Vag-Com Data Logging FAQ...(first revision)....

[bhvrdr]

Hi all,
Just starting a write up on vag com data logging. I have a lot more channels to cover but would appreciate you all looking this over and posting suggestions and corrections as necessary. Most of the info comes from my memory and experience so I would very much appreciate corrections and additions. Hopefully this will be helpful to people. cheers! Mike

Note: In order to have a log that will be valid, you will need to see at least a 3rd gear wide open throttle run from about 2500rpm until redline. Any lifting of the throttle during the run will result in inaccurate A/F numbers for the purpose of our evaluation.

Channel 1: Lambda Correction

This is a fuel correction table used by the computer when it senses the car richening and leaning. The numbers will be displayed as a percentage starting from 0% indicating NO fuel correction is needed. This means the car is doing what it should be. No fuel is having to be added or removed to maintain harmony. The computer can correct for these rich and lean conditions up to 25% or so. Note that seeing numbers higher than 0 does not necessarily mean your car is running dangerously rich or lean just because of a little correction. Positive numbers displayed indicate fuel is having to be added to compensate for lean conditions. Negative numbers indicate fuel is having to be removed to compensate for a richer condition. The lower the numbers the better. Numbers upwards of 20 indicate some real problems that bear much closer attention. Remember that lean is your ultimate enemy.

Channel 2: g/s MAF Sensor

This channel measures the grams per second or airflow taken into account by the MAF sensor. Input I have collected from tuners suggest that this is not a direct measure and depends on other sensors, so programming may be able to affect the g/s independent of changes to actual airflow. Nevertheless, while this may not be a reading that can completely state the airflow your car is taking in, it can provide a good estimate. This is a great log to look at if you suspect a common failure, the dying MAF sensor. On a chipped car one would expect MAF numbers to increase linearly as the car approaches redline. Your highest numbers will be seen at or near redline and are likely to be in the neighborhood of 160-180 g/s. Low numbers at redline such as 120 g/s are a good indicator your MAF is on the way out. Codes may not be thrown at this point. Terribly low or NO readings means she is dead.

Channel 20: Timing Retard for Each Cylinder

This channel is very straight forward. You should see a field of 0s everywhere. The number 0 in each of the cylinder boxes indicates NO timing retard is taking place. This means no timing is having to be removed by the computer as it senses knock or leanness. Now, what if you see some random numbers like "1.5� and "3� every once in awhile? This should be fine. If you were a tweaker, ideally you would want to find that point where you are able to use the most timing without triggering problems. Since most people do not mess with timing adjustments, we want to see as close to zero as possible though. Timing retard of greater than "6� would have me worried and I would want some further investigation and adjustments made.

Examples:

CAR RUNNING TOO MUCH TIMING

RPM CYL 1 CYL 2 CYL 3 CYL 4
2500 0 0 0 0
2750 0 0 0 0
3000 0 0 0 0
3250 3 0 1.5 4
3500 3 3 4 4
3750 4 6 6 6
4000 3 0 3 4
4250 6 6 6 6
4500 6 6 6 6
4750 6 4 6 4
5000 8 6 8 4
5250 0 4 6 8
5500 6 6 6 6
5750 8 4 6 6
6000 6 6 6 4
6250 8 8 8 8
6500 8 6 6 6
6750 6 6 6 6


CAR RUNNING AGGRESSIVE TIMING (performance tuned)

RPM CYL 1 CYL 2 CYL 3 CYL 4 Retard
2500 0 0 0 0
2750 0 0 0 0
3000 0 0 0 0
3250 0 0 0 0
3500 0 1.5 0 0
3750 3 0 0 1.5
4000 0 0 3 0
4250 1.5 1.5 3 3
4500 3 3 3 3
4750 1.5 3 1.5 1.5
5000 3 3 6 3
5250 0 1.5 3 0
5500 3 3 1.5 1.5
5750 3 4 3 1.5
6000 1.5 3 1.5 4
6250 3 3 3 3
6500 4 3 3 3
6750 1.5 3 1.5 3

