Bizarre Cruising Problem

[gt-ahhh!]

hello yes i have searched the forums

.33 gtst rb25det

.modified to ~220rwkw, 18psi.

.all supporting mods inc. toshi remap

last night the car developed a strange problem hesitating, stuttering, coughing low down in the range (up to 4000rpm). it felt similar to the car running out of fuel, or an air leak. checked both these things, cant rule out a small boost leak, but i am puzzled because once the turbo comes on boost the car runs fine, and still swallows the tarmac like it always has. even downshifting and booting again, the car works great as long as you keep it on boost.

it seems that whatever the problem is, boost fixes it.

to my understanding, that rules out ignition problems, since i figure they would get worse under high boost. (though im about to change the plugs). same goes with a boost leak, which would probably get much worse under high boost.

my old man seems to think it might be the fuel filter, a blockage of some sort. i guess maybe when it comes on boost it overcomes this blockage? another theory i have is the o2 sensor, though i have little understanding of them, it seems to be a common problem in my various searches through the forums.

any ideas?

i figure a fuel filter would be about $20, and an o2 sensor <$100 so ill prob change them if i cant figure it out soon.

cheers,

mitch

[Moodles2]

If you have the stock ECU (nistune'd or not), flip the R33 service manual ( http://www.importworkshop.com/nissanskyline.html ) to the self diagnosis section, code 55 is all good, anything else just look up the code and it should tell you what's the problem

[gt-ahhh!]

edit: car also seems to respond to quickly backing off and then getting back on throttle.

[and3_3]

I believe i had the same problem, i thought i was looking at new coils but i merely took the coil pack loom off and straightened it out a bit and it was fine!

Just check all your connections for crap and full connectivity.

[gt-ahhh!]

replacing the fuel filter made a massive improvement! wasnt overly difficult to do either, so ill def be doing that every 20k or so. the old one was filthy, no idea how old it was... potentially 100 000km.

still to change the plugs, cant locally source anything in a 7 heat range ffs!

[gt-ahhh!]

problem has re-emerged as soon as i got on the fway. hoping its the O2 sensor, and hoping i can actually get the one i need instead of a fkn vl one.

[W0rp3D]

problem has re-emerged as soon as i got on the fway. hoping its the O2 sensor, and hoping i can actually get the one i need instead of a fkn vl one.

Right HERE

[gt-ahhh!]

o2 sensor seemed to fix the problem, but it repeated randomly on the way home last night.

guess i will have to throw it on a dyno and get them to have a good look see.

[MotoMan]

im having the same issue... i was thinking it might be fuel pump dying.. feels like my car is running on five cylinders

[WHITEBEAST]

Hey, I have a issue with my RB26. After it warms up, or after a squirt. Once the cold air circuit closed loop has opened. It started off really intermittient. Now it is getting worse. Shutters/hunts and stalls. Started off happening on the highway where it would be driving fine untill it starts surging/misfiring, feels like ECU cuts ignition and fuel, and it stalls, restart/jump start then it will be fine for a little while. I managed to get consult plugged in, and logged data stated faulty Mass Air Flow Meter code## (mind you this could of been from past unplugging of sensor, from having to clean oil out of sensors with contact cleaner (Co2) was causing simuliar problem earliar to this) have now pulled off most of piping around turbos down to housing, now clean!. I can see a little puddle of really sluggy oil (amount of a 5c piece) in bottom of back turbo housing, was also a small amount in front housing (blowback from running 12 psi now maybe) installing a catch can this time. Front turbo shaft feels ok no oil around it, can't reach back turbo shaft or get any further visual inspection of it, apart from a slight amount of greasy old oil around outside of rear turbo. I am thinking it is either of many of things after been reading a few posts.

Faulty - Mass Air Flow Meter sensor/s (enough, was enough).

Faulty - Air Temperature sensor.

Faulty - O2 sensor

Faulty - CAS.

Faulty - TPS. (allways had odd idling 900-1200 rpm depending the outside temperature)

Faulty - Fuel pump (pressure).

To much oil in the system (intercooler, plenium, AAC valve, air regulator). - not fun to get at on a R32!

Turbo said enough, is enough.

Or maybe even a injector/s or even possibly a ECU giving up. If anyone can help to my cause it would be much appreciated.

Thanks WhiteBeast!

[gt-ahhh!]

i reset the ecu and it helped greatly, still did it once on the freeway. i have no idea, it seems totally random when it happens, the rest of the time the car goes hard. much better now though.

[cmoney]

Sounds like ur AFM could be starting to play up. Might just need cleaning properly. Mine did this initially as it was playing up intermittantly, & boosting did seem to help. But then i discovered that mine was completely f@#$%d 5 mins later lol. I reckon try this, as it does seem to emerge then disappear randomly.

[gt-ahhh!]

Sounds like ur AFM could be starting to play up. Might just need cleaning properly. Mine did this initially as it was playing up intermittantly, & boosting did seem to help. But then i discovered that mine was completely f@#$%d 5 mins later lol. I reckon try this, as it does seem to emerge then disappear randomly.

thanks i will take that on board. i just put in a z32 maybe 6 months ago, so itd be rather annoying if it was that.

[gt-ahhh!]

PROBLEM SOLVED!

vacuum leak!