Power Loss On Downshifts, Bouncing Idle And Slight Hesitation At Specific Rev Point -R34Gtt

[XGTRX]

I have an energy depolerizer from a vl brocky. It may help all your problems in one hit.

[Badgaz]

i'd say try a larger BOV that vents to atmosphere with a softer spring pressure....keep the airflow going in the one direction....feel sorry for you guys in Aussie with all your legal drama.

[Ben C34]

That will cause tune Issues with the afm though that will need addressing.

[Badgaz]

That will cause tune Issues with the afm though that will need addressing.

yeah but they'd be easier to fix. his mixtures will will be richer for a short time when he closed the throttle....could be sorted out whenever he wanted.

[XKLABA]

A dual stage BOV would be better, stage one plumb back stage two atmo, that way there is some air going back to AFM and some well not, the trick is tuning it to get the right amount

[rondofj]

Well took off dipstick and can smell fuel big time. Will be taking off fuel pressure regulator vacuum hoses to look for fuel later. Stay tuned..this could be it, a leaking reg.

[rondofj]

Theres 2 bloody regs/dampers on a neo though

[wolverine]

I have spare Nissan regs from R33's which I believe are identical.

[rondofj]

Thanks, is it better to get new though, never know when the used ones let go- will check if I can use 33 one on a 34- i think the 34 neo has 2 dampers n 1 reg

[iruvyouskyrine]

i think the 34 neo has 2 dampers n 1 reg

Correct

[hy_rpm]

If a fuel reg is bad or fuel related problem on a skyline not holding pressure

There is the pulsation damper on the fuel rail to check

Turn it off and check how far the screw on the damper is sticking out and leave it overnight

Check if it has gone in and moved if so the fuel pressure is leaking if not all good

You were complaining about the fuel economy and the tuner has already told you the o2 is getting lazy

If a bad o2 was stuck too lean every time in closed loop it would try to dump fuel in to try to make the mixtures right

Check if your o2 signal is fluctuating when warm

Should be swinging high and low every second

Also with the intake I would try to modify the existing one as moving the afm further or closer to the turbo will affect the tune

And your std bov may not be flowing enough air for that turbo so it will still suffer from reversion and the std bov will leak

[XKLABA]

The only way a fuel reg can dump fuel in manifold is through the vac/boost line, start car and pull line off and look, for enough fuel to cause these problems it will flow out at you

I have personally never seen a factory fuel reg go like that

[AngryRB]

If a fuel reg is bad or fuel related problem on a skyline not holding pressure

There is the pulsation damper on the fuel rail to check

Turn it off and check how far the screw on the damper is sticking out and leave it overnight

Check if it has gone in and moved if so the fuel pressure is leaking if not all good

You were complaining about the fuel economy and the tuner has already told you the o2 is getting lazy

If a bad o2 was stuck too lean every time in closed loop it would try to dump fuel in to try to make the mixtures right

Check if your o2 signal is fluctuating when warm

Should be swinging high and low every second

Also with the intake I would try to modify the existing one as moving the afm further or closer to the turbo will affect the tune

And your std bov may not be flowing enough air for that turbo so it will still suffer from reversion and the std bov will leak

so is the standard BOV still considered adequate for these size turbo's, eg GT30/GT35..

Ive seen aftermarket ones and they come with a range of springs, eg 6psi , so if using that then boosting under 6psi would give a shhhzutututu which might be a way around the legal

side for people that want that, but you'd still have some reversion is that right?

On a stock rubber intake, the BOV return is quite close to the turbo inlet, so maybe modify the intake pipe to mimick that, so the entry point is close to the inlet and theres

a couple of turns before the AFM is connected.

Edited August 7, 2014 by AngryRB

[Ben C34]

I'm still using a stock bov with a 3076. I crushed it to apply more spring pressure so it doesn't leak.

Previously had reversion issues, modified return angle in inlet pipe and it fixed it.

Was surprising as the return was angled slightly to the turbo previously but obviously not enough.

It's a very simple thing to change, angled nd is very likely the cause of Ron ' s issues.

Anywhere that welds ally can do it. And cheap. And quickly.

[rondofj]

The only way a fuel reg can dump fuel in manifold is through the vac/boost line, start car and pull line off and look, for enough fuel to cause these problems it will flow out at you

I have personally never seen a factory fuel reg go like that

thats exactly what I will be doing tomorrow morning - check for fuel in the reg and damper vacuum hoses. Hopefully I will find fuel and confirm a dead reg - can i use R33 reg on 34 /possibly wolverine's one or do I need a R34 one - wreckers or buy new? Hopefully no touch up tuning required, but how to check if its providing the req. fuel pressure under load - else it will lean out n go bang haha..

I do remember when DVS Jez had a go at my 'stock' car 3 years ago he mentioned the fuel pressure's playing funny and advised me to get a spare r34 reg, which I got thanks to Johnny, so the second time round I went up to Jez with the spare reg, we didnt end up fitting it cos it was alrite then.. Now I have to look for that little reg, dunno where I put it or if it still there lol..

And yes I use a stock 'crushed' bov like Ben C34 does.

Edited August 8, 2014 by rondofj

[Dose Pipe Sutututu]

^ lol that was soooooo long ago aye..

I have access to a hand held wideband, happy to spend a few hours diagnosing your car.. payment = beer

[rondofj]

no worries mate will hit you up if need be, let me test a few other bits over a couple weekends - fuel reg, iron out boost leaks, earths, new O2 sensor etc; I have decided not to get the wideband cos of extra costs of equipment itself, weld bung away from turbine housing, touching up tune etc..

Do u guys get ur NGK O2 sensors from repco/autobarn/bursons etc?

[Dose Pipe Sutututu]

^ just disable it and disconnect it..

[rondofj]

I still prefer to change it and keep it enabled as it was tuned with it - do any of the R34 NEO people use the r33 NGK O2 sensors with the plugs cut off and wires crimped together? NGK dont make a R34 one, rang em up. Else the universal PEC O2 sensor from Vulture Motorsport is what I got and its gone funny after just 3 years!

Edited August 8, 2014 by rondofj

[Dose Pipe Sutututu]

Noone tunes with the o2 on