How To: VCDS Performance Logging

[jran76]

Several people have asked about logging their vehicle, so I put together a “how to” on logging with the Ross-Tech VCDS software and cable (VAGCOM). Logging is critical to understanding how your car is performing, and even more so if you are tuned. There are several parameters that can be logged that will give a good indication as to how your car is running, and if there are any problems. This “how to” guide will cover how to perform basic performance logging, and also how to interpret some of the results (covered in the next post).

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First, a few things:
*Every version of Ross-Tech software is slightly different. In terms of logging, the only real difference is the location number associated with each logging parameter. The name of the parameter will be similar from version to version, but the associated location number may be different. I am using version 12.12.1 in the screen captures below, but I have updated it with the parameters from version 15.7.1 (updated 10/8/2015). Regardless, your version may be slightly different. The software is updated often.
*One of the key things people like to log is requested and actual boost. In recent versions of the Ross-Tech software boost is not displayed as an absolute value. Some conversion and calculation is required. This is covered in the next post.
*While there are others ways to log a vehicle, this only covers using the full version of Ross-Tech software with their VCDS cable.
*Logging must be done with Windows software. That can be XP, Vista, Windows 7 or 8. Doesn’t really matter. An Apple/Mac that runs Windows will also work (Boot Camp, Parallels, etc.).

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Getting Started
Step 1: Plug the Ross-Tech VCDS cable into the OBDII port under the dash on the driver’s side.

Step 2: With the car on, launch the VCDS software.
*Note: The car can be in the ON position or running for steps 1-11.


Check for Fault Codes
Step 3: Before you start logging, ensure there are no fault codes. Press the “Auto-Scan” button on the VCDS main menu.

Step 4: Once in the Auto-Scan section, press the “Start” button to scan for codes. The scan will take a few minutes as it scans all modules. If there are faults, I would recommend saving the scan results (copy/paste, save, print), and then clear the faults with the “Clear all DTC’s” button. Once this is done, “Close” the Auto-Scan section, and return to the main menu.


Logging Setup
Step 5: Under “Select Control Module” press the “Select” button.


Step 6: Under the “Common” tab press the “01-Engine” module button.


Step 7: In the Engine Controller module, press the “Adv. Meas. Values” button to access the logging section.


Step 8: Select the “Ambient Air Pressure” value from the parameter list. Record the value displayed for future reference, and then uncheck the box. The ambient pressure value will be used later to calculate boost related values.


Step 9: Select the parameters you would like to log from the list.
*Notes:
-VCDS will let you select a maximum of 12 parameters, or 10 parameters if you use grouping (which is a must for good logs as we’ll cover below). So, concentrate on the parameters that are most important for this particular logging session. Fewer parameters logged will yield higher resolution logs.
-For general performance logging, I recommend the following parameters, but you can pick the appropriate parameter for your needs from the list:

For B8:
Group Number: Parameter Field (Units; details)
002: Accelerator position (in %)
009: Charge air pressure specified value (in hPa; specified boost+ambient air pressure)
018: Engine speed (in RPM)
089: Air mass (in kg/h; intake)
186: Ignition angle; actual (in degrees)
188: Intake air temperature (in degrees C)
190: Intake manifold pressure; absolute (in hPa; actual boost+ambient air pressure)
418: IGA_AD_KNK[0] (in degrees; knock detection/timing pulled on cylinder 1- Just pick 2 Cylinders to log)
419: IGA_AD_KNK[1] (in degrees; knock detection/timing pulled on cylinder 2- Just pick 2 Cylinders to log)
420: IGA_AD_KNK[2] (in degrees; knock detection/timing pulled on cylinder 3- Just pick 2 Cylinders to log)
421: IGA_AD_KNK[3] (in degrees; knock detection/timing pulled on cylinder 4- Just pick 2 Cylinders to log)
422: IGA_AD_KNK[4] (in degrees; knock detection/timing pulled on cylinder 5- Just pick 2 Cylinders to log)
423: IGA_AD_KNK[5] (in degrees; knock detection/timing pulled on cylinder 6- Just pick 2 Cylinders to log)
540: RFP_AV (bypass valve %)

For B8.5:
Group Number: Parameter Field (Units; details)
Group 2: Accelerator position (%)
Group 11: Charge air pressure specified value (hPa)
Group 24: Engine speed (rpm)
Group 134: Air mass (kg/h)
Group 226: Ignition angle; actual (degrees)
Group 228: Intake air temperature (in degrees C)
Group 230: Intake manifold pressure; absolute (hPa)
Group 480-485: IGA_AD_1_KNK_x (knock correction in degrees; x is cylinder number 0-5)
Group 616: RFP_AV (bypass valve %)



Step 10: Save the parameter list so you can easily access it at a later time by clicking the "VCDS" icon in the top-left corner. Name the file “performance” or similar. If you have parameter files for other types of logging, name them appropriately.