CAR RUNNING VERY SAFE TIMING

RPM CYL 1 CYL 2 CYL 3 Cyl 4 Retard
2500 0 0 0 0
2750 0 0 0 0
3000 0 0 0 0
3250 0 0 0 0
3500 0 0 0 0
3750 0 0 0 1.5
4000 0 0 0 0
4250 0 0 0 0
4500 0 0 0 0
4750 1.5 0 0 0
5000 0 0 0 0
5250 0 1.5 0 0
5500 0 0 0 0
5750 0 0 0 0
6000 0 0 0 0
6250 0 0 0 0
6500 0 0 0 0
6750 0 0 0 0


Channel 31: Lambda Reading or A/F Ratio

This value is particularly important to be viewed and interpreted only when the car is under full throttle input as lifting up on the throttle will result in funky numbers. Take your log in third gear (or higher if your local authorities will allow) from 2500rpm or so until redline. The values you will see are: "1� = 14:1 ratio, ".85� = 12:1 ratio, ".75� = 10:1 ratio. A car that runs 14:1 (lambda value of about .95) all the way up to redline on increased boost is running a bit lean. Conversely, a car that is running 11:1 (lambda value of about .80) from idle to redline is running a bit rich. Remember that lean is your ultimate enemy. Running too lean for too long will spell disaster for the motor. It is ok for making power, but it is not ok for protecting the turbo and motor from failure. Ideally you would like to see the A/F pass linearly from the factory 14.7:1 at idle towards 13:1 in the mid rpms (3500rpm or so) to at least 12:1 at redline. This would show a car that is getting good fuel mileage under easy driving, but richens up nicely as you wind it out under full throttle to redline. This would make you feel at ease driving the car under high load conditions at high speeds (freeway cruising at 120mph) or using the car for frequent track days.

This would be nice:

RPM Lambda
2500 .99
2750 .95
3000 .95
3250 .95
3500 .90
3750 .90
4000 .90
4250 .85
4500 .85
4750 .85
5000 .85
5250 .85
5500 .85
5750 .85
6000 .80
6250 .80
6500 .80
6750 .80

Channel 34: EGT (Exhaust Gas Temperatures)

Pretty straight forward here and a great channel to use to give you the heads up that other things are going wrong. This monitors the exhaust gas temperatures of the car. You want to see what the limits are here and it will take some beating on the car to find it. When the car is still warming up, your readings may not accurately reflect just how high these temps can get. Take your car out for some spirited full boost runs, then start logging in the normal 3rd gear WOT manner. Exhaust gas temperatures at 900 degrees Celsius and below are common for our engines when heavily boosted. This sensor appears to be only accurate up to 950 degrees Celsius or so. If you see readings creeping up this high, you have a great indicator that something is not right on your car and your engine is not happy with you. Running too high of temps for too long will spell disaster.

Channel 115: Requested Boost and Actual Boost

This is a very helpful channel for diagnosing boost leaks, trying to figure out why your car went into limp mode, and seeing if the software or hardware (electronic or manual boost controllers) are doing what they should be. This channel displays the boost requested by the computer (requested boost) in the first column and the boost actually made by the turbo (actual boost) in the second column. The readings you will see here can be misleading. First, you should know that the numbers you will see are not yet corrected for atmospheric pressure (about 1040mbar at sea level). The atmospheric pressure seen at the boost sensor is tough to estimate with complete precision, but I have found that subtracting 1000mbar from the numbers gets you close enough to actual boost unless you are living at 20,000 feet above sea level. The next thing you have probably noticed about these numbers are that they are displayed in mbar instead of psi like we are all used to. Well, this won’t be a problem thanks to the metric system. 1000mbar = 1 bar and 1 bar = 14.5psi. There you have it.

So, can we all figure out what boost level in psi this car is requesting and making at 3000rpm?

RPM Requested Boost Actual Boost
2500……2100…..1800
2750……2200……1950
3000……2200……2250
3250……2200……2200
3500……2200……2100

The correct answer is…

The computer is requesting 1.2 bar of boost at 3000rpm. This can also be expressed as 17.4psi.

