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boo-key 10-14-2013 07:53 AM

The Official datalog review thread
549 Attachment(s)
Hey guys, thought I would make a little thread for datalog reviews since from time to time we have members who need it. I know there's only a hand full of you experienced enough to read them and know what your looking at so, If you don't mind helping out your fellow members please do! If your too busy or just don't want to the that's fine as well. To the ones who want to help, just let us know your preferred gear and parameters to log. I know usually it's WOT in 3rd gear 2.5k rpm-redline. If your profile is not up to date you will also need to include info about your modifications. As far as posting logs, Google Docs has a service where you can upload your spreadsheet files and you can post a link for others to view. This is a free service. [url=]Redirecting...[/url] . Someone may know some other or easier ways they can share as well. This thread can also be a good way for some of us who don't know a lot about it like myself, to gain knowledge and insight into tuning. If anyone has anything to add, please feel free. Thanks in advance to our tuning gurus nice enough to participate.

Here are some parameter definitions to help out.


Seconds (sec)[AP] or Time(ms)[RR]

This is the time elapsed during the datalog. RR datalogger lists this time in milliseconds.

RPM (RPM) [AP] or Engine Speed (RPM) [RR]

This is your engine speed. Measured in RPM.

Calculated Load (load) [AP] or Engine Load (1 byte) (g/rev) [RR]

This is the load on the engine. It is calculated by using data from the MAF sensor to calculate how much air is entering the engine per revolution. Engine load is used throughout the ECU as a variable to control the ECU's tables regarding everything from ignition timing and AVCS timing to how much fuel is used.

Dyn. Adv. Mult. (DAM) or IAM [RR]

This is used as part of Subaru's knock control strategy. The Subaru ECU pulls timing to reduce knock and in extreme cases can richen the fuel mixture and disable boost control leaving you at wastegate boost. This value is multiplied to the timing advance table and added to the Base timing table to create the maximum timing advance. If the value is 1 full timing advance is being used. If the value is less than 1 only that fraction of the timing advance table is being used.

ex. If the DAM equals .5 and the timing advance table calls for 5 degrees advance. .5*5 = 2.5 degrees will be added to the base timing.

What you need to know. The DAM is set in a stock ecu to .5 after ecu reset. The tuner may modify this value to start at any value they want. Generally as you drive around this value will increase to 1. You will need to be at engine loads that apply timing advance to raise this multiplier as well as other factors. If your car does not raise this DAM or reduces it. It is because of feedback from the knock sensor. This is an indication that either knock is occurring or false knock is being picked up through the knock sensor. It is a safety precaution when bad gas or low octane gas is used.

If the value drops below .35 the alternative open loop enrichment table is used. This is a much richer table then the normal open loop enrichment table.

If the value drops below .2 the ECU disables Boost control. This will leave you car running at wastegate boost and you will always have 0% Wastegate Duty Cycle. It will not be turned back on till the DAM increases to above .65.

The value you are looking for is a DAM of 1 (32 bit ecu) or 16 (16bit ecu)

Ignition Adv. (deg)[AP] or Ignition Total Timing[RR]

This the total amount of ignition advance currently being used by the engine. It is measured at cylinder 1 so 'per cylinder' ignition changes will only be seen if they are applied to cylinder 1

Learned Ign. (deg)[AP] or Ignition Timing Advance (degrees)[RR]

This is the amount of timing that is added to ignition base timing to create the total timing used.
It is calculated by
DAM* Timing advance table - Knock Correction - Knock Learning
Or To RR users
IAM*Timing advance table ‚ Feedback Knock Correction ‚ Fine Learning Knock Correction.

Knock Correction (deg)[AP] or Feedback Knock Correction(degrees)[RR]

This is the total timing being pulled when the ECU picks up a knock event. This is an indication that the ecu has detected knock from the knock sensor. It will continue to pull timing for a period of time after knock has occurred. If the ECU sees another knock event additional timing will be pulled. Although this can be changed by the tuner generally -1.4 is used for each knock event.

What you need to know. It is important to not see Knock Correction at high engine loads from about 1.8 up. It would be ideal to not have any knock events at all even at low loads. However the knock sensor may hear other noises that it cannot distinguish from knock. Sometimes rattling heat shields, clutch and transmission noises or even loose bolts or nuts sitting on top of the engine can set off the knock sensor.

