator pressure?

    If it's just at 15psi it shouldn't hit fuel cut unless there is a boost leak
    What do your mean on actuator pressure ? Can you explain a little thanks
    Last edited by maaaaarrrrrk; 19-06-2014 at 21:22.

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    What do you mean by boost source ?

    Why would it make more than 10 psi if it's standard and if there's a boost leak then why is it building up that much pressure. Surely would be "leaking out" therefor less pressure not more ? Or am I being silly lol
    Last edited by maaaaarrrrrk; 19-06-2014 at 21:25.

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    Banned sideways14a's Avatar
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    Doesnt quite work like that.

    There is no pressure sensor in the s14 to determin what boost you are running, its all read from the air flow meter. If your afm reads 15psi of air passing it then the ecu thinks "15 psi, heck gota fuel that".
    However if you have a boost leak, like somewhere at the IC then a couple of ps might leak out, but the ecu still fuels for 15... cos thats what it saw. Hence why we see overfueling with boost leaks.

    Similar story with a possible fuel cut issue on yours.
    AFM could be reading 17psi or more, there is a leak and you read circa 15... but the ecu sees 17 and goes "ohh shit loads of boost quick hit the fuel cut or i will explode"...

    Why could you be hitting that amount??? well if everything is 100% stock then it could be that the FBU has been done to it, this is the free boost upgrade which is a naff way to pump up about 5 psi, its removal of a few restrictors in the vac pipes making the stock setup overboost. Its not very cleaver.

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