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Datalogging 101

dyn085

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#1
I haven't seen a 'How To' on this, so I thought I would create one. If there is then feel free to bin it, admin.

Note-This is not meant to supersede any recommendations from your tuner, so if they tell you anything different then definitely defer to the pro's. This is an accumulation of information that I never really thought about posting until a buddy of mine asked me to look at his logs and I realized that he had no clue whatsoever of what he was doing outside of pressing the center button on the AP3 and accelerator/brake. A lot of this is over-analyzed from repeated trial and error of trying to collect the most accurate info for my car to be tuned off of, and for me to make legitimate comparisons with.

Believe it or not, datalogging your car starts well before you get in. You may not be as anal-retentive as me, but the goal here is to minimize the number of variables that will affect your pull so that you can get a clean set of logs that are consistent enough to be compared and relied on. The cleaner your logs, the better your tuner can do magic, and the better your vehicle will perform in the long run.

Note-It is a good idea to check your plug gaps before beginning or if you're currently having issues. Obviously this doesn't need to be done every time, just once before getting serious about logging. OEM gap is 0.031", though I gap mine at 0.026-0.028" due to boost levels. If your tuner gives you a recommendation then I would use that.

1. Ensure your AP3 is up-to-date and the applicable tune for the mechanical setup is loaded. KAM/ECU reset if applicable.
2. Ensure your car is either loaded as you would normally drive it or empty. It's ok in either direction, but you don't want to compare one set of logs where your car was empty against another set of logs where you happened to have 200 pounds of groceries in the hatch.
3. Fuel tank full. This isn't a huge deal, but gasoline weighs 6 pounds per gallon and that gives you around 72 pounds worth of difference from E to F. Log an empty tank in an empty car and compare it to having the tank full with the above-stated groceries...I'm sure you see how this compounds.
4. Verify OAR is at -1. If it isn't, do not log-plain and simple. The FiST adjusts really quickly, but if you aren't at -1 then you need to get it there first. Read: You-re-using-an-inferior-fuel...
5. Setup or verify (if necessary) the parameters you are going to log in the datalogging. Nothing sucks more than driving out 45 minutes, collecting logs, 45 minutes back home, just to open your newly acquired data and find out you've only logged data to make an intake comparison. Trust. Me. I'm not going to tell you what you should be logging as that may be dependent on the situation and/or pro tuner that you're using.
6. Set up your gauges as you see fit. In the beginning stages of tuning I only monitored AFR during a pull to verify that I didn't go lean, but after a while I began only monitoring my weakest cylinders ignition corrections. On the way to the road I monitor my six-gauge with AFR, oil temp, and all four ignition corrections. If you keep your monitors to only parameters that are being logged then it should not affect your logging capacity, but you'll want to try and collect a log (not necessarily a full-pull) just to make sure that whatever gauges you're viewing don't exceed the number of values the AP3 can log in conjunction with your established parameters.

Ok, so you're pretty much ready to go. Where are we going?

Ideally, all logging would be done at the racetrack where you could reach the speeds you're going to be reaching. For this discussion we're going to assume you're not, and will discuss a few things that you should at least take into consideration. This is largely a compromise though, so you want to find the best road possible based on where you live and within your convenience.

1. Obviously you are going to need a long enough stretch of road that you can complete a full third-gear pull from roughly 2500 rpm up to redline, along with the appropriate stopping distance. If possible, having a stretch of road that's long enough to remove any heatsoak before turning around is optimal.
2. A road that is as flat as possible. Incline/decline will have an effect on the performance and, in-turn, the data. If you don't have the most perfectly flat piece of glass to drive on, collect data in both directions.
3. A road that is as smooth as possible. Road imperfections and texture will have an effect on the data if they're severe enough so, if possible, find a place that's newly paved.
4. Traffic is obviously a consideration. The fewer, the better, and in a worst-case scenario you can always opt to collect during late night/early morning.

Your car is ready and you're at your road with great conditions for some logging. Now what?

This is the easy part. If you've prepped accordingly, you should be able to roll up, collect your data, and get back to the house. Here is a step-by-step breakdown of my CDO while logging, and you can adjust it to your needs.

