Bizarre thirsty spot at 2800rpm, 13b NA 6port
 

Hey guys, curious about a bizarre thirsty spot at 2800 rpm, my auto-tune has figured out that it has to ramp up the injector timing around this area to keep me towards my target AFR's...

Anybody know what could be causing this? It's not where the 6ports are actuating (I currently have them disabled) and that would be 3800rpm anyways.

Could it be engine porting? Problems with the injectors or something?

Its a series 5 13b 6port, large street port.

The engine runs SOOOOO smooth, this is the smoothest rotary I've ever driven, so I'm almost not too concerned, but it just seems so odd to me that there's this ridge at 2800rpm.

https://www.rx7club.com/attachment.p...1&d=1404791176

Also curious as to how to remove un-needed rows? This base map was Aaron's from the writeup, but i dont need the rows for boost. Any way to remove the entire rows?

Thanks
~Geoff

Hi Geoff, I'm sure that they will ask you for a copy of your MSQ & Datalog.

--



Hello, if there is no problems, that is normal, different engines with different porting
flow different from each other in different rpm range, is the same as the otto engines
with modified cams, in the moment they kik-in, i have see larger increase of fuel
timing than you have there.

It also depends if 2800rpm is were the injector staging starts, imagine that you have
2 injectors running the engine, at that point they are alone so the time is higher,
after the 2 other injectors enter than you have more fuel, so the injector time goes
down.

Now, normally the staging is smooth if all the settings are correct, and the map should
also be more or less flat.

Can you give more details, like what primary and secondary injector size you are
using ?

How about timing ?..... do you also have a fast change in timing on that RPM range?

Your AFR table is also changing on the same RPM ?



Regards


.

My rx7 in a similar config had a similar VE table in that part.

Some sort of resonation of the intake system is my guess.

To answer the question about rescaling the VE table though...

All you need to do is change the numbers on the left side of the graph. That's basically it. Just click on the number and TunerStudio will pop up and ask you for the new value.

Even in an NA application, make the top bin something like 110KPA to compensate for when the atmospheric pressure is higher.

Of course, remember that changing the load axis will re-scale your table so you will need to retune the table.

If you tune with %baro you do not have to make the bins go to 110. Baro will be factored in that way and 0-100 will work no matter what the barometric pressure is.

Thanks for the excellent questions - It's really helped me to look at the tables and study how they relate to each other and how their shapes relate with the actual driving characteristic.

I'm thinking the culprit may very well be the timing table: 2500 to 2800 is right where the timing advances a significant degree.

Both primary and secondary injectors are 460cc Series 5 injectors.

I've attached the fuel table and timing table:

https://www.rx7club.com/attachment.p...1&d=1405934424


https://www.rx7club.com/attachment.p...1&d=1405934424

Hello,

Yes, for shore ignition will have effect on injection time, it will start to burn sooner or later,
and A/F will change, you can try to smooth that map (make it more round/soft).

Imagine that fast changes in IGN degree is like you running with abrupt change in
ground level, the engine is the same, it need more soft changes than you have in your IGN table

A/F
IGN
This tables interact with VE, you change one, you have to revise the VE,
and your VE probably is the last one to have the final tune, because it is
the more dependent of A/F and next IGN.

If you change A/F and/or IGN, VE will need some correction.


Can you post your MSQ file, or show in numbers your ignition table, also post in
numbers and 3D your Air-fuel table.


Regards
-

I've spent some time tweaking AFR values and smoothing in the ignition table based on info I found here:

Ignition Timing
https://www.rx7club.com/megasquirt-f...2/#post8544497

AFR
https://www.rx7club.com/naturally-as...y-afrs-714259/

I will re-visit my VE tables tomorrow with this new configuration and see what it comes up with. Already, after some tweaking and tuning today, its running way smoother low-to-mid range. Once I get some auto-tuning in with the new tables i'll post my MSQ

So the results of those new maps are: Amazing. the car drives better in every single way, more power through the entire range, consumes way less gas at cruise, and way smoother driving experience all around. She has no problem screaming past 7000rpm.

And still has a 2800rpm thirsty spot. I've also noticed a few other spots down way low, like a 1700rpm spot and maybe a 2100 rpm.

I'm noticing that if I move a bin to be directly on that spot, it seems to be able to accommodate these WAY better.

~Geoff