Shiv Welcome back, is there any chance you might be working on VE Algorithm for the XEDE so some of us might be able to go speed Density and Remove the MAF?

 

Sweet! Fun stuff. Ok.. here's what you do...

You'd have to give up two of your analog inputs if you are running SMART. Both knock or AFR. If you are not running smart, then it's no problem when there are to that are unused. One input will be used for MAP voltage and the other for manifold air temp.

You can then remove the MAF sensor and wire up a 0-5v 3 bar map sensor in it's place. It will have 3 wires. One is for 5v. One is for Ground. One is the signal. That signal goes into AN0in.
Then wire up the temp sensor (make sure sensor is after the IC near the TB). One wire gets 5 volts. The other is the signal that goes to the XEDE's AN1in.

That's basically it for hardware work.

To set up the map, here's what you need to do:

For the Fuel table, go to "Edit map..." and change both the "input variable" and "load variable" from Freq0in to An0in (MAP signal). Set output variable "User #" (use whatever user 1-8 is free). Then change "Math Function" to Absolute Output 0-100%. What this all means is now the fuel table will be set up to translate the 0-5v MAP signal into a standard MAF freq signal that the stock ECU can understand. And the cells in the table are what you use to calibrate one into the other. Neat huh?

So how does the temp sensor come into play? Easy.. i'll tell ya!

Then set-up another table called "Temp Compensation" It only needs to be simple 2D table (just one rpm point is fine-- pick any number). Set-up the load variable to be An1in (intake temp signal). Set input variable to be that User # you picked in above. Set output variable to be Freq0out.

Anyone see where I'm going with this? Anyone want to take a shot at explain how the whole thing works based upon the info provided above!? Bueller? Bueller??

-shiv

 

I think I'm talking here in hijack mode. If you'd like to move these comments, that's fine.

Too bad Shiv the XEDE doesn't have any more 5V A/D inputs for MAP. Like every piece of good computer hardware, you run out somewhere. (National Instruments Boards anybody?) ...

Regardless, I can't say that I'm absolutely impressed with the Eddy Current Pulse (I forgot the special eddy current name for this) MAF sensors like the EVO has. The good points are MAFs allow one to put together an engine with a substantially different VE (i.e. EVO 2.3L stroker). Whereas MAPs require a pretty good idea of engine VE from the start.

MAFs like the EVO's are a restriction due to the honeycomb element. The honeycomb forces laminar air flow across the sensing element. However, the least invasive MAF sensors are I believe hot wire as in those employed in GMC and BMW autos. Has there been any talk Shiv, or actual implementations of the EVO/XEDE being able to use a Hot Wire system?

Thanks,
~j.

 

Hot wire implementation would be the same. Instead of MAP, we wire up a hotwire MAF. Same wiring and set-up. As for the factory MAF being a restriction, I disagree. If we are talking about a 600+hp application, sure. Anything less than that, then no, it is not a restriction by any means. We've demonstrated this before. As have our customers. The factory MAF has also been proven to be very repeatible and stable as far as its readings go. Even pushed to very high freq. If you want to change sensors, that's certainly possible given the ability to recalibrate for different MAF sensors in the XEDE software. But I think that excercise is largely acedemic for the vast majority of applications.

Shiv

 

i actually understand what your saying, my only question would be if you could have it all work while keeping the smart. Possibly updating the XEDE so it could accomodate additional analog inputs.

You've got the Customer base and products to corner the market if one of your selling points was the ability to eliminate the stock maf or even use a higher flowing GM maf.

 

We are out off inputs with the current XEDE. The processor isn't taxed but the basic I/O limits have been reached with the SMART system. The only solution, other than a complete redesign, is to run two XEDE's in series which would essentially double your I/Os. This would allow you to do all the usual SMART functions, MAP/MAF conversions, and directly drive two solenoids (boost control, nos, etc,.) In addition, there may be enough I/O to control the ACD system as well. But you'd have to fit 2 units behind the glovebox.

shiv

 

I'm going out on a respectful limb here; I ask in ignorance, bear with me. From what I understand you're saying, you are talking about total peak horsepower? I'm trying to understand from your practical knowledge what a "least-restricted" intake would do to the EVO, i.e. removing a honeycomb MAF and replacing it with a hot wire MAF, in terms of better driveability/racability.

Of course with the setup and design of the intake tract, we've got a 'nasty' turbo sitting in the middle of the tract where its spoolup performance greatly determines motor runup response.

Basically my ideas stem from the attitude of (for our racer folks) rolling hard on the gas, and my question now is if the EVO will be more "roll-on responsive" without a honeycomb MAF? Will the driver get better "feel" for the power output at hand because the EVO may have an easier time coming up on the power graph when it tries to gather more incoming air in a spoolup condition?

Thanks,
~j.

P.S. With all the extra processing power, can we bury an MP3 codec, and when the processor recognizes racy driving, can I have it play "Turbo Lover" out through my sound system?

 

I like the idea,

Reason i'm asking is i've had my AEM computer crap out rwicw leaving me stranded becasue of faulty software.

I would rather go with a fully integrated piggyback such as the XEDE w/ the smart i believe it's the only real way to go unless i would go MOTEC but thats way overkill for me at this point.

 

+1
Any ideas on using something other than a honeycomb MAF for better driveability vs. total peak HP?
~j.

 

I'm not sure I agree that the honeycomb MAF is compromising either driveability or power. At least not in applications below 550-600bhp. We can certainly get the XEDE to work with any MAF you want to use. But that's a custom job since it does require a lot of recalibration. Not something that you could do properly without a log of hours on a load-bearing dyno (going rpm by rpm, load by load).

 

How is closed loop fueling going to work w/o a MAF?

 

I think you might have to explain where you mean "closed" in reference the fuel loop?
I'm going to take a stab at your question as most of the times closed loop fueling means at what point does controlling computer allow information from an O2 sensor (narrow or wide) to dictate how to adjust the fueling to approach a desired A/F ratio.

The short answer is by replacing a MAF with a MAP, you're just calculating the air mass going into the motor a different way. The loop can be closed at the O2 sensor just like before.
Hope that helps.
~j.

 

I should have made my question a little bit clearer.

How is the XEDE going to deal w/ closed loop fueling w/o a MAF? Are we going to have to tune for close loop operation in our maps?

 

Couldn't you use the input from the stock boost solenoid as a free input? I think its PWOin?

 

oh ... I see what closed loop you're referring too. You're taking about the SMART system the XEDE has, which is a different (but similiar) closed-loop somewhat like the EVO's computer.

Yes ... you would have to somehow find a way to get two Analog inputs back. I think Shiv said not possible. Additionally, I don't know if the PWOin is actually an input? My impression (not actually dissected the system just yet) was the XEDE is an electronic boost controller, and it runs only a PWM (Pulse Width Modulator) output. Can that PWM Output be converted into an Analog Input? I don't know right at the moment.

Regards,
~j.