Logging
Step 11: This step is very important for capturing good logs. Press the “Turbo” button, and check the “Group UDS requests” box at the top of the screen. This will speed up the logging, and also group all 10 fields to the same timestamp. This is the only way to get useful logs (otherwise, each parameter will have a different timestamp).


Step 12: Press the “Log” button to initiate the logging session. This will not start the actual logging process
*Note: Your car should be running if it is not already.

Step 13: When you are ready, press the “Start” button. This will start the actual logging process.
*Notes:
-Logging should be performed in a controlled area where you can safely reach 85-90 MPH. The drag strip or dyno are the best options, but in places like Texas there are some pretty safe places to do this on the road (I do it late at night in traffic free areas with 70+ MPH speed limits).
-Logging runs should capture a full 3rd gear pull at a minimum. 4th is probably a little better, but that should only be done at the drag strip or on a dyno. A full pull is around 3000 RPM to 7000 RPM. This can be tricky on a DSG car because you need to avoid triggering the kickdown switch at lower RPM’s. Play around with what works best, but the sooner you can get to full acceleration the better.
-When logging, the A/C and radio should be OFF, the windows UP, car IN dynamic mode if available, and traction/ASR OFF (hold traction button for at least 5 seconds to turn both off).
-Logging should be done on a flat surface, and if done multiple times it should be done at the same location and in similar conditions if possible. This makes comparing data more accurate.


Step 14: Once you have captured the needed logs, press the “Stop” button to stop the logging process, and “Done, close” when finished. The logs will be saved to the Ross-Tech/VCDS/Logs folder as a .CSV file (typically on the C:/ or wherever the Ross-Tech software is installed). It can be opened with Excel or similar.


============
That is it for capturing basic performance logs. The next post will cover some of the basics in regards to interpreting the logs.

============
In addition to logging the basic performance parameters listed above, VCDS gives the option to log many many other things.
*Some examples:
-If you are experiencing timing being pulled due to engine knock detection, you may want to log knock on each individual cylinder instead of just the 2 covered above. In that case you would want to log something like: accelerator position, engine speed, ignition angle; actual, and IGA_AD_KNK[x] on all 6 cylinders. Those 9 parameters may point to an issue with a specific cylinder.
-As you can see, accelerator position and engine speed are really needed every time so you have some reference point in the logs. Intake air temperature is also good to log as it will give a good idea on the conditions.
-More fields and examples are below (updated below).
====================
Update with additional fields:

Misfires:
If you are experiencing misfires, you may want to log misfires on all 6 cylinders to see where the problem is coming from. In that case you would want to log accelerator position, engine speed, misfires all cylinders, misfires cylinder X on all 6 cylinders. These 9 parameters may point to an issue with a specific cylinder, or a more general problem.

Some (low number of) random misfires that DO NOT result in a fault code are fairly normal. I see it on most 3.0 TFSI engines stock or tuned. With that said, Audi has dumbed down the misfire reporting threshold, so it is possible misfires could be causing a performance issue, but also not trigger a CEL. I don't have an answer on what constitutes a real problem.... Maybe others can chime in. In the most basic sense, if you see a CEL due to misfires, there is definitely an issue. If you see a low number of misfires and no CEL, it may be normal. If you see a high number of constant misfires, but no CEL, blame Audi for dumbing down the threshold and try to figure out the problem.

251- Misfires all cylinders per 1000 rpm 0
253- Misfires cylinder 1 per 1000 rpm 0
255- Misfires cylinder 2 per 1000 rpm 0
257- Misfires cylinder 3 per 1000 rpm 0
259- Misfires cylinder 4 per 1000 rpm 0
261- Misfires cylinder 5 per 1000 rpm 0
263- Misfires cylinder 6 per 1000 rpm 0


Lambda/Air:Fuel/EGT:
Lambda or Air:Fuel ratio is important to understand for a couple of reasons. The most basic is to ensure your engine tuning is optimal. This is obviously more important with aftermarket (non-OEM) tuning. If you want to see what "normal" is, log your car with the stock tune, and the specified values will give you a pretty good idea for different scenarios. Assuming fueling is sufficient, specific and actual should be fairly close. If the actual number is higher than the specified value, you will start running into issues (not good).