Knock Learning (deg)[AP] or Fine Learning Knock Correction (degrees)[RR]

This is the timing being pulled when the ECU has learned to pull timing to protect from knock. Over time the ECU will slowly advance timing back as long as no new knock is occurring. Timing will be pulled in increments of -1.4. The knock sensor is used by the ECU to determine if knock is occurring.

Knock Sum

"Knock sum will increment at idle and low RPM where the ECU is extremely poor at distinguishing actual knock from other engine noises. This is why the ECU does not respond to "knock" events in this area. The knock sum value itself is meaningless because of this. You have to look at when it increments and ignore changes at idle and low RPM/load. Cylinder #4 will see more counts even on a stock engine, likely due to the relationship between the placement of the knock sensor on the block and cylinder #4.

Bill" (from Bill at Cobb)

Throttle Position (%)[AP] or Throttle Opening Angle(%)[RR]

This displays the current throttle position. Because Subaru doesn't use an idle control valve on drive by wire cars. With your foot off the gas it will still leave the throttle open about 2 degrees to keep the car idling.

Boost (PSI)[AP] or Manifold Relative Pressure(corrected)(PSI)[RR]

This displays the current boost pressure relative to current atmospheric pressure.
You would want this value to not go past the Boost pressure described by the maps notes.

Wastegate Duty (%)[AP] or Primary Wastegate Duty Cycle(%)

This is the current wastegate duty used by the ECU to achieve a target boost level. At 0% wastegate duty cycle the car will operate at wastegate boost.(7-9 PSI on WRX's) Wastegate duty cycle controls the amount of air that will pass through the boost control solenoid to the wastegate actuator. The wastegate actuator will open at a set PSI (7-9PSI on WRX's). The boost control solenoid limits the amount of boost that will be seen by the wastegate actuator. The higher the wastegate duty the less pressure is seen by the wastegate actuator. Higher wastegate duty's will result in higher pressure levels.

Turbo Dynamics (PSI)[AP] or Turbo Dynamics Integral (4-byte)*(%) & Turbo Dynamics Proportional (4-byte)*(%)[RR]

This displays the change in wastegate duty by the ECU to achieve a target boost level.

Air/Fuel Ratio (AFR)[AP] or A/F Sensor #1(AFR)[RR]

This displays the current AFR as measured from the front wideband oxygen sensor. It is normal to see readings around 14.7 AFR during idle and cruise. The AFR's will also climb to the 20's on deceleration because the injectors are shut off. The sensor is only accurate for determining AFR's during light throttle, cruise and idling. Because of it's location on the exhaust manifold, the exhaust gases become compressed as the turbo is spooled. The compressed exhaust gases cause the the sensor to read richer then actual AFR. The ECU does limit output of the oxygen sensor. Generally it will read down to the low 11's.

You need a wideband placed post turbo to measure actual AFR during WOT. If the stock oxygen sensor is reading AFR's above this lower limit at high boost levels it most likely running dangerously lean.

Inj. Pulse Width (ms)[AP] or Fuel Injector #1 Pulse Width(ms)[RR]

This is the current injector pulse width measured in milliseconds.

Inj. Duty Cycle (%)[AP] or Injector Duty Cycle(%)[RR]

This is the percentage of time during 2 revolutions of the engine that the fuel injector is open. It is calculated using engine speed and Injector Pulse Width. There has been lots of debate in the tuning community as to the accuracy of this value. Many tuners have seen fuel enrichment above 100% which is theoretically impossible. This has believed some to assume that the injector pulsewidth may not be accurately being converted from the raw ECU data.

What you need to know. If you are getting close to 100% or above in injector duty cycle your injectors are being about maxed out. This may be caused from the car running too rich or you are approaching the limits of your current fuel system.

Mass Airflow (g/s)[AP&RR]

This is the current amount of airflow going past the MAF sensor. It is pretty close to a measure of actual Wheel Horsepower. These numbers will vary with different stages and environmental conditions. If you have a boost leak it is likely that these numbers will appear to be much higher than normal. If you have a pre-turbo intake leak these numbers may be lower than normal.

