I am trying to raise the rev limiter but from revving it in neutral, and datalogging on the spot (no WOT runs on the street since my laptop has no battery), the fuel cut is actually 5948 RPMs. I suspected something was off because you know how our Tachometers are off? To go to 6500 you actually need to go to around 6800-6900 on the tach.

Well because of the Z33 6-speed tranny I have no speed sensor. Maybe that affects it? Even when driving around, the rev limiter feels very cut short, it makes sense that my cut is around 5950 because it seems to kick in around 6300-6400 on the tach. Ever seen anything like that? I have a 95 5-5speed Fed spec ECU, and like I said no speed sensor at all.

Because of my cams, the car is probably peaking around 6200-6400 or so. So the ECU is actually cutting the fuel BEFORE my power peaks! Feels very cut short.

I dont want to rush this and I want to understand it not to blow the motor. Like I said I have the WB hooked up and it runs a little on the rich side which I like since its safer. At any RPMs it will always be between 12.5:1 and 12.9:1.

The I/J input duration reads 13.4 ms at 5948 BTW. Those are 3.5 270 cc injectors (3.0 bar), but fuel pressure is at 50 psi so they are more like 330 cc. I could simply add 14.0 ms (a little extra to be safe, since I am probably peaking AFTER hence need a little more fuel).

So I need to raise the rev limiter to around 7000. My idea is a soft cut (i.e gradually pulling fuel from 7000 to 7300 or so). Ive followed DandyMax's writeup and it says to use the I/J Adj map. And it says it uses 50 rpm increments, but there is only a box for each 500. That doesnt sound right. There is obviously something I missed.

How can I start adding, say 14.0 ms at 5900 or 5950 exactly?

 

Add 14.0 at 6000 or 6050 if you cut is at 5950.

I don't see how it is at 5950 tho. Log it and show me the pic if you don't mind. Let it bounce off the revlimit for like 3-5 seconds.

 

It's strange, the limiter being that low. To do the rev limiter it's better to be in gear so you have an actual load on the car though. I wouldn't as a rule recommend doing it in neutral.

And IMO you don't need to add 14ms, if you're already at 12.x AFR at 5948 then all you need to enter is 13.4 minus whatever your input duration is AFTER the stock limiter (let's call this number X, it will probably be about 12.x) Study the screen shots in the writeup, and the example I/J map I gave, particularly the input/output duration lines before/after the cut.

To get to 50 rpm intervals, use the change scale button and then type in new rpm points, you don't have to use the default (every 500).

As for the rev limiter, I'd suggest adding "X" in at around 100 rpms, maybe 50, before the stock cut. So at 5850 or 5900. It's safer than creating a small lean spot after the stock limiter and (for the cars I've tuned) seems to produce a smoother result.

Also, if you used the AutoTune to get your AFR dialed in elsewhere, and you're happy with it, then turn that feature off while you do the rev limit. I'd leave it off too once I got the tune in place, no need to have it continually adjusting on you. If you add a mod or a change and need to retune then use it again at that point.

 

The autotune will continue to apply the same AF after the stock rev limiter?

Why? Once I have succesfully advanced the rev limit all I need to watch out for is the AFR right? As long as the AFR stays in the 12s - if it leans out a bit at the stock rev limit will I see it on the WB while running the car? Just a slit second?

Right now I cant ride around with the laptop its gotta be plugged into a wall. Best I can do is on the lift so its actually driving the wheels, but not a load AKA on the street pulling the weight of the car.

My point is that with the aftermarket cams set to immitate VTCs at full retard, and the short ram 2k2 intake (like krismax), I am definately peaking past 5950. It has to be 6200-6300 or so. So I need to add perhaps a little more. The worst it can do is cause me to run rich after, which the Autotune will take care of. Does the autotune AF override whatever additional fuel I add when raising the rev limit?

 

It will aim for whatever target you set, BUT if it adjusts cells on either side of the stock rev limit transition, it might mess it up a bit/make it rough. That area can sometimes be tricky to get dialed in.



It's theoretically possible the fueling may be a bit different under WOT in gear vs neutral, depending on how the ECU is set up. On the Maxima it may be the same AFR at neutral, I'm not sure as I don't recall what it is up around 6500. It might not be a big difference for you, or you could find you've got it nice and smoothly dialed in neutral only to have it react differently at the cut point in say 3rd gear with lots of load and much slower engine acceleration. I guess it's not a big deal to try it in neutral first.



See above regarding the autotune. Don't forget that the stock ECU puts out a small pulse post-cut so you don't even need the full 13.4 right at/after the cut point if that PW is already getting you mid 12 AFR's. If you add 14 it's actually going to be closer to 15 ms. My power peak was a few hundred rpm after the stock cut but I still matched what AFR I had right before the cut (around 13.0 AFR). If you can match the before/immediately after closely it will help the smoothness of the transition. It won't hurt you to run 14 if you're determined too obviously but I really doubt you'll need that much, especially at 50 psi.

 

Well it looks like I was wrong the rev limit is around 6500-6550 if you really romp on it which I dont like to do in neutral. But now the duration sometimes goes up to 28 ms Ive even seen 35 ms (for a split second). Even though I only add 12.0 from 6400 up. There are some spikes where it goes above 20 ms. But even when it spiked to 28 & 35 ms the AF was still above 10 (10.3-10.6 or so).

Does this have anything to do with setting the injector size into the EU. I wrote in FROM 259 cc TO 330 cc since fuel pressure is at 50 psi. Should I write in 259cc to 270 cc instead, regardless of fuel pressure?

 

You shouldn't have to set the injector size

Just go buy a DC-AC power inverter for your car/laptop and do some road tuning... get a load on that engine.

 

Will try on the lift in higher gear first. Thatll be some load already.

 

That shouldn't be happening, but where is the spike for how long etc, - I need to see a log + em2 file. 100% DC (ie injectors static) at 6500 rpm is only like 18.x ms.

Leave the scaling boxes zeroed. For one you're talking a small injector size difference and for two, it's easier and less complicated to just adjust PW's directly in the map, without adding a scaling factor in to the mix.

 

These work well...

http://www.powerstream.com/dc6.htm