WTF is the diff, between a datalog of a pull and a scan tool recording of a pull?

My son bought this WRX ****-box that has a plethora of issues -some other kid's project/problems. I'm trying to help him work through the problems and we've found and fixed a bunch of things so far, it's running better and better, but still not right. I posted on the Suby Impreza forums (NASIOC) and they all want to see a datalog from this "Cobb Access Port", which appears to be a device for installing pre-made tunes, removing said tunes, and "seeing" what the sensors/actuators are doing. The screen on it is about 1"x1" so reading the screen real time is worthless. Apparently, you can download Cobb software from Cobb (my son did that) and then plug this Cobb device into your PC and upload datalogs into your PC...then make sense of them on the PC.

My son and I have done a few 1st gear pulls and "recorded" the entire, ~10 second event on my scan tool, then I posted every frame on NASIOC. These guys are telling me those frames of data are "useless"....I have to wonder if they're even looking at them!? What am *I* missing, here?

 

What's going on here?

 

Long and short... one is a little processed vs one not...

A data log is a data log. My experience with a tech 2 is it'll actually give snapshots of what is actually amiss. That being said, you have the raw data. If it's like how winaldl does it it is painful to look at. I used excel to plot everything with respect to run time and then it gets a lot clearer. But they both are looking at the same thing... however one may just be raw data... winaldl also does this sometimes. I'd be curious to know what they want to see data wise then go from there... post a data log is pretty damn vague and if you at least know what it's doing they should have an idea where to look for the issue first.

Edit: I know that my tech 2 can see things a little differently than say HP tuners too... but you can still access it so I really don't understand. I know certain sensors you're better off with a scope anyway. Digital triggers too slow to catch it.

 

Right? There is only one guy on there who has asked about specific sensors....the rest of the guys (kids?) are like, "YOUR SCAN TOOL IS USELESS!! SHOW US A DATALOG!!"

I keep telling them..."Here are the symptoms....what would you like to see. I can show you" ...but the crow on, about the scan tool. Just to make sure I wasn't being a total dumb ***, I posted over here to check. I actually asked at least three times, "what's the diff between the data my scan tool will show (after I've already posted frames from videos of pulls) and the data that would come from the "Cobb Access Port"....crickets, every time.

Also, and now I'm just bitching...but one of the guys asked me if I could see injector duty cycle. I told him that I can see injector milliseconds and convert that to duty cycle by dividing 60 by the RPM x2, to get the available time, then calc the percentage of the displayed time vs available time to get Duty cycle (%). I got laughed at for that one.

Thanks for replying.

 

Ah so they want a file to stare at. Even still... the scan tool is fine. Idk. People are dumb and I'm one of them most of the time so I'm useless. The duty cycle one cracks me up though.

 

LOL...well at the moment, I'm the dumbest person on NASIOC.

Read it HERE, if you feel like it. :-/

 

They want to see data at a sufficient sample rate that can be displayed graphically. Csv files can be easily shared and viewed with a log viewer tool. Snap shots with limited data and limited sample rate just aren't that helpful.

Here's a cool example log from the polar vortex we had a couple years back: https://datazap.me/u/tequilaboy/cold...5942-5934-5897

I marked a couple points of interest. You can zoom in/zoom out and turn signals on and off and manipulate display scaling.

This was not a Subaru, but the data was recorded with a Tactrix Open Port 2.0. The sample rate is not all that great here, and only logging a few signals stand alone to an SD card on the Open Port 2.0, but its enough to see what is going on. Note the temperatures and knock sum. I wouldn't have thought it would knock so much at -5 °F ambient. Note: this tune did have IAT based EBCS compensation to prevent over-boosting at low temperature, so I was curious to test at the extreme temperature (for SE Michigan).

Injector duty cycle is simple math if you know if the pw is calculated per rev or per 4 stroke cycle.

Deal with the Cobb AP, or get a Tactrix Open Port and use whatever open source tuning tools are popular with the Subaru crowd.

 

Hello Again,

I have followed the advice of a couple guys on this Corvette Forum who really believe in scanners and I bought a Snap On MT2500 and the 1320 ALDL Cable with everything. I have been very impressed that I am able to see the data on a couple of my OBD2 vehicles in great detail. The screen is not a lot bigger but it is a powerful tool in the hands of an experienced tuner like yourself. I am a newbie at data logging as well.

I read some of the Posts on that Subaru website and some of the guys don't sound like they are really knowledgeable about the Subaru fuel system details. I can't believe that you are supposed to drive around at below 30 mph until you "Get a Tune". I have never liked the Subaru car company as they copied a tried and true engine design and they still screwed it up. I am still a VW person versus a Subaru.

Don't take their criticisms to heart, they don't have any idea how to really help you it sounds. With your knowledge and the right tools it will be solved!

 

Hello Tom400CFI!

Could it be a defective KNOCK sensor that is pulling the timing back and messing everything up on your son's Subaru? Knock sensors do fail and when they do the power goes with them. To test them on a Corvette we suggest you tap your engine block or cylinder head with a metal wrench, if you tap loudly enough the timing will pull back and the idle will change.

Have you ever heard of J&S Electronics "Safeguard"? They are made mostly for Four cylinder Turbo charged engines. I have been waiting for them to make a box that will work on my C3. What that box can do is amazing. I see they are now making them for '99 and later Ford COP cars.

The amount of air going into the combustion process seems a bit low, have you checked to be sure the MAP sensor is working 100%? I understand that it has smaller cubic capacity engine but that number should be much higher with 11.4 psi of Boost I would guess. What is the fuel pressure doing as you accelerate at WOT? I wish you the very best in solving the Subaru issue with your Son! May your Son learn lots from you about cars and especially Corvettes!
My son just leaves his car for me to fix and takes mine. My daughter will help fix her car and I love her for it.

Best Regards,
Chris

 

Thanks guys. Tequilla boy, thanks for the visual example of the datalog. That does explain a lot.

Ctmcccloskey, Thanks for all the tips, no offense taken....I don't have love for suby's.

IHBD yeah, you're right about my tone. I even tried to NOT be that way...b/c I know how it looks when a newb comes on here and does that! And I've still gone and done it. I totally agree that the Cobb device is what those guys are familiar with and my son is trying to get his working. Right now he's waiting for a cord from Cobb, then it SHOULD work. That will be better for everyone. In the mean time, I have this scan tool.

I'm sticking with SnowBound. He'll actually be here (UT) in less than a month and hopefully we'll have the Cobb device up and running by then.