Help... Rb26 Keeps Sputtering

[stagea_1998]

really need some help with this one guys.
I've been reading about and scouring the net for solutions but i cant seem to find anything that's fixed it yet.

Ive got an autech stagea (260 RS)
and whats happening is ill be driving along all good, and sometimes randomly, but usually after ive been coasting in gear for a bit then go to accelerate there will be either no response from the throttle of it will try to rev up and start sputtering like crazy and blowing out black smoke for about 2-3 seconds after which it will come back and run fine for the next few minutes till it happens again for 2- 3 seconds then runs fine straight after. Odd.

so far few things I've tried based on what I've found on the forums from similar problems are:
new fuel pump, replaced fuel reg, replaced CAS, replaced ignition pack, new splitfire coil packs + changed spark plugs as well as plugging in a consult cable to check for fault codes, there were none

I'm really running out of ideas here guys the car other wise runs fine and isn't down on power at all so im really just scratching my head over this one

one other thing i should add is today i pulled off the BOV's because i noticed just last week that i was getting a bit of fluttering, if say i put my foot down to full throttle (WOT) then back off to about half throttle it would flutter. (not sure if thats related to the sputtering at all)
I pulled them off and set them up for a bench test, and under 20 psi i was getting a lot of leakage out of the recirc outlet on both valves, within about 3 or 4 seconds the pressure in the piping dropped right to zero

checked everywhere else and there were no other leaks from anywhere else.... surely that's not right?

[XGTRX]

Did you check the MAFs

[stagea_1998]

ohh yea sorry forgot to add that as well

first i tried re soldering the connector pins to the PCB (a common problem there of having dry joints) which made no difference
so then i bought another pair to try and nothing...no difference

[XGTRX]

Sound like over-fueling more than anything. If you suspect bovs then block them off and drive around for a week and see how you go.... How is you fuel economy..any fuel smell at any stage?

Edited July 27, 2013 by XGTRX

[stagea_1998]

sounds like a good idea but wouldn't blocking them cause the car to stall every time i pull up, blocking them wont cause any other running problems than that will it??

fuel economy is as per normal but in regards to over fueling the only sign of running rich is the black smoke clouds i get when it sputters and some extra blackened spark plugs.

causes for over fueling?..... bad injectors maybe?

will have a shot at running around with them blocked though and see what happens
cheers.

[XKLABA]

BOVs need positive pressure in the signal port, the 6mm hose off the top, to remain closed and the. When that drops or goes to vacuum the valve opens

Fluttering as you described is normal for a GTR, both mine do it

Give it a full service, all fluids and filters, it's hard to guess the problem over the Internet

[stagea_1998]

BOVs need positive pressure in the signal port, the 6mm hose off the top, to remain closed and the. When that drops or goes to vacuum the valve opens

Fluttering as you described is normal for a GTR, both mine do it

Give it a full service, all fluids and filters, it's hard to guess the problem over the Internet

yea i understand the concept of how they operate...just seemed odd that it was fluttering to me but if you reckon its normal then sweet...bit of peace of mind there, also seemed odd that when i set it up for a bench test with 20 PSI on both sides it was leaaking air out of the recirc outlet pretty quickly. went from 20 psi to 0 in about 4 seconds when i pulled stopped supplying air.

however....

update on the car.....seems to be sweet now

after i cleaned up the BOV's and absolutely drowned them in WD-40 it was still sputtering but after driving around for maybe 40 minutes it seemed to go away

been running fine for two days now cant believe it was as simple as that -_-

[XGTRX]

So what was the problem.

[stagea_1998]

Well it turned out to be the bovs either not closing all the way or maybe the plunger not being able to move freely enough

literally all I did was take them out and hit them with some wd-40 and so far so good, will probably look into replacing them still though

hope that helps anyone else with any similar issues

[XKLABA]

yea i understand the concept of how they operate...just seemed odd that it was fluttering to me but if you reckon its normal then sweet...bit of peace of mind there, also seemed odd that when i set it up for a bench test with 20 PSI on both sides it was leaking air out of the recirc outlet pretty quickly. went from 20 psi to 0 in about 4 seconds when i pulled stopped supplying air.

however....

update on the car.....seems to be sweet now

after i cleaned up the BOV's and absolutely drowned them in WD-40 it was still sputtering but after driving around for maybe 40 minutes it seemed to go away

been running fine for two days now cant believe it was as simple as that -_-

I wasn't sure if that was how you did it as it wasn't stated and that isn't right they should hold that fine

if i get it right i can make them flutter for about 10 seconds, something i do when i'm bored driving around

good to see it's sorted, on to enjoying it

your not in western sydney area by chance, i saw a nice white 260 parked at the shops where we get coffees

[stagea_1998]

yea exactly what i thought defiantly not meant to be doing that, ahh well ill pick up a pair of aftermarket replacements sometime next week just for the peace of mind that it wont come back, but do i really need to buy two, surely i cant just fit one and block the other off ?

hahaha i do the same thing about 10 seconds sometimes if im traveling up hill
seems to be holding boost much better now than it used to though by the way

nah no where near man im from down in Melbourne, they're starting to pop up more commonly around here now though but everytime i see one its like.... http://i.qkme.me/3paixf.jpg