1. I know I said you're at your road, but on the way to the datalogging road I try to get a few mid/heavy throttle pulls en-route, simply to make the KAM aware of what's going to be occurring. Maybe it helps, maybe nah.
2. When I arrive to my road I always complete a pass in one direction to make sure that it's clear of obstacles, debris, police, bystanders, etc. One more than the others, but basically it's just a 'route-recon' for any ex-military types. Because I use this one specific road I know where I'm turning around to start my run, but it will take trial and error your first couple of times to get your distance and turnaround points. I set my cruise-control to 60 mph because I'll use it later.
3. Once I have the space needed, I will make my turn-around and begin on my downwind pass. I get my car into third gear and stabilize rpm's around 2500-ish.
4. Press the center button on the AP3.
5. You don't necessarily have to, but I wait until my gauge reappears to start the pull. Floor the accelerator until redline.
6. Remove foot from accelerator.
7. Press the center button again to stop the log.
8. Return to 'normal' speed and drive normally for a few minutes to shed heatsoak, especially if you're on the OEM FMIC.

Repeat as required until you have the number of logs you wish to collect. I generally collect three simply because after the third I'm already going in the home direction.

So, that's basically it. If you're consistent and have a good road/weather, your logs should be pretty consistent. Head home and download your data, make sure it's legit before emailing it to your tuner, plug it into V-Dyno, upload it to datazap.me and over-analyze it for hours...whatever floats your boat.

I hope this helps.
 


Kip2MyLou

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#3
Agreed with the sticky. I've never datalogged and to be honest had no idea how to. And I bought my AP from Mountune so I would like to do some datalogging for Randy to work his magic, and now I can! Thanks man!
 


rexdriver85

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#4
Great follow up to your other article about false knock. This will help the community a lot as it grows! [emoji106][emoji106]
 


iso100

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#5
It's worth mentioning that some tuners want a full 25 variables logged in the logs, so you won't be able to run a 6-gauge monitor during the run. For this I switch to a 2-gauge monitor view when logging and then switch back afterwards.
 


westcoaST

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#6
Randy at Mountune has a specific set of parameters he wants logged. I found these on the other forum, and confirmed them with him. One thing not mentioned directly, but alluded to was qualify of gas. Specifically ask your tuner which brand of gas he recommends. In my case, he wanted me to use Arco and Propel. He also does not want more than one or two runs. Do not shift into 4th at the end of your third gear run, before you stop datalogging, and I recommend having ESC off before a pull. I did my pulls a couple of blocks away from my home at 3:30 A.M in the morning on a flat, two lane road. going one way, then back the other way. Practice makes perfect. I could only have one gauge showing boost since Randy had a full set of data to log. Try to log before you actually log because you may need to reduce the number of gauges being displayed. Randy wanted the 3rd gear pull to start 10 seconds after hitting less than 2000 RPMs, and end at redline.

Get a copy of VDyno (Virtual dyno). Its free, but you will need to input your variables into a profile. The correct data is floating around the other site, and also, I believe on this site. Randy and I worked on my e40 tune. I also run a Cobb stage tune 91 octane. Once everything is finalized, I plan on getting a dynotune.
 


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dyn085

dyn085

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Thread Starter #7
Randy at Mountune has a specific set of parameters he wants logged. I found these on the other forum, and confirmed them with him. One thing not mentioned directly, but alluded to was qualify of gas. Specifically ask your tuner which brand of gas he recommends. In my case, he wanted me to use Arco and Propel. He also does not want more than one or two runs. Do not shift iOne thing not mentioned directly, but alluded to was qualify of gas. Specifically ask your tuner which brand of gas he recommends. In my case, he wanted me to use Arco and Propel. He also does not want more than one or two runs. Do not shift into 4th ntoat the end of your third gear run, before you stop datalogging, and I recommend having ESC off before a pull. I did my pulls a couple of blocks away from my home at 3:30 A.M in the morning on a flat, two lane road. going one way, then back the other way. Practice makes perfect. I could only have one gauge showing boost since Randy had a full set of data to log. Try to log before you actually log because you may need to reduce the number of gauges being displayed. Randy wanted the 3rd gear pull to start 10 seconds after hitting less than 2000 RPMs, and end at redline.

Get a copy of VDyno (Virtual dyno). Its free, but you will need to input your variables into a profile. The correct data is floating around the other site, and also, I believe on this site. Randy and I worked on my e40 tune. I also run a Cobb stage tune 91 octane. Once everything is finalized, I plan on getting a dynotune.
I definitely agree with the majority of your post, which is why I said to always defer to your specific tuner. While tuning processes are similar, there can/will be differences in parameters logged and the method that they would like to see them collected. This is just a general guideline to help familiarize people with the overall process that maybe have no idea where to start from the beginning.

