I'm no expert but VE is for "Volumetric Efficiency", which in an stock NA engine, is inherent to the engine geometry, design, etc. I don't see why you would want to go there unless you are ported or boosted. If fuel trims are out of whack, it is because the values on the tables don't match reality: MAF sensor vs MAF table, injector flow (which is dependent of fuel pressure as well as injector performance), etc.

One thing I remember from Kane's teaching the first day we ever spoke on the phone .. 'dont touch ve table ... dont touch ve table ... dont touch ve table'.

Correct. FI Motor's and ported motors will need to adjust the VE accordingly; but 99.9% of NA factory motor tuning will not require the VE table. However, since no two engines are built the same, sometimes it is needed.

thanks for releasing the video!

VE is changed whenever the way air enters or exists an engine is changed.

That is not as significant on our engines as all intakes and exhausts designed for our cars are no real benfet over stock so VE stays the same, put the same mods on an LSX and it makes a huge difference on VE

What mod makes a significant difference in VE on a NA RENESIS?

F'ing up the intake harmonic resonance features for one ...

In a positive way? Nothing really - maybe luck of the draw that you have a higher compression engine. The Renny is about dialed in on the VE front. You can muck it up pretty easy if you start jacking around with port opening times and all that.

LOL - Yup

So how do we want to go about doing this knowledge sharing? I would like to contribute and post images of some of my tune params (maf scale, injector scale, ignition timing) just so people have an idea of what range others are using, but we need a clean way to do this so that A. newbies dont just plug in these random values in their maps and assume all will be kosher, and B. people dont mix up S1 vs S2 map values.

I say you load up the knowledge gun. If someone wants to shoot himself/herself with it, that's a personal choice which should be based on the uncommon common sense.

Haha true, although there is a bit of morality that comes with hearing someone shot themselves in the foot, vs providing them a loaded gun w/o telling them its loaded and having them blow off a toe :lol2:

I would love ignition timing discussion, its still not very clear to me nor is it something you can dial in without EGT and a dyno, without those you know you either have it or not but cannot tell how much potential you are leaving untapped.

I absolutely agree. Except wouldn't EGT's really come into play when retarding timing? The only ignition timing that I play with per suggestion is up at the top end quadrant of the RPM/load band where the stock map tapers off to a flatline. At that point my timing is advanced to what is close to linear from the previous data points.

Without a dyno I just get the 'seat of the pants' assurance that the car isn't pulling back on the top end.

Can someone direct to where I can find info on adding OMP values and kicking on the fans earlier? I read these are quite simple with the COBB but so far I have really only been confident enough to mask a CEL with it. I have read alot of the other tuning threads but nothing seems "step by step". Did I miss something?

You can tune either fuel or timing by EGT just not both at the same time. At low loads there is basically a bell curve on EGT vs timing. At best timing EGT is lowest and on either side, advanced or retarded egt begins climbing unless you are way too advanced and EGT begins dropping with ECT climbing due to losses from knock.

At WOT EGT may not stop dropping because knock will take over, but you will notice the power dropping off. At that point you need to pull some timing or add some water before things get hairy.

You can do the same sort of curve with AFR and find best AFR at a set timing. The stock o2 sensor is pretty responsive with both AFR and EGT and both can be read with a cheap obd2 dongle and Torque.

What you really need to tune right is a good set of det phones, then everything else begins to fall into place.

I'll have to check when i leave work, but I see two entries in torque for EGT (EGT 1 and EGT 2). I've been using the catalyst temp bank pid just for casual exhaust temp monitoring.

I believe Kane said I am using some aggressive timing up top. No knocking but you raise a good point. I'll see if i can get some EGT data

On an NA Renesis you don't need to GAS about anything other than keeping it near Stoich/lean for low loads, EGT tuning by rotor is for WOT only. Tuning by a single combined AFR isn't too far off from just guessing ...

I'm glad someone brought up timing... I could really use some help in this area. as far as tuning goes can't we dial in our afr then take note of voltage & g/sec before and after timing changes to see trends and gains. when there is no longer a gain with voltage & g/sec you know you have pushed too far? ricer math at its finest

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I'm just going to stop using the word knock, because too many people take it to mean obvious audible knocking sounds. What I really mean is detonation, you know the stuff that can cause the audible knocking sounds.

How do you know if you have detonation without det phones? If you can hear it from the drivers seat at high RPM and WOT it's already too late. Also mild detonation at lower RPMs and loads sounds much more like a belt chirp than a recognizable knock.

Detonation is happening at higher rpms even on a stock engine/tune. It's the reason why Mazda nerfed timing at high rpms and put so much fuel in at high loads. You can get some power there, but the detonation gets worse! You can even get less detonation and more power by using less split (and sometimes less timing), but if your engine ever goes lean that's suicidal.

The trick with NA is to balance the power added advancing timing with the power lost into the coolant/oil from detonation.

If you can hear knock at high rpm/WOT then you are probably hearing the result of preignition. Yes this kills engines fast! Bad fuel, a bad tune, or any number of mechanical failures causing the engine to go lean can cause enough detonation to cause preignition given enough time at WOT.

Dashcommand monitors EGT, but is not nearly as responsive as it needs to be to actually discern anything with.

Also I know Kane explained it but why do we tune idle first? instead of last like most other cars.

Ah, noted. Other than a 'det phone' (never seen/used one) is there other means of diagnosing detonation/preignition (i assume that is what your knock box was designed for?)

I'll for sure post by trailing timing map when i get home, but here is my stock vs current timing map for the leading ignition

Base
https://www.rx8club.com/attachment.p...1&d=1403030955

New
https://www.rx8club.com/attachment.p...1&d=1403030955

Mine does not go any more than 35 on the leading map, 20 on the trailing

Yea I may back mine down a bit after Harlan gave me a scare with his speech lol ... not to mention we arent really even the hottest part of the summer which could only make matters worse I assume should I have some unnoticed det.

The tune that Kane had tested with me stepped up only 0.5 degree per 1 row post 6k@60% ... the posted videos used 1 degree per 1 row which is where i got my numbers from.

We do idle first, because we have to scale the MAF and Inj1 alone before the other injectors start messing up our readings.

I designed the knock box as a failsafe to cut fuel/ignition in the event things went overboard. When I started it I knew very little about knock on a rotary and mostly just the misinformation lurking on the forum, that project will continue, but I found something easier. I have an off the shelf setup that works as filtered det phones, it's very effective and costs about $100 to build, I highly recommend anyone tuning to build a set.



Leading can gain power, but you are adding detonation. At high RPM it isn't as big a problem, and NA it isn't that big a problem. The real threat is when the detonation heats up your plugs enough to cause preignition, then things go south fast.

That leading map doesn't look that aggressive, if you have good gas available you might be able to push it further. But really I can't recommend enough building your own det phones.

Trailing plugs exist to control detonation at high rpm. This is because of the way combustion happens in the chamber. The leading plug does most of the work, but the flame front moves forward much faster than it moves backwards. You end up with a pocket of unburnt air stretching from the trailing apex seal forward. If chamber pressure reaches the detonation limit of the fuel (there is also a time delay involved) before that pocket is burn you get detonation. If you can light that fuel first with the trailing plug then most of the pocket can be burnt and detonation can be reduced or avoided, alternately you can just pull timing until the peak pressure is less than the detonation limit of the fuel.

If you push more trailing timing (without effecting timing overall) then you can avoid some detonation. But because the trailing plug lives in an ultrarich environment, if the fuel mix goes lean it makes the trailing plug much more effective which has the same effect as advancing timing.

This is why Mazda has used 3 plugs per housing before for high rpm engines. It's to have better control of the trailing pocket and detonation. This is also why running less split means more power, but can also mean less safety.

Idle is tuned first because it's a known reference. Once you have it tuned everything else falls into place.