R33 Auto - Tune Question, Stock Ecu

[hardsteppa]

so r33 with basic usual mods. It's auto and I still have stock ecu - have found that it's average performance wise, until it hits 100k's, then it's like the tune comes alive and it starts pulling hard. Doesn't happen like that at any point below 100k, and I had a search but can't see this being discussed anywhere. Anyone know if this maybe something tuned into the stock ecu for overtaking ability or anything like that?

[sonicz]

Most likely your clutches are slipping and it takes that long to get a fully engaged grip under WOT. Every auto skyline I have driven that wasn't a fresh R34 has had bad slip. IMO they only last about 100k.

When is the last time you changed your transmission fluid and what did you use? Nulon Synthetic works best for me. I know this may sound stupid as hell to you but it has worked wonders on slipping skyline auto boxes for me. try draining out transmission fluid until you have just after the kink on the dipstick. Yes that is below the cold range and yes take the measurement with the car warmed up and running with the shifter to park.

[hardsteppa]

fluid is fresh as can be, I'm using Penrite full synth. Have a fairly decent B&M trans cooler on it too. I recently did a valve body upgrade (twice, cause one of the separator gaskets had a slight leak the first time) so it has well and truly been flushed out and fairly new fluid. It doe still flare a lot on the 2nd-3rd change though so you could be right, maybe the 3rd gear lockup engaging at around that speed?

[GTSBoy]

I would say that if it isn't the tranny slipping a bit, then it could simply be an accidental "tune" coming into play. You haven't said anything about the age or state of health of things like the fuel pump, but it is possible, especially if it is the original pump, that when you get up to ~100km/h in 3rd you're loading the engine up enough to start to drop the fuel pressure. The original maps are bloody rich, especially if you add boost. If the fuel pump can't keep up then it will lean itself off and start to make better power. It's good while it lasts, until it gets worse and burns something.

Perhaps it would be worth putting a pressure gauge on the fuel line and checking it out, just in case. The other option of course is a check with a wideband.

[sonicz]

Are you still running the stock ECU controlled boost controller by any chance? Have you monitored boost levels when this occurs to see if they rise?

I have a turbo Auto R33 as well can't say I've noticed anything like this though I'm happy for you to take a drive and see if you can learn anything.

[KiwiRS4T]

Definitely worth bypassing the boost controller with some form of T instead if you haven't already - there is a 2 stage boost in the auto - low and not quite so low.

[Trex]

100ks would roughly be about 6000rpm? Does it start to slow down around 130k's?

[hardsteppa]

thanks fellas, and I think gtsboy might have a possibility with the accidental tune bit too, it's just weird that if I leave it in 2nd and run it all the way to redline it won't come in with the same kick, only happens in drive and around 100k....on full throttle at that point busy watching the road but seems seems around 100 every time. Bit more background, there's 3in bellmouth dump/blitz exhaust, 100cell metal cat, fmic, apexi pod in custom airbox, 3in metal intake pipe, td05 turbo running off wastegate only at 13psi with greddy profec B for spool assist only - no duty cycle, exhaust cam retarded 2deg, tomei fuel pump, good state of tune with even comp across all cylinders, splitfires, injectors cleaned, iridium plugs. Safc neo being tuned at moment (which is why i'm now asking about the stock ecu tuning thing, covering all bases) and no bagging out the safc lol, it's doing exactly what I want at this stage, minor little touch ups on the afr...I can certainly see the limitations of it now after having played around with it firsthand but on the other hand am even more convinced it's good for minor tidying up, the low throttle/rpm has picked up nicely) with aem wideband gauge. Afr's are around 11-11.5 between 5500-6500 with 1% adjustment on the safc so nothing really needed there, maybe it is just the stock ecu hits the 'right' point then?

[Trex]

Take a vid from 80-120 and show us. Keen to know what you mean. I've spoken to a few people about the autos really coming alive after 5000rpm could be similar?