MAF Voltage (V)[AP] or Mass Airflow Sensor Voltage(V)[RR]

This is the current Mass Air Flow sensor voltage. The voltage from the MAF determines the Mass Airflow (g/sec) along with other factors.

boo-key 10-14-2013 07:58 AM

549 Attachment(s)
I'll start. I'm pretty sure mine looks alright but, never hurts to get a second opinion. 2006 wrx catless tbe, sri, ewg, ebcs,& tgv del. First is 3rd gear wot. second is a bit of normal driving. [url][/url]

dirtydeeds02 10-14-2013 03:33 PM

Well written post. Very informative

Nathan21 10-14-2013 04:04 PM

very nice post, bet this will get interesting

thekamikaze kid 10-14-2013 05:56 PM

the only problem with my log is that the dam is at 11 when it should be at 16, i have been working with cobb and they suggested it was a mechanical problem. i get lag going up hills or at early rpms. it started before i went to stage one and im still getting this issue.


boo-key 10-15-2013 03:09 AM

549 Attachment(s)
[quote=thekamikaze kid;374313]the only problem with my log is that the dam is at 11 when it should be at 16, i have been working with cobb and they suggested it was a mechanical problem. [/quote]

I was driving today and noticed on my ap that the DAM was at .188 for my entire drive. Next time I got in it was back to normal at 1 and has been ever since. I took a log at idle when this happened. Weird :confused:

thekamikaze kid 10-15-2013 08:02 PM

yah im gonna try one more time to monitor the dam and if it does not go up ill take it to a mechanic. since i flashed it it has been pretty solid at an 11. its been about 50 miles since ive flashed it and i have been taking it easy. cobb said it could take 50-500 miles to get used to the tune. hopefully it goes up at least a little tomorrow.

pzr2874 10-16-2013 08:46 AM

^you need a real log to post.

And a real tune.

Ok, I'm done.

Nathan21 10-16-2013 01:06 PM

now that was a little mean Paul

pzr2874 10-16-2013 03:47 PM

You can't post half a log.... unless you want half the answers. Not trying to be mean at all. Just stating the facts.

thekamikaze kid 10-16-2013 04:09 PM

like i said it is hard to get a good datalog around where i am cause its all mountain. still though, the fact is that the dam is too low and it either needs to learn the tune or i have a problem under the hood. the log i have posted is a 3rd gear wot pull to about 4800 rpm, its the best i could do with the road i had, eventually i will get a better log when i find some decent road. oh and btw i can tell u it is a REAL cobb stage 1 93 oct tune i assure u. i suspect i have a mechanical problem due to the lag and the dam not "learning" fast enough. if u cant help dont post.

boo-key 10-16-2013 05:16 PM

549 Attachment(s)
[quote=pzr2874;375169]^you need a real log to post. [/quote]

Would a log at idle help to begin diagnosing his problem since the dam is low and that happens in vacuum as well as boost? Kinda like a starting point for diagnosis.

pzr2874 10-16-2013 05:54 PM

[quote=thekamikaze kid;375313]like i said it is hard to get a good datalog around where i am cause its all mountain. still though, the fact is that the dam is too low and it either needs to learn the tune or i have a problem under the hood. the log i have posted is a 3rd gear wot pull to about 4800 rpm, its the best i could do with the road i had, eventually i will get a better log when i find some decent road. oh and btw i can tell u it is a REAL cobb stage 1 93 oct tune i assure u. i suspect i have a mechanical problem due to the lag and the dam not "learning" fast enough. if u cant help dont post.[/quote]

Touche young padawan..... I can in fact help you. But throwing that log up on several threads will not change anything.

I helped in the last thread... and you continue to throw that shit up.

Buck up and get a real log or jump on a dyno.

As far as logging at idle, I haven't a clue. A 3rd gear log is short as it is. Need to see the AFR's during the entire WOT 3rd gear pull from 2800ish - close to redline.

thekamikaze kid 10-16-2013 06:38 PM

ill try to get one up next week.

thekamikaze kid 10-20-2013 08:39 PM

im taking it in on tuesday, after talking with my mechanic i believe thaty it is a wastegate problem and that is the reason the ecu isnt learning the dam. ill post back with the results. i think the log is long enough for at least that diagnosis.

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