hi! from a newbie in canada. rb25det neo, in 240sx

[polemite]

well, i triple checked all my hose clamps, and vac connections. didn't find anything wrong there.

plugged in while not running and decided to try the vct test. didn't hear any click. unplugged and metered the connector, and i can watch it switching on and off. plugged it back in, but still didn't hear anything. started up the engine and tried it, wondering if there would be any difference, and if there would be any change to the sound of the engine, but didn't notice anything. but the test did come back with a live graph.

i moved on to double checking the timing- just on nistune. i haven't made a jumper to clamp my timing light on yet.
odd thing there was that at 600-650 the timing was reading 3. i tried moving the cas, and got no change on nistune, but i could hear the rpm moving up and down. i just dialed the cas back to where the rpm was right and locked it back in.

i could see good readings on all the other sensors.

at this point i could still get that hesitation if i opened the throttle by hand. didn't really know where else to go, so i shut it down and decided to build the offset bracket i need for the throttle cable (the plazmaman throttle cable tab is too far away from the throttle body for the s13 throttle cable).

once i had that figured out, i fired it back up to test out the throttle from inside the car.... and now all of a sudden, the hesitation was gone! so either, it healed itself, or pressing the throttle by hand is much too fast compared to using the pedal?

these ecu's do self learn right? i see i have the option to clear the self learn. should i do that now with all these new mods?

in any case, seems like i need a vct solenoid. either that or i've been trying to plug it in backwards. never thought of that till now. didn't feel like the connector was clicking on like it should.


*update* reading through the forums, i see i made a mistake plumbing in my boost sensor. it should be pre throttle body, and i have it on a barb from the plenum. this could have originally caused my bog.

watching back a video i took while blipping the throttle, my afr was idling at 14.2, and hitting 18 at the time i was letting off the throttle (around 4k) too lean, but should i really even worry about it at this point? i imaging actually driving is a more reliable test.

i noticed a guy on youtube claiming to do an auto tune feature, but i haven't found any info on that. anyone able to elaborate? the guy in the video doesn't describe what he's doing.

[PL]

Yeah you definitely need the boost sensor in the correct location or you can get some terrible problems just as you open the throttle. I learned this the hard way.

Yes they self learn but no real need to clear it. Just drive it. It's only a small trim anyway.

You won't see timing change in NIStune when you move the CAS. The ECU is relying on you setting the CAS to match what it's commanding. It has no absolute reference. So just set it to what you see in NIStune. If everything is running sweet (ie: good mixtures and idle speed = target idle in the ECU) then you should see 15 degrees. Getting it to sit nicely on 15 degrees can take a bit of fiddling. But the main thing is that you set the timing at what you read from NIStune - whether that's 3, 5, 10, 15, whatever.

PL

[polemite]

Excellent!

Thanks for letting me know. I feel like I’m on the right track. More updates to come. Sound clip too. The sinco manifold is pretty great.


Update* the vct wasn’t plugged in right. Had to contort my hands to get a good grip on it, wiggle and push, and it dropped on properly. Fires just fine from the active test now.
Spent today re routing the boost sensor line, cleaning up loose ends, and working on the exhaust.

[Matt]

VCT in a NEO ECU needs speed input > 1km/h to function properly

[polemite]

Today was the road test. Almost all is well...

It is over boosting. I have the tial mvs set up for 10psi, but it’s going well beyond.

I pressure tested with compressed air, and could hear a leak.

Bypassed the manual boost controller to eliminate that. Tightened up all clamps and the banjo bolt on the waste gate. I can hear it operate, but it doesn’t hold the pressure either. Do these things bleed off the boost signal as they operate? I would assume it should just hold open until I break the line open again. Shouldn’t close on its own and bleed air, right?


Road tested again, and it’s still hitting at least 16psi. Too much.

[PL]

I have seen ext WG's leak a bit - presumably around the shaft. There's no seal, so it probably makes sense. Int WG's are different - and they will usually seal 100%. So I wouldn't be too concerned about that.

But if you can supply enough air to make the WG just crack open then that's your effective min boost. Easy on IWG, bit harder to see on EWG (once it's on the car anyway).

Can also depend on how well your WG exits from the manifold. If it's not done properly you may find that you're running 25psi with a 14psi spring! Definitely seen that. My mate's S15 had a 14psi spring and we were going to bleed it up to around 20psi to tune it. But we ran it up and min boost was 25psi. It was a "tacked on" EWG so the plumbing wasn't good. He looked at me and said "well we'll just tune it on 25psi". So we did. That was years ago and it's still going!

PL

[polemite]

Ok, I won’t worry about the internal leak. But wow, that’s crazy about the spring not really being accurate. I guess I’ll have to try a lighter spring setup.

Thanks!

[PL]

It's only if the plumbing to the WG is poorly designed that you'll get that uncontrolled boost. Normally a 14 lb spring will give approx 14psi boost.

Google "wastegate priority". It's basically about ensuring that the exhaust gas has a nice easy path to the wastegate.

PL

[polemite]

Thanks once again. Makes sense.

I also got a really comprehensive response from tial today, confirming that the internal bypassing is normal, and that the spring ratings are not exactly accurate due to variances in exhaust back pressure. I take this to be along the same lines as wastegate priority.

[polemite]

Update-

Switched to the smallest spring (green) and it will hold 6-8 psi up to 6000rpm. Didn’t get to test much, but it seems to creep up to 12 above 6000rpm.

Difficult to test on the road though. Going pretty fast, and it is all happening pretty fast.

Any hope of tuning this in? I’m thinking it’s too small, right?

[polemite]

Are you guys sure about the timing procedure?
When I ran through it again the other day, the display on nistune was again stuck at 3. I could adjust up to 15 easily using the light alone. Very clear results. The only spot where the computer and the gun were the same, was when the timing mark was jumping around from like 3-4-7, and back.

I’m thinking I need to advance the timing...
https://www.hpacademy.com/forum/general ... ded-timing

[PL]

Just be sooooooper careful if you're playing with boost and not sure about timing. You'll break it very easily if you mess up. I'd recommend only loading it up long enough to get a feel for what's going on. If your timing is being reported at 3 degrees then set it to 3. It just means your idle speed is too high and the ECU is trying to bring it down by closing the idle air valve and also by retarding timing.

If your boost is OK most of the way but gets out of control up top then it usually means that the WG is too small and/or the WG plumbing isn't obeying the "WG Priority" rules.

What size turbo and WG did you have again?

PL

[polemite]

I’ve got the base idle down at 630-650, so definitely not too high.
The manual says to set it with the timing light only. Doesn’t say anything about comparing to consult, so people must have been doing it that way long before Nistune came along.

There’s also a chance that I missed something like a fault code not shown on the main page. Seems like they don’t just automatically come up. Something feels off about the number Nistune is reporting, and it could very well be my lack of experience with it.

Turbo is a gtx3071r gen 2 clone. .83 ar turbine housing.
Sinco manifold
38mm tial mvs
3” downpipe, 1.5” recirc waste gate tube, 3” exhaust no cat, no resonator, straight through muffler.
Plazmaman top half intake plenum
Gfb respons bov
R33 throttle body

[polemite]

well i have a bit of news to report. i had one of those, "i'm and idiot" moments. long story short, while triple checking my ignition timing, i found an ignition coil not fully plugged in. so i've been testing on 5 cylinders so far. and here i thought it felt sluggish because of the timing!

speaking of the timing though, i did go through and set it as per the manual instructions, rather than the nistune suggested method. i feel like the timing isn't getting reported and displayed until the rpm is up over ~700rpm or so. that's my observation at least. below that it just pegs at 3.

so, i was at 650rpm, and i set it for 14 to be on the safe side. we only have 94 octane pump gas up here. i think they have 98 in japan.

back out on the road, it obviously felt way way better. the boost held fairly steady to over 6000rpm this time, with only a short creep up to maybe 10psi in the last 400-600rpm before redline.

for now, this is acceptable for me. but i got some suggestions from both sinco and tial on how to improve control.

specifically from tial, switching to a dual port control setup. i'm also a little suspicious of the vacuum line i've got. feels a bit too soft. i'm going to try to find something firmer.

[PL]

Yeah I guess that WG is a bit on the small side. Should still be OK though if the plumbing is good.

I assume you're triggering the timing light from a spark plug lead fitted temporarily between no. 1 coil and the spark plug? That's the only reliable way to do it.

Assuming your light is triggering reliably, and the ECU is reporting 3 degrees, and you're seeing 14 at the crank then you're running 11 degrees advanced. Be very careful to listen for detonation because that's enough extra advance to put you in the danger zone. Yes it'll feel better. Until it doesn't.

PL