On that note, if you are running E85 or the fuel system near maximum capacity, it is a good way to determine if fueling needs are being met. Again, E85 or if you are mixing E85 with regular gas, could present an issue on the stock fuel system. E85 has (about 33%) less energy per part compared to regular high octane fuel, so it takes roughly 33% more of it to run your vehicle. This can tap out the stock fuel system pretty quickly if too much is used. To run strait E85, and upgraded HPFP would be required. The advantage of E85 is the higher relative octane (close to the equivalent of 105 octane).

020- Exhaust temperature 1 bank 1 460.0 ∞C
021- Exhaust temperature 1 bank 2 459.5 ∞C
238- Lambda probes actual; bank1 0.9971
13- same?
239- Lambda probes actual; bank2 1.0049
14- same?
244- Lambda probes specification; bank 1 0.9971
245- Lambda probes specification; bank 2 0.9971
246- Lambda probes specified; bank1 0.9971
247- Lambda probes specified; bank2 0.9971
(note that 244-247 seem to be the same thing, the specified Lambda value, so logging one is likely sufficient).

194-199: Knock sensor voltage

Table to convert Lambda to Air:Fuel ratios:


Fuel Pressures, Trims, and Injectors

87- Rail pressure actual
170- Rail pressure specified
22- Fuel pressure
187- Fuel pump, actual fuel pressure

Fuel Trims/Adaptations (%)
47- Long-term adaptation; bank 1
48- Long-term adaptation; bank 2
63- Short-term adaptation; bank 1
64- Short-term adaptation; bank 2

Injector Pulse Width (IPW in ms):
609- TI_1_HOM[0]
610- TI_1_HOM[1]
611- TI_1_HOM[2]
612- TI_1_HOM[3]
613- TI_1_HOM[4]
614- TI_1_HOM[5]
To calculate the injector duty cycle, it is something like: (RPM x IPW)/300=IDC


================

Just a quick update on the new version of VCDS (15.7.4). Several people have reported very low resolution when logging 10 parameters with Grouping/Turbo enabled. In my case, I was only getting a couple lines of data on an entire 1/4-mile pass.

Another member changed some settings as recommended by Ross-Tech, and it seemed to help. I've posted the changes he made below. If you are having issues with 15.7.4, you may want to try these changes.

http://www.ross-tech.com/vag-com/faq_4.php#4.8
http://www.ross-tech.com/vag-com/tou...on_screen.html

I changed the parameters as per the Ross tech link above



Blk Int affects the protocol timing. The current default value is 55. To get the highest sample rate possible in the Measuring Blocks screen, set this to 25. Note, however, that this may cause unreliable communications with some controllers.

Char lnt also affects the protocol timing. The current default value is 1. To get the highest sample rate possible in the Measuring Blocks screen, set this to 0. Note, however, that this may cause unreliable communications with some controllers.

[jran76]

Understanding the Logs
Accelerator position (%): Pretty self explanatory. In terms of performance logging, we typically want to look at what the car is doing under wide-open throttle (WOT). On most cars this is in the 93-95% range. It is perfectly normal for the car NOT to hit 100%. The car will adapt to the given range on each vehicle for accelerator and throttle positions.

Engine speed (RPM): Again, pretty self explanatory. This will give a good reference point in the logs when the car is at maximum performance/higher RPM’s. Like WOT, the best indicator of performance is going to be what the car is doing at higher RPM’s; say 3000-7000 RPM.

Charge air pressure; specified value (hPa): This is essentially what the ECU is requesting in terms of air pressure or boost in the case of the B8 S4 engine. This value is in hPa, and needs to be converted to PSI for more common interpretation. You also have to subtract the ambient air pressure to get the actual requested boost number.
*1 kPa=10 hPa
*1 hPa=0.014503774
So, to calculate the requested/specified boost:
Requested boost= (Charge air pressure; specified value hPa) - (Ambient air pressure kPa x 10) x 0.014503774
*On a stock tuned car, this value will be in the 12 PSI range max. Any boost over this amount will trigger the bypass valve, and be bled off.
*On a tuned car, this value can be as high as 17-18 PSI. The tuned cars request more boost than is possible to ensure there is no bypass. The goal of a tuned car is to use all the boost available without opening the bypass valve.

