I have a question that has been confusing me. Maybe the info is out there but I haven't found it. If Stochiometric AFR is 14.7 why are these cars being tuned to 11 - 12? Is that to stay rich for a safety margin or is that a more ideal AFR for power on these cars?

 

Optimal power is around 12.5....but most on evom tune for 11.5 (for safety) and claim that the hp loss is small....

 

OK I figured the 11.* range was for safety. But I just assumed optimal power was closer to 14.7. But that was just an assumption as I am just begging to learn this.

 

Its great for everyone to have it in one location. Awesome clear write-up

 

when I said lower boost, I should of said around stock 19psi instead of 21+. If you lean the AFR's out to around 11.5 - 12 then you have to massively retard the timing unless you lower the boost. I just wasn't sure what combo people have found to be the best. Let it boost to around 22 (stock turbo) and retard the hell out of the timing, or keep it to around 19 but have higher timing #'s?

 

hmmmmm yeah thats an interesting question.

 

Stochiometric(14.7:1) AFR is for idle and low throttle positions/light engine load. Once boost comes on and/or engine load increases, AFR's must richen up.

CJ

 

Stochiometric(14.7:1) AFR is for idle and low throttle positions/light engine load. Once boost comes on and/or engine load increases, AFR's must richen up. Optimal safe AFR's in boost need to be around 11.5:1. If you were to lean the mixture out too far, you would run into detonation. This is why people tune for 11.0-12.0:1 AFR in boost/high engine load.

CJ

 

Eric great explanation...

I have two questions,

1) If I need to change my a/f in cell 5000 RPM and LOAD 220, I am going to change that particular cell and I was told the adjacent cells to the right and left for that particula RPM,, I also told change UP DOWN LEFT AND RIGHT... so what is the right way?

2) you tunning process talks about tuning at peak boost to the determined a/f ratien 11.5 in your case... well I am making the assumption that you know when you hit peak boost in 3rd gear because you are logging you boost with either a JDM MAP sensor? - my car has the useless USDM sensor, no boost gauge, can evoscan scan boost out of the UDSM sensor? or what other methods to you employ?

To recap, I am running 15.7 in closed loop, once I go in open loop i should tape down to my determined "redline" A/F 11.5 in your case and hold it there until redline. (this is for all intern a purposed the definition of, "my tune runs 11.5 @ redline"?

Thanks !


In regards to sharing roms, I think it would be also better to post screenshots of maps and highlight the changes? I am curious for example to see someone's tunes a/f map.

check out post #10 - is this what a tuned map should look like?
https://www.evolutionm.net/forums/sh...d.php?t=321629

 

anyone?

 

What I know.

USDM sensor is only good to 1 bar. JDM is good to 3.0 bar. Most people log boost with the JDM sensor. It is $125+shipping from mrfred. Then there are some changes you have to make with EcuFlash, just search and you can find it.

 

1 bar = 15 psi aprox... how lame. anyhow, can it u log from the usdm sensor in evoscan using the boost (MDP) check box?

I guess my question is for those who tune, how are you all logging boost to tune, specially on a dyno when a customer who doesn't have a JDM sensor comes in for a tune. Or is logging boost no necessary when tunning?

I wish eric would come online and answer my post also =)

 

No you can't log boost with the USDM sensor. Some dynos have a boost hookup that they can get your boost from. The problem is I have found that the accuracy of them varies a whole bunch.

You can also log boost with other devices. I believe Zeitronix and Innovate setups offer this functionality. TTP can speak to Zeitronix and others on here can speak about the Innovate setups.

Its good to log it to see exactly what boost you are running. Eyeballing the gauge is tough and even then a lot of the aftermarket gauges are way off.

