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please help vacume problem!!!

J

jonny b

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well guys,i put a fmic and dump valve in the car at the weekend,but now when im driving and i put in the clutch or put the car in neutral when the car is still moving it cuts out,,,i presume its a vacume leak??what would ye recomend to put around the ends of the pipes to seal them....[gasket sealer??].thanks in advance all help appreicated.
 

Yakozan

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Is a dump valve the same thing as an Athmospheric blow-off valve?
If it is, I've found the problem :)
S15 doesn't lika atmo venting BOVs very much and they usually cause the symptoms you're describing. Get a recirc kit for the BOV or refit the stock one and the problem should be gone.
 
J

jonny b

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ya a dump valve is the same thing as an atmospheric one,cheers ill try that thanks.
 
J

jonny b

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ya changed it there and solved the problem..thanks yakozan your a genius,,!!
 
K

krisrt

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Is a dump valve the same thing as an Athmospheric blow-off valve?
If it is, I've found the problem :)
S15 doesn't lika atmo venting BOVs very much and they usually cause the symptoms you're describing. Get a recirc kit for the BOV or refit the stock one and the problem should be gone.
does the s15 still not like atmospheric blow off valves even if their double piston ones?
 

DeanS15

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itll run ok with twin piston bov's but will over fuel and pop quite a lot from the exhaust.
 
T

Trepidge

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mount you afm on the drivers side piping of your intercooler and the bov on the hotpipe and youll be able to vent to the atmosphere, this gets rid of a lot of high idling problems with bigger afm's to
 
T

Trepidge

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you would have to make up custom piping on your intercooler but youd mount the afm, a z32 would be more suited with the wider diametre, on the piping after the front mount and before the intake plenum, then none of the air being vented by the bov would be read by the afm, and the engine wont over fuel
 

Yakozan

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That might improve things, but I don't it's as good as a recirc valve.
The AFM is positioned close to the filter as it measures the volume of air entering the pipe going to the turbo. The ECU then calculates the amount of fuel it needs.

By moving the AFM to other side of the IC, the amount of air measured will be less because of the air being colder. The air will not be the same mass as the density is higher. This would cause the ECU to calculate the air going to the turbo wrongly.

I have no idea how much this would effect the fueling. Maybe it's hardly noticable.

let me know if I'm wrong as I'm just trying to figure out possible problems with limited technical knowledge :)
 
T

Trepidge

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I didnt know this yakozan, I dont have this mod done so I cant admit it hasnt any flaws, read about it over in the nissansilva.com forums,
a few ppl run it over there to deal with racing revs caused by air turbulence between the turbo and the afm,
but if you're willing to go this far to vent to the atmosphere the engine should run considerable better than venting after the afm, personally i just recir,
there is a device out by hks, i donno is it just for their atmosphere bov's its called the EID's (electonic idle stabilizer), u wire it into the ecu and it supposily sorts out the over fueling issue with venting bov's
 

Yakozan

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Don't take my post as fact as I'm merely exploring my technical brainside regarding this :)

I could be wrong. A MSE in automotive engineering should be able to shed some light on this. To bad they're pretty rare on internet forums :wack:
 
J

jonny b

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yakozan@ your correct,but i kinda like the popping out of the exhaust due to the over fueling!!!
trepidge@ ya my mate with a 200sx has one of these edi,s not cheap tho
and what part of mayo ya from??
 
T

Trepidge

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Originally Posted by Yakozan
A MSE in automotive engineering should be able to shed some light on this. To bad they're pretty rare on internet forums :wack:
:D

Originally Posted by jonny b
and what part of mayo ya from??
im in castlebar m8
 
K

krisrt

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is this what id need if i wanted to vent atmosphericaly?

"The HKS FCD is an electronic device developed to properly raise the factory fuel cut level on factory turbocharged vehicles. As modifications are made to optimize engine performance, the factory fuel cut is often triggered by higher boost levels which activate a fuel delivery cut-off as a failsafe procedure. Symptoms of fuel cut are hesitation, bogging, and/or illumination of diagnostic indicators."

so basically the engine cut out switch is causing it to over fuel?
http://www.hksusa.com/products/?id=2175
 

DeanS15

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no way, the fcd isnt needed util you start raising the boost levels but if you get a custom remap they should remove the fuel cut anyway so you wouldnt need this.

to run a dump valve as i said it would have to be a twin piston one, even then if you dip the clutch at high revs it will try and die if you dont give the throttle a litte tap. re-circing gets rid of all these problems but also the sounds go with it......
 
T

Trepidge

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HKS EIDS Electronic Idle Stabilizer - http://www.rhdjapan.com/jdm-low/HKS-EIDS-Electronic-Idle-Stabilizer-9831

The HKS EIDS has been developed to buffer dramatic airflow meter signal fluctuations. By buffering these fluctuations the EIDS prevents engine stalling or stumbling associated with sudden imbalances in air/fuel ratio of airflow meter-equipped vehicles that utilize atmosphere venting blow-off valves.
This might work for you who want to vent.
 
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