Intake manifold pressure; absolute (hPa): This is the actual amount of pressure in the manifold where the specified is the requested. So, like the specified value, it needs to be converted to PSI, and subtract the ambient pressure. The amount of actual boost will depend on the size of the pulley, and losses due to belt slippage or leakage, environmental conditions, elevation, etc.
Actual boost= (Intake manifold pressure; absolute hPa) – (Ambient air pressure kPa x 10) x 0.014503774
*A stock car will see boost in the 10-11 PSI range, but it will bleed off at higher RPM's.
*A stage 1 car will see boost in the 12 PSI range, but it should not bleed off at higher RPM's
*Stage 2 cars can see as much as 16-17 PSI. I have seen a max of 15 PSI, but that is in really high DA's and we're at about 600 ft. above see level (hotter/less dense air will make slightly less boost).

Air mass (kg/h): This is the amount of air the car is taking in via the intake. The environmental conditions and type of intake you have will effect this value. Obviously, more air can equate to more power, so the higher the better.
*I have seen the stock intake have around 1100 kg/h maximum in my logging (70F, 50% humidity, 2000 DA). Aftermarket intakes that use the stock airbox are in the 1100-1200 kg/h range, and aftermarket open intakes like the Roc-Euro and CTS are in the 1300-1400 kg/h range.

Intake air temperature (degrees C): Another one that is pretty self explanatory; just note that it is in Celsius. IAT’s have a big impact on performance. Higher IAT’s mean less dense air, less timing, and the chance of more knock/timing being pulled and other bad things like misfires. The lower the IAT’s, the better.
*During my logging (see conditions above), I typically see a max of upper 60’s with the stock airbox. With the CTS intake (open filter with heat shield), I typically see in the upper 50’s.

Ignition angle; actual (degrees): This is the total actual timing.
*A tuned stage 2 car on 93 octane should typically sees total timing in the upper teens or low twenties at higher RPM/WOT. On race gas those numbers can be in the mid to upper 20’s in some cases.

ING_AD_KNK_x (degrees): This is the amount of timing being pulled from the given cylinder (x) due to knock detection. The amount will wholly depend on the gas you use, the condition of your car, and environmental conditions. It is very possible (and good) not to see any timing being pulled.
*Something in the -3 to -4 degree range is “normal” in hot temps or with lower quality gas. I have seen timing pull as high as -7 to -8 degrees on my car which will absolutely kill power. High IAT's are usually the most likely cause. Once IAT's get into the 60C range, you will typically see some timing pulled, and you'll see those higher numbers when IAT's reach into the 80C range; especially when mixed with lower quality gas or lower relative octanes.

RFP_AV (%): This is the bypass valve opening percentage.
*A stock car will see significant opening because the car will typically make more boost than requested at higher RPM’s, and the rest is bled off—this is why stock dynos die off after 5000 RPM.
*A properly tuned car should see nothing here; 0%. Anything else means the car is not making max boost/power. There are some instances where a tuned car may bleed off boost. I’ve seen this happen on my 1-2 shift when I get wheel spin, and others have reported it when IAT’s get extremely high as a protection mechanism (Revo tunes seem to prefer this method as opposed to retarding timing).

==============

Here is a post from Spazz with some more details and log examples:
http://www.audizine.com/forum/showth...VCDS-logs-here

Here is Mike's Chipwerkes thread that has a ton of log file examples (and lots of discussion about logging if you're willing to read through a lot): http://www.audizine.com/forum/showth...rke-piggy-back

Here's a video Jones posted:
http://www.audizine.com/forum/showth...hlight=logging

A few more examples here:
http://www.audizine.com/forum/showth...hlight=logging

More discussion here in regards to different tunes:
http://www.audizine.com/forum/showth...hlight=logging

Unitronic logs:
http://www.audizine.com/forum/showth...light=VCDS+log

Revo logs:
http://www.audizine.com/forum/showth...light=VCDS+log

[saxon]

Great post and explanation, just wish there was better software for logging/graphing

[audistealth]

I wish we had an actively participating moderator to sticky this thread, or add a link to a how to sticky thread.