 

-- you answered my question in the other thread "how to tune an evo !" thanks

 

Here are a few answers:

1. If you need to change your 5,000rpm and 220 load cell, yes, you would do that to change your afr at that particular load/rpm cell. Yes, you do want to change the areas around it as well, to make it "blend" in with the surrounding numbers. Basically, here is what I do: Once I have changed my map to run the afr's that I want to (And I am changing it all the damn time with the weather changes here), I have an excel spreadsheet that has virtually every map I have available to my 05 VIII, and have the Fuel Maps graphed out in a very detailed 3D graph. What I aim for is that when you look at the graph, it has a very good slope. What I mean is, when graphed out, your fuel map will look like the side of a mountain, literally. If my map looks like the rocky mountains, I smooth it out so it looks like more of a "hill" than a rocky mountain. The reason for this is so that the ECU doesn't have to make drastic changes from say when you jump from 5,000rpm 200 load to 220 load. The quicker more drastic changes your ecu makes the more prone to knock it seems to make the Evo's. You want very smooth transitions. So, in a nutshell, I would say yes, you always want to change the cells you need to, then as a last step, blend your numbers with the surrounding cells. Once that blending is done, do some more logging to make sure your AFR's are still in check.

2. If you have a wideband, or at least one you might be able to "borrow", you can still tune your car based on load numbers and paying particular atention to your Injector Duty cycles. You can continue to up the boost until your injector duty cycles get to a value you feel comfortable with. For example, i just recently tuned a XI with quite a few mods, and a 20G turbo. My car will still ars3rape it because I kept turning up the boost until his injectors hit low 90%. I simply do not want to go above that on duty cycle because you will be maxing out your injectors. Since I have bigger injectors than he does, I can run more boost than his car can.

Also, The load values logged do somewhat correspond to "boost". Basically, you can use (with a small grain of salt) your calculated load values (2Byte Load) to know where your are hitting max boost. Wherever your peak load is is where your max boost would be. Now, figuring out what it is in xxpsi might not be very accurate, but you can tune without a boost gage. You just might not know exactly what boost you are running, but, as long as you aren't running over 100% Injector Duty Cycles (Or close to), your AFR's are OK, and you aren't seeing knock, then you can get to a well tuned car.

Your 11.5 to redline, yes, thats what you can say/how you can do it. Me personally, just for sake of example, when I hit it at 2,000rpm on my car, I am running 13.5afr when the turbo spools to about 2psi, taper to 12.0 when the turbo is at about 20psi, then 11.8 to 27-28psi and keep 11.8 till redline. Now, this is a relatively high strung afr curve, and I have found that when the weather changes (Get's colder), the car goes leaner and I have to watch what I am doing.

Also, keep in mind to all you people that want to see "tuned" maps and rom's. There is another car in Charleston, two in particular that are very close to being the same, close enough where I can almost call them the same car. A value in one car's afr map at say 6,000rpm and 280 load is 11.9 generating an actual afr of 11.2. The other car, virtually the same mods, at 6,000rpm, 280 load value of 11.1 generates the same actual afr of 11.2.

Like what MalibuJack said, it's all about your particular car. You can look at other peoples maps just to get an idea of what they look like and how they are doing it, but you almost with utmost certainty cannot dump someone elses map into your car and expect it to do the same. One map will act differently on the same year & mod car than it will on another of the same year and same mods. That's just the way it is.

There is a reason why most of us guys on here that tune on a very frequent basis are a tad on the reluctant side of just "posting maps/rom's" for our cars. We fear someone not understanding that even if it is an identical duplicate car, the map in one car will not be the same as the other, even with all things identical, and just haphazardly dumping it into their car, and having something really bad happen. Then, who ultimately is responsible? Ignorance on the owner of the car? The person who posted the map/rom?

We all would love to help all of you, but at this point, ECUFlash has become so popular now that we simply cannot help the ton's of people that come in this forum. There is TONS of information out there, you just have to find it. Even still there are times where I spend upwards of an hour trying to find an old thread that has some information that I need in it. But, we will still try to help when we can and have time available. Don't be discouraged! Eventually someone will come along and get you the information you need.

Hope this helps at least a few out there.