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Discussion Starter #1
JUst drove home from work, car was fine all the way back (40min journey). Nearing the end of my journey, wen to set of at the lights (easily) and as soon as it hit 3k revs it back fired and boost cut off jolting me forward.

Then the same in second when came to the turbo's kicking in. But then i gave it some and was fine, but then again cutting boost off at 3k revs??

Anyone know of these symptoms?
 

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Sound kind of like what was happening to mine a while back Faz. Seems there was a boost hose that, whilst still connected, would unseat once the boost got to a certain level and dump all the pressurised air. I was puzzled as to why this would happen and only got to the bottom of it when the hose finally popped off properly. In my case it was the one fron the 'twin turbo' pipe to the inner wing pipe (32 GTR)
Best advice would be, when you've got a spare few hours, remove all the hoses and physically replace them on their reapective pipes. I would never have spotted my loose hose in a month of sundays had it not come off.

TT
 

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Faz,

Have you got a Power FC fitted? If not like TT says sounds like some problem with the boost pipes?

Dave.:confused:
 

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Hmmm well like Faz said, it only happened at low rpm, if was loose pipe, and when he gave it some all was fine, surely pipe would have blown off altogether?
 

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Hmmm well like Faz said, it only happened at low rpm, if was loose pipe, and when he gave it some all was fine, surely pipe would have blown off altogether?
thats the weird thing,on our GTR,it makes the car really funny at low rpm,but if you drop it down a gear or two,everything goes back to normal after you give it some of the right foot,as the truck found out on the way to JapFest II on sunday :flame:
 

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Discussion Starter #8
i'm a bit puzzled? Just went out into Central with it and drove for about an hour and a half altogether and car seems fine. I drained all the fuel out and refilled with proper stuff from my local. Only thing i could really point my finger at is maybe a dodgy batch of fuel??

Guess i'll find out in the next few days whether it was the fuel or not...
 

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Maybe its your MAF sensor on its way out.. thats what it sounds like to me..
 

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Had a similar experience in mine years ago when running on standard turbos.

Used to be fine and then not boost above 3k and then fine again, until eventually they gave up.

From memory, I think it was the wastegates seizing and then reseating etc.

Hope it's fixed now Faz.
 

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Do you have vents in your bonnet? I've heard that water dont do good and as matt j said can seize the wastgate. If you look at the design of the wastgate, you will see that its very easy to seize if not looked after

P.S mate I see your skyline on dirty sanchez
 

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Might be AFM as well. On my 34 I had a similar problem and it just got worse untill they gave up.

If you have anyone local with one try theirs and see how it goes.
 

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Might be AFM as well. On my 34 I had a similar problem and it just got worse untill they gave up.

If you have anyone local with one try theirs and see how it goes.
Alright mate, can you explain the AFM please, ive wanted to know for a while?:confused:
 

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what would you like explaining matey??

TT
 

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just the basics of AFM and what it is really?

I know only bits about an engine but im keen to learn.

Thanks TT
 

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Basically the AFM uses one of two methods, Flap type (e.g Bosch K Jetronic ala Pug 205 GTI) and Hot Wire type (errr...GTR) to measure the amount of incoming air into the engine and tell the ECU to dial in the appropriate fuel to maintain a preset mixture ratio. In basic terms the flap type AFM utilises a flap which displaces when the air rushes past it which in turn creates a voltage which is sent to the ECU. Hot wire uses a wire which has a voltage passed through it (similar to a light bulb filament). At low air speeds (low revs) the wire is cooled by a small amount. The ECU measures the voltage required to keep the wire at a preset temp and dials in fuel. At high air speeds (high revs) there is vastly more air flowing which cools the wire a lot more. Therefore a greater voltage is needed to keep the wire temp at the preset temp and a correspondingly greater amount of fuel is dialled in.

Tried to make that as easy as poss. Maybe someone else could produce fancy diagrams etc to illustrate the point.

TT
 

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Basically the AFM uses one of two methods, Flap type (e.g Bosch K Jetronic ala Pug 205 GTI) and Hot Wire type (errr...GTR) to measure the amount of incoming air into the engine and tell the ECU to dial in the appropriate fuel to maintain a preset mixture ratio. In basic terms the flap type AFM utilises a flap which displaces when the air rushes past it which in turn creates a voltage which is sent to the ECU. Hot wire uses a wire which has a voltage passed through it (similar to a light bulb filament). At low air speeds (low revs) the wire is cooled by a small amount. The ECU measures the voltage required to keep the wire at a preset temp and dials in fuel. At high air speeds (high revs) there is vastly more air flowing which cools the wire a lot more. Therefore a greater voltage is needed to keep the wire temp at the preset temp and a correspondingly greater amount of fuel is dialled in.

Tried to make that as easy as poss. Maybe someone else could produce fancy diagrams etc to illustrate the point.

TT
No need mate, I totally understood. Dont know why but anything to do with an engine and it sticks in my head, anything else (In one ear and out the other)
But I understand, thanks TT

If I force more fuel into the engine (Bigger fuel pump) then AFM will mix a bigger ratio of air and fuel yeah?
If a bigger fuel pump is fitted then does the AFM have to be updated in some way or does it automaticly do it?
 

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Discussion Starter #18
not had a problem since changing the fuel?! Car was really flying today as well, as i was giving it some to make sure the problem was well and truly gone.

Ill keep you guys updated
 

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If I force more fuel into the engine (Bigger fuel pump) then AFM will mix a bigger ratio of air and fuel yeah?
If a bigger fuel pump is fitted then does the AFM have to be updated in some way or does it automaticly do it?
I think i'm right in saying that the more fuel, boost etc you throw into the car, eventually there will be a weak link, in this case, the standard AFM's will max out.

Thats why people fit larger Z32 items.
 

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I think i'm right in saying that the more fuel, boost etc you throw into the car, eventually there will be a weak link, in this case, the standard AFM's will max out.

Thats why people fit larger Z32 items.
then what's with the Nismo 72mm AFMs that are said to be an upgrade? Hell, if it's just a filament upgrade then I'd rather go that route than have to replace my entire intake system. In theory it'd be swell to slap in some 80mm AFMs and then do all the piping and a new Apexi come kit to replace the ol' HKS mushrooms, but if the same can be achieved by simply swapping the AFMs, then that's just more money and less time towards my cam upgrade :)
 
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