[aaronz]

Here are the most recent blocks and descriptions for a b8.5 on latest version of VCDS as of 8/18
002 - Acl position
534 - Maf_cyl
227 - Intake manifold pressure absolute
473
474
023 - Engine speed
223 - Ignition advanced actual
225 - Intake air temp
597 - Rfp_av


Any more than that and I tend to get N/A values.




Sent from my iPhone using Tapatalk

[infinkc]

Excellent post! Thanks for taking the time to put this together.

[jran76]

Great post and explanation, just wish there was better software for logging/graphing

Agreed. It's not what I am used to in terms of logging, but it works for the most part.

Here are the most recent blocks and descriptions for a b8.5 on latest version of VCDS as of 8/18
002 - Acl position
534 - Maf_cyl
227 - Intake manifold pressure absolute
473
474
023 - Engine speed
223 - Ignition advanced actual
225 - Intake air temp
597 - Rfp_av


Any more than that and I tend to get N/A values.

Thanks. As I mentioned buried in the post, more than 12 values in normal logging will yield "N/A" values. Same goes for more than 10 when you use the "Grouping UDS requests" option, which is really a must. So, at the end of the day, you are really limited to 10 parameters for good logging.

I have 3 different logging parameter files: one for basic performance logging like I mention in the post, another for knock detection on individual cylinders, and another for misfire detection on each individual cylinder. There are still a lot of other things you could log depending on what is happening.

Excellent post! Thanks for taking the time to put this together.

No problem.

[VDub28t]

Thanks for putting this together.

[saxon]

Does anyone have a way of saving certain parameters so you don't have to check them every time?

Edit : nevermind, I see you already show how to do that

[Moose201]

Wow, great info. Why would the IATs be lower with an open intake? Seems like the stock airbox with snorkel to the grill would produce the lowest temp?

[jran76]

Wow, great info. Why would the IATs be lower with an open intake? Seems like the stock airbox with snorkel to the grill would produce the lowest temp?

I wish I had a great answer, but everyone that has logged various intakes has shown the open filters that have a heat shield to be 5C+ degrees cooler in most instances (Roc-Euro, CTS, USP). I think there are several factors. The stock air box, while sealed, still retains a lot of engine heat in the plastic itself. There is nothing that shields the box and intake tube from engine heat; the exhaust manifold is inches away. It shows that the heat shield is doing it's job, and you still have the same air feeding it through the stock snorkel. The three aforementioned intakes also take in a lot more air in general, which definitely helps.

[sergzz]

Subbed. Thanks for the great info, will do this tomorrow

[bgm130]

this should be brought to the top for people trying chipwerkz.
Jran I have used this thread and one on AR numerous times and its the easiest to follow. still forgot to hit turbo once or twice but thanks again for taking the time to make this guide

[bhvrdr]

This is a very helpful thread. Thanks to the OP for doing this!

Mike

[stereojorge]

this should be brought to the top for people trying chipwerkz.
Jran I have used this thread and one on AR numerous times and its the easiest to follow. still forgot to hit turbo once or twice but thanks again for taking the time to make this guide

Yup! About to use this with a buddy that just installed the Chipwerke piggy


Sent from my iPhone 6 using Tapatalk

[jran76]

No problem. Next time I do some logging, I'll add some updates in regards to new parameters and such. Shouldn't be long.

[jran76]

Updated with parameters from VCDS version 15.7.1. I also added the fields to log misfires and Lambda/Air:Fuel/EGT. If anyone has any input on changes, just let me know. I'm open to input....

[bhvrdr]

Nice job man. Should be stickied

Mike

[brainpan]

Amazing post you rock op! This will be handy when I go stage 2 next week

Sent from my Note 5

[Ze_Nardo6]

Great post. Extremely educational. Thanks.

[mrmomo313]

Nice job man. Should be stickied

Mike

Agreed

[14S4GWM]

Nice work

[jran76]

Edit: I added the below to the second post.

Here is a post from Spazz with some more details and log examples:
http://www.audizine.com/forum/showth...VCDS-logs-here

Here is Mike's Chipwerkes thread that has a ton of log file examples (and lots of discussion about logging if you're willing to read through a lot): http://www.audizine.com/forum/showth...rke-piggy-back

Here's a video Jones posted:
http://www.audizine.com/forum/showth...hlight=logging

A few more examples here:
http://www.audizine.com/forum/showth...hlight=logