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

[rondofj]

Yeh that was the only mod, block off bov after tune - and yes they don't bloody know what the problem is lol..

Edited August 5, 2014 by rondofj

[XGTRX]

It can still get reversion with the BOV blocked, when you shut the throttle the air built up by the turbo has to go somewhere and with no where else to go it goes backwards through the turbo to the AFM

That could also be causing and increasing the hesitation between gears

Then this.^^^^^^^^^^^^^^^

Unblock it.

[rondofj]

Same deal unblocked. That is why it was blocked- to test it

[XGTRX]

As XKLABA said this will only add to the problem so unblock it and then fault find because obviously the bov is not the problem.

[Badgaz]

Larger bov required? is this why other cars utilize flapper type afms?

Edited August 5, 2014 by Badgaz

[GTSBoy]

Actually, at this point, going back to the first post in thread....I want to know what Ron meant by "jumps down 5 or 6 cells". By this I mean......down as in down the screen (which is an increase in load on a PFC, yes?) or down as in less load.

And, can we see photos of the BOV return location at the turbo intake please?

[wolverine]

BOV return looks ok for the record. I doubt given the bend in the intake pipe and the location and angle of BOV return this is causing any issues.

A lot of smack being spoken about the tuner with many of you having nfi.

[Ben C34]

My bov return was on a similar angle and caused issues untill I changed it to approx 45 degree angle pointing straight at the compressor. This made a huge improvement.

Afm's are very sensitive.

The tuner talk is obviously going to happen, seeing as the car isn't running right and they can't see why or fix it. That would be extremely frustrating for Ron.

For the record you have no idea if it has been tuned well , just the same as guys that are suggesting it could be the tunes fault don't know either. The high fuel consumption certainly suggests it's not an ideal tune in the cruise areas don't you think?

[XKLABA]

I know with the GTRs when you change from rubber intake to alloy ones with AFMs still in play they tend to get reversion even if they are exactly as per factory, something to do with the ribs in the rubber pipes regulating the air speeds

AFMs are very sensitive to even very small changes and as Ben said the return should be pointed at the compressor wheel, it helps the air circulate through the turbo to the BOV and around again instead of backing up though the AFM

A blocked BOV will give the same result as a open atom BOV as the already metered air passes back through it telling the ECU it has air going into the motor as AFMs don't know which way air is flowing only how much is passing through it

You need to get someone to watch the AFM map trace as you drive and see what it does

[scotty nm35]

You need to get someone to watch the AFM map trace as you drive and see what it does

This ^^

I think we discussed this already, about a year ago... And I gave up on it. AFM's can read up to 1 volt of reverse flow.

What I don't understand is how the tuner can't work out what's going on...

[rondofj]

GTSBoy yes the map tracer leaps down/south towards the higher load areas- literally jumps 5-6 cells-- r&r basically

[rondofj]

My intake again - the black rubber breather hose on left from cam cover wraps under intake pipe before curling over it to the joiner/entry, courtesy of JEM's 3rd party fabricators

[Dose Pipe Sutututu]

GTSBoy yes the map tracer leaps down/south towards the higher load areas- literally jumps 5-6 cells-- r&r basically

No such thing, it jumps because the ECU is interpreting load not going into R&R

[rondofj]

Scotty, the tuner says that at that point the ecu is dumping tons of fuel and retarding the timing like a mofo, this problem is not intermittent but constant, hence he decided the afm is ok- said to look at the entry angle of the bov return, relocating afm etc- but I doubt this would solve the issue- with Nistune and same all else this problem didnt exist- he said filters in Nistune mask the problem out- Im like really..

My cars been running rough again lately with O2 feedback off- do I disconnect the O2 plug too ?? cos the powerfc is still reading the sensor voltage and its variable volts with throttle input.

[Badgaz]

i think what he was meaning was that it will go Richer and Retard timing the further down the load points anyway....

[Ben C34]

Should have kept the nistune....

[rondofj]

Yavuz saw it jump and thats when he was convinced theres a big problem- he said that its dumping fuel n retarding timing at that point.

Yesterday I unplugged the z32 and it wouldnt even start- just cough cough and die lol

Edited August 5, 2014 by rondofj

[Ben C34]

Change the bov return angle then.

[Dose Pipe Sutututu]

Or get a MAP based ECU and sell your Z32, sell your BOV

[AngryRB]

My intake again - the black rubber breather hose on left from cam cover wraps under intake pipe before curling over it to the joiner/entry, courtesy of JEM's 3rd party fabricators ImageUploadedBySAU Community1407278665.866575.jpg

That hose looks like its not a good fit and the pipe even looks oval shaped?