The turbo is boosting 1.25 bar of boost at 3000rpm. This can also be expressed as 18.1psi.

So why are the above numbers important to us other than acting as a boost guage to entertain us? Well, as you can imagine, if you had a boost leak you would have a car that is requesting the correct boost but you would see very little in the actual boost column. In the case that you had just installed your new little boost controller or N75 valve you could do some logging to find that your actual boost was far exceeding your computer’s requested boost numbers causing your car to go into limp mode due to it’s sensing and “overboost� condition. For those of us who dare to run a turbo that was not designed specifically for the software they are using, this is a great way to see why it is not working out for you. For example, the boost maps on a K03 will show the ECU requesting max boost at around 3000rpms (this is a small turbo that makes its boost low in the rpm range). Now if you were to throw on a Garrett gt28r or T28 turbo or even larger you would see that the computer will still request the max boost at 3000rpm, but the turbo is not capable of making it’s max boost until closer to 3800rpm leaving you with an “underboost� condition.

NOTE: The sensor will only measure up to 2540mbar including atmospheric pressure. This means that if you are running more than 1.5bar or 21.75psi of boost this sensor will not measure beyond it. Both values will show maxed out at 2540mbar.

[1/4 scale]

really great info mike, thanks!

[bhvrdr]

no problemo. it helps me organize everyting as well. i just added another channel. any input guys? cheers! Mike

[zemun2]

Here's few to add:

Block 026 Knock control, knock sensor voltage (amplifier factor included)

Not to exceed 20 V

Block 120 ASR/FDR

Engine moment

nm / 1.35 = ft/lb

Blocks 015 and 016 Misfire recognition

Block 002
Mean injection time [ms]
Injector Duty Cycle

[1/4 scale]

Mike you need to make this a "Tech" article!

How about adding rpm vs. intake temperatures to monitor intercooler effectiveness? (Block 04?)

Thanks again.

[bhvrdr]

Originally posted by zemun2
Here's few to add:

Block 026 Knock control, knock sensor voltage (amplifier factor included)

Not to exceed 20 V

Block 120 ASR/FDR

Engine moment

nm / 1.35 = ft/lb

Blocks 015 and 016 Misfire recognition

Block 002
Mean injection time [ms]
Injector Duty Cycle

Thanks Dejan. I'll get to working on the block 26. On, block 002, I havent seen anyone who can find our mean injector time be useful. There are crappy equations on the net that supposedly convert it to the injector duty cycle but they do not apply to our cars. Similarly to how you can use those RC flow calculators to check injectors and they are way the hell off for our cars. Do you have any insight into this? I'll need your help on that one. Thanks. cheers! mike

[zemun2]

Originally posted by bhvrdr
Thanks Dejan. I'll get to working on the block 26. On, block 002, I havent seen anyone who can find our mean injector time be useful. There are crappy equations on the net that supposedly convert it to the injector duty cycle but they do not apply to our cars. Similarly to how you can use those RC flow calculators to check injectors and they are way the hell off for our cars. Do you have any insight into this? I'll need your help on that one. Thanks. cheers! mike

I'm using the same crappy online calculators everyone else is using. It's not perfect but it can be used as a guideline

[marklar182]

I was just searching for this stuff elsewhere today. Great info!

This isnt logging info but I thought it was good info to have;
http://audizine.com/forum/showthread...threadid=33367

[giago]

Hey mike great stuff.

Yesterday I got some weird readings on the 031, it was near 90-99 at low revs and when i was accelerating about 5000rpm+ it was reading 1.99 I got worried, that would be extremely rich right? could the reading be wrong?
I'll do new logs tomorrow and post them.

If you remember I'm making very little boost. like 8psi max, and they start going up until 4000. does it has something to do whith the a/f?

[bhvrdr]

Originally posted by giago
Hey mike great stuff.

Yesterday I got some weird readings on the 031, it was near 90-99 at low revs and when i was accelerating about 5000rpm+ it was reading 1.99 I got worried, that would be extremely rich right? could the reading be wrong?
I'll do new logs tomorrow and post them.

If you remember I'm making very little boost. like 8psi max, and they start going up until 4000. does it has something to do whith the a/f?

That would mean impossibley lean. What 1.99 looks like is that you lifted off the throttle or got ready to shift. cheers! mike

[Saturnine]

Thanks Mike!!

I really need to sit down with my vagcom and figure out how it works, and how i can apply that info into making my car run better..

[Vortec4800]

Originally posted by bhvrdr
NOTE: The sensor will only measure up to 2540mbar including atmospheric pressure. This means that if you are running more than 1.5bar or 21.75psi of boost this sensor will not measure beyond it. Both values will show maxed out at 2540mbar.

Will this cause problems for the computer and engine, thinking there is only 21.75 psi and trying to get the a/f ratio for this number, even though there is actually 23+ psi going in that the computer can not recognize?

[bhvrdr]

Originally posted by Vortec4800
Will this cause problems for the computer and engine, thinking there is only 21.75 psi and trying to get the a/f ratio for this number, even though there is actually 23+ psi going in that the computer can not recognize?

Excellent question. The answer seems to be not at all. The maps themselves can be written for higher boost and although you can't read it on the vag-com as boost, you can see that the a/f keeps right up with whatever is programmed. The chip I have is labeled a 1.35 bar chip which means it holds 1.35bar. Of course it spikes a bit higher than that (about 23psi spikes). At times I run an N75J or K valve and see 26psi and 29psi spikes respectively. The fuel keeps up perfectly. Some people even see it as a tiny bit rich. cheers! Mike

[A_loha_4]

This is great info. Thanks.
I have one to add:
Block 14 shows misfires in total - for all cylinders
Block 15 (as mentioned by zemun2) shows misfires by cylinder for cylinders 1-3
Block 16 (as mentioned by zemun2) shows misfires by cylinder for cylinder 4

[teutonic_blur]

I've read (but I haven't verified it myself) that block 32,2 indicates ECU O2 adaptation values from -10% to +10%. Negative values indicate engine is running rich, positive means lean.

BTW excellent idea Mike.

[bhvrdr]

Originally posted by teutonic_blur
I've read (but I haven't verified it myself) that block 32,2 indicates ECU O2 adaptation values from -10% to +10%. Negative values indicate engine is running rich, positive means lean.

BTW excellent idea Mike.

Good call. A lot of these values are repeated in several channels. You can find it first in channel 1. For some reason I seem to get a quicker reaction out of channel 1 so I tend to use that one for fuel adaptation. It will correct upwards of 25%, but hopefully none of us are seeing that much. Thanks for wathching out. Keep up the input everyone. cheers! mike

[400HPA4]

Mike can you add how Joe Hoppen changes the timing on the MTM setup with the VAG-COM?

[bhvrdr]

Originally posted by 400HPA4
Mike can you add how Joe Hoppen changes the timing on the MTM setup with the VAG-COM?

Good call Greg. I will do that. I'll put in a call this week. Thanks. cheers! mike

[400HPA4]

This is awesome...not to bust anyones balls...but maybe after all of this info is gathered...we can turn this into a "how to" for the tecj forum with screen shot and instructions.

I wouls be happy to take some, but I am stuck over here.

[GreyGhost]

great work Mike, thanks again for your help. TJM says my numbers look fine to them and think that I'm triggering the knock sensor from somewhere else...ie exhaust (but it's stock), bad knock sensor. I am, however, still a little concerned about the channel 20, which has shown a timing retard of max of 6 in third gear. We'll see how things go, I'm hoping to bring the car up to TJM in the next couple o weeks. thanks again for your help. Great info!!

[1stA4]

Moderators, an we make this an ongoing tech so people that are trying to use their vags can easily find this thread. Thanks!

[giago]

My last log any thiughts about it. It was in third gear, I had to brake at 5800.
hopefully tomorrow I'll make new & better ones.

What else should I log.