I should also probably re-word the first point 6 because the reason for testing your gauge setup before even heading out to do the datalog is exactly what both you and ISO mentioned-you may not be able to collect the full list of parameters depending on what your gauge setup is.

Now I would like to touch on what I bolded in your statement. It is definitely pertinent to ask your tuner for fuel recommendations and wise to give it a shot, but unless your tuner lives in your neighborhood and utilizes stations that are within your level of convenience there is absolutely no possible way that he can tell you exactly what the best fuel is, short of having you send in multiple logs from every single station. I've seen lots of posts from both members and tuners that state that 'x' brand is the best or that 'x' brand is the worst and it's simply not true. The absolute only way someone is going to know what fuel is the best for them is to do their own logging and testing of the stations within their local area and convenience.

Even the advice that I've posted is exactly that-advice. Some people will find that they need to make changes or do something different due to their environment, and that's ok. There is no one 'perfect' pro tuner because if there was then we would all be using him. Always use your head when making your decisions. That's the main driving-factor behind the posts that I've been making recently-you can't make informed decisions simply because someone else that's nowhere near you said to do 'x'. If I can help people learn how to collect accurate data, they can make their own informed decisions based off of the data that they collect.
 


westcoaST

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#10
I agree with you on the location of the tuner and tunee (Is that a word???). In my case Randy and I live and work in the same area. I used to use Shell, but he convinced me to run Arco in OC/Riverside area. Funny thing is my Mustang tuner swears by Shell. I pick up my Mustang tomorrow. It will be interesting to pick his brain on the top tier gas issue. His place is in San Bernardino, CA. Spankintime Performance.
 


rexdriver85

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#11
No datalogging for me yet, but I have run Shell 93 exclusively since I've bought the car and from the same station every time.

Just got my AP 2 days ago and after the install OAL went straight to -1. I almost don't want to fill up anywhere else now that I can see it does indeed seem to be good fuel.

I hope this isn't a hijack, but I've been seeing all positive corrections on the cylinders up to almost +5 so far.

This is healthy correct?
 


Kip2MyLou

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#12
That's all I ran too. And I need to learn these data logging terms. No idea what corrections are and what they should or shouldn't be. Ha.
 


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#13
Negative ignition correction would mean the ECU is seeing knock, and cutting timing to try and fix it. Positive numbers mean that the ECU isn't seeing knock, and is able to advance timing more.
 


Kip2MyLou

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Got it; negative bad, positive good.

Now that I have that down, time to learn some more. Ha. I've had the AP for over a year now and haven't really done anything with it except when changing to new maps. I don't keep it in my car though so that's probably why. I need to utilize more especially if I can get randy to make me one of his kick ass e maps.
 


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dyn085

dyn085

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Thread Starter #15
No datalogging for me yet, but I have run Shell 93 exclusively since I've bought the car and from the same station every time.

Just got my AP 2 days ago and after the install OAL went straight to -1. I almost don't want to fill up anywhere else now that I can see it does indeed seem to be good fuel.

I hope this isn't a hijack, but I've been seeing all positive corrections on the cylinders up to almost +5 so far.

This is healthy correct?
I've never seen OAR move off of -1, nor have I heard of anyone that has. Once it's there it's there until you retune. Where you will see your differences lies in the ignition corrections.

As for ignition corrections, I would use the term 'safer' as opposed to 'healthy', though that's just my opinion. In a perfect world, a 'healthy' and properly tuned engine would not see ignition corrections, positive or negative. That would signify a perfect tune for the mechanical setup of the vehicle. Realistically speaking, that will most likely ever happen unless you're tuning your own car and making adjustments on every possible table.

Given the fact that you're going to see corrections, you would ideally want to see only positive corrections. Positive corrections show that there is room to grow in your tune. Negative corrections, otoh, show that your tune is excessively aggressive. Some people believe that negative corrections are fine because the system is designed accordingly, but just because it can doesn't mean that that is optimal. Negative corrections, overly simplified, are a sign of an aggressive tune for the mechanical setup or poor fuel quality for the tune.

That's all I ran too. And I need to learn these data logging terms. No idea what corrections are and what they should or shouldn't be. Ha.
Corrections are additions or subtractions to the base timing table. Being at the threshold of knock is optimal, and the system will strive to be there as closely as possible. If the knock sensors are not picking up any knock, it will add timing to the base table until it either maxes out or achieves knock. On the other hand, if the sensors are picking up knock it will remove timing from the base table, which will show up in negative numbers.

Edit: Basically what Bryan said, plus a couple hundred words or so.
 


Kip2MyLou

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#16
I've never seen OAR move off of -1, nor have I heard of anyone that has. Once it's there it's there until you retune. Where you will see your differences lies in the ignition corrections.

As for ignition corrections, I would use the term 'safer' as opposed to 'healthy', though that's just my opinion. In a perfect world, a 'healthy' and properly tuned engine would not see ignition corrections, positive or negative. That would signify a perfect tune for the mechanical setup of the vehicle. Realistically speaking, that will most likely ever happen unless you're tuning your own car and making adjustments on every possible table.

Given the fact that you're going to see corrections, you would ideally want to see only positive corrections. Positive corrections show that there is room to grow in your tune. Negative corrections, otoh, show that your tune is excessively aggressive. Some people believe that negative corrections are fine because the system is designed accordingly, but just because it can doesn't mean that that is optimal. Negative corrections, overly simplified, are a sign of an aggressive tune for the mechanical setup or poor fuel quality for the tune.



Corrections are additions or subtractions to the base timing table. Being at the threshold of knock is optimal, and the system will strive to be there as closely as possible. If the knock sensors are not picking up any knock, it will add timing to the base table until it either maxes out or achieves knock. On the other hand, if the sensors are picking up knock it will remove timing from the base table, which will show up in negative numbers.

Edit: Basically what Bryan said, plus a couple hundred words or so.
Sounds good. Not to hijack the thread but what's the best gages to run and/or things to look for with your accessport?
 


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dyn085

dyn085

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Thread Starter #17
Got it; negative bad, positive good.

Now that I have that down, time to learn some more. Ha. I've had the AP for over a year now and haven't really done anything with it except when changing to new maps. I don't keep it in my car though so that's probably why. I need to utilize more especially if I can get randy to make me one of his kick ass e maps.
While I can understand why many people may not keep it in their car, it is a valuable and powerful tool for those that do. It can help you measure and quantify performance, assist in locating/solving problems, inform you if you have a bad tank of fuel, warn you of impending issues...Even if you only put it in and datalog a couple of times a month, it can give you a much deeper knowledge of your engine.


Sounds good. Not to hijack the thread but what's the best gages to run and/or things to look for with your accessport?
That's mostly dependent on the person or situation. The main gauge set that I personally use for daily-driving is the 4-gauge with AFR, Boost, Ign Correction on cylinder 1, and oil temperature. I have other gauges set up for other situational uses, and occasionally will be testing something specific and change a set of gauges according to the data I want to see and am most likely logging.
 


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Sounds good. Not to hijack the thread but what's the best gages to run and/or things to look for with your accessport?
I haven't set up my gauges in mine yet, because I just got it a few hours ago, and only gave it a quick spin. BUT on my WRX I ran AFR, ignition corrections for each cylinder, and injector pulse width (I was running 770cc injectors when I couldve benefitted 1,000cc, so I liked to monitor them). You may want to run boost if you don't have a mechanical gauge like I did. Other good things are oil temps and charge temps. There's tons of useful monitors, just have to decide what you may want to keep an eye on according to your car/climate/conditions.
 


Kip2MyLou

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#19
While I can understand why many people may not keep it in their car, it is a valuable and powerful tool for those that do. It can help you measure and quantify performance, assist in locating/solving problems, inform you if you have a bad tank of fuel, warn you of impending issues...Even if you only put it in and datalog a couple of times a month, it can give you a much deeper knowledge of your engine.



That's mostly dependent on the person or situation. The main gauge set that I personally use for daily-driving is the 4-gauge with AFR, Boost, Ign Correction on cylinder 1, and oil temperature. I have other gauges set up for other situational uses, and occasionally will be testing something specific and change a set of gauges according to the data I want to see and am most likely logging.
Reason why you only do cylinder 1?
 


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dyn085

dyn085

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Thread Starter #20
While I was going through my datalogging, cylinder one showed to be statistically the weakest. Not necessarily by a notable difference, but enough for it to be the best overall picture of the remaining cylinders.
 


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