I've spent the better part of 3 hours trying to find this information and im finally breaking down and starting this noobish thread. I'm genuinely sorry if this has been covered before but like I said, I tried.


Here's a basic breakdown of what i'm trying to figure out.

We bought a 95 RX7 with a t78 kit and Power FC already installed and tuned. The car drove and ran great with the tune that was on there when we bought it. Since that time the oil control rings have gone out so its rebuild time. While the motor is getting rebuilt we may or may not alter the ports, it all depends on whats in there currently. We also intend to turn the boost up to 15 psi from the 12 we are running now.


My main issue is that our engine builder/tuner is unfamiliar with the PowerFC. I'm trying to learn how to use the commander and be able to perform the tasks necessary to tune the car.


As of now I have a pretty solid understanding (I think) of what the maps correspond to but my issue is with the actual values on the table. IE what figures do N01 - N20 and P01 - P20 relate to. I would assume that one is load (boost/vaccuum) and one is RPM. If this is the case would rpm just be my rev limit (8100) divided by 20 etc?


All help is greatly appreciated. I don't need to know what should be adjusted and how, I just need to be able to alter what the tuner tells me to.

 

to do any in-depth tuning you need to get a datalogit. This will allow a laptop to interface with the PFC and access more settings. I would find someone that has a Datalogit in your area and start there. Not that your tuner can't tune a PFC, it would just take some getting use to. Best bet is to just take it to someone familiar with the PFC. I'm sure someone that is in your area or near will respond and tell you where you could go.

 

I agree. You really need the datalogit to effectively tune the car. Using the controller would be very tedious.

But to answer your questions n1 - n20 is rpms in 400rpm sections from 400 - 8000 rpm. P1- P20 is load, from vacuum up to full boost. With the stock scaling P20 is around 20 psi, but the stock map sensor will only read up to around 17.5 psi so without a different map scaling or map sensor you wouldn't be going into the higher rows.

The datalogit allows you to change the scaling and all the RPM points to whatever you want. It also allows a laptop to be tuned and additional inputs to be logged such as AFR's or EGT's. You can make many many many other adjustments with the datalogit that the commander just won't allow.

 

Thank you all for the input. I understand that tuning with the commander is going to be very tedious but more than likely the map will only need to be changed a very small amount. Up to this point, the map has been perfect and the only adjustments that would need to be made are between 12psi and 15psi.


As of now everything has been answered except for the increments that load changes by. Going to from P1 to P2, rpms increase by 400 but going from N1 to N2 pressure/vac will change by how much?



Thank you all again.



Youre exactly right. Basically the plan is for our tuner to tell me what to change and by how much and im going to input it in the PFC. He has the tuning knowledge and i'll have the knowledge to use the PFC's UI.

 

N1 to N20 are not linear throught the whole map so saying what they go by is irrelevant. N10-N11 is where it goes from vaccum to boost though. For 12 and 15 psi you are going to need to adjust from about row 15/16-18.

 

Buy a datalogit, save your map to disk, and post up here. Some datalogs of your old setup would have been nice too. Until then, nobody knows what kind of changes your tune needs. All you can do is speculate based on what you admit is limited knowledge. Without analyzing data logs, your tuner's recommendations won't be much more than "give it more fuel so the AFR is x"

Besides having no useful datalogging capability, with the Commander you can't easily read trailing split, you can't adjust injector staging much, half the accel enrichment/throttle response settings are not available, you can't tune air temperature correction, you can't calibrate the MAP sensor, you can't access the base map at all... Don't assume the previous owner's tune was any good either just because you "think" it's running right. I have seen lots of sloppy tunes by supposed professionals who have a lot more confidence than they have inside knowledge of tuning rotaries and PFC's.

The Commander alone is not appropriate for a single turbo FD. You can get away with it on a mildly modded car with stock twins but that's it. Depending what kind of map you have in there, with your single turbo setup you could throw enough fuel at it and pull enough timing (if you calculate split on paper) that it won't blow up. But you won't even realize how much better the car can run, how much more consistent the AFR's will be as the weather changes, with proper datalogging.

Let's say you get on a dyno and you read a peak knock count of 70 on the commander, which is often considered to be "true" knocking. How on earth are you going to know if it is in fact real knock or noisy "phantom knock" without a datalog of knock count vs throttle position vs boost vs rpm? How would your tuner know that without the proper equipment? Without a datalogit, how are you going to adjust your air temperature correction to account for colder weather later?

Please, rearrange your budget and buy the appropriate equipment to keep your car running reliably.

 

Perfect, thank you.

 

I completely agree with arghx. The datalogit will allow you so much more flexibility. The amount of time saved by using the datalogit will probably pay for itself with the first tune. It will also allow you to forever tune the car in the future with increased boost and engine modifications. The commander was never really truely meant to be used to tune a car, Apexi certified shops had software that allowed changes with a computer similar to the datalogit. Not only will your car be safer to tune using the datalogit, but drivability will also be able to be much improved by using it. Plus if you are really worried about the $200 the datalogit runs, then just sell it when you're done with it. the value of them hold really well and you should be able to get most your money back out.

Also even though the car runs well with the tune in it, unless its been put on a dyno, or logged on the street with the AFR's, and knock levels checked out, there is no telling if it is really a safe map. Once you rebuild it, and especially if you port it and run higher boost, the map that's currently in there may or may not be safe anymore. No engine ever uses the same tune. Even a simple rebuild can change the parameters enough to require retuning.

But as stated the P rows aren't linear. It should idle somewhere in the p3-p5 area depending on how much vacuum the car pulls, and p10 at sea level is 0 psi it then goes up "about" 1.5 psi per row from p10-p16 then from p16- p20 is goes up about 3 psi. these are rough estimates and you will find some go up more and some less.

So as a rough example:

ROW / PSI
P10 = 0
P11 = 1.5
P12 = 3
P13 = 4.5
P14 = 6
P15 = 7.5
P16 = 9
P17 = 12
P18 = 15
P19 = 18 (stock map sensor limit)
P20 = 21

Get the datalogit

 

the car has been on the dyno, AFR's are great. I'm not debating that the datalogit would be a better route, i'm just trying to get an idea of what im working with. Thanks all.