[bhvrdr]

Everything looks safe. A couple of points of interest. Looks like your turbo could be making a bit more boost to meet requested and it looks like your car is hitting a 9:1 a/f ratio and heading richer by redline. I'd rather be rich than lean, but perhaps a tiny bit of tweaking could be done. Main point, is that it looks safe. Log channel 20 (timing retard), and channel 2 (maf sensor) and channel 34 (egt). Congrats sir. cheers! mike

[giago]

On the channel 20 I'm getting cero almost all times.
I don't run a MAF, and I will log 034.
I'm thinking of getting a MBC, but in sometime I have planned to go Standalone. whith EFI032. Should I get it in the mean time?

So I can push the car, No prob??

Thanx.

[bhvrdr]

Originally posted by giago
On the channel 20 I'm getting cero almost all times.
I don't run a MAF, and I will log 034.
I'm thinking of getting a MBC, but in sometime I have planned to go Standalone. whith EFI032. Should I get it in the mean time?

So I can push the car, No prob??

Thanx.

Grab your EGT temps which I would already have to guess are within normal limits and it looks like you have a pretty clean bill of health. When collecting the EGT please make sure the car is fully warmed up and make sure you trash on it as hard as you can to redline to get the absolute highest temps. I'm going to put out a guess and bet you see a top of 895-905 if you try hard enough. That would be nothing to fear. cheers! Mike

[German Driver]

Vote to sticky!

[Saturnine]

And you can do this all with the shareware version of Vag-com?

[400HPA4]

PM the right person and he can hook you up

[bhvrdr]

Originally posted by Saturnine
And you can do this all with the shareware version of Vag-com?

I believe the shareware limits you up to about channel 20 or so. After that you need to register. If you have the shareware, you can use channel 1 to get a rough idea of what your fuel is doing instead of channel 31. It's not a direct measure but I guess it's better than nothing. I believe you can get the full registered vag-com for right around $180 not though from www.obdtool.com or just a bit more from www.ross-tech.com This really should be the first performance "mod" before a chip. cheers! Mike

[400HPA4]

I concur

[giago]

GREAT MOD

[bhvrdr]

Just figured i'd bump this if anyone needs it. I've had a few emails. cheers! Mike

[madrussian]

i dunno how i missed this thread early on, but this is exactly what ive been looking for...

[martini]

bump cuz i need this info

[QuattroRocket]

I am trying to sort out some issues with my car and am working with a tuner 6 hours away so these are the blocks he has asked me to log and send to him:
115 - boost
119 ?
003 ?
026 ?
004 ?

[Jet Jockey]

Originally posted by QuattroRocket
I am trying to sort out some issues with my car and am working with a tuner 6 hours away so these are the blocks he has asked me to log and send to him:
115 - boost
119 ?
003 ?
026 ?
004 ?

003 = System with mass airflow sensor. You get the RPM read out, the Air mass in G/S, the Throttle valve angle in %, the Ignition angle (actual).

004 = General. You get RPM, the Voltage, the cooling temperature in degrees C, the Intake air temperature in degrees C.

026 = Knock control, knock sensor voltage (amplifier factor included). You get cylinders 1-2-3-4 voltage.

119 = Boost pressure control. You get RPM, the Actual adaption value boost pressure control valve (%), the duty cycle boost pressure conntrol valve (%), the Boost pressure before throttle valve (mbar).

[Renga]

So if I want to check my Dahlbeck stage 4 setup, witch channels do I have to log?
I have the reged version of RossTech, I’m a total beginner in this!

[teutonic_blur]

Originally posted by Renga
So if I want to check my Dahlbeck stage 4 setup, witch channels do I have to log?
I have the reged version of RossTech, I’m a total beginner in this!

Blocks 1, 20 and 115 are good places to start. Refer to Mike's (bhvrdr) post at the top of this thread for info on what to look for.

[Renga]

All in 3rd gear! Commnets?

[IMG][/IMG]

[bhvrdr]

Everything looks real nice. A+. A/F is nice and safe and timing is not overly aggressive but right at the limit of retard. Nice setup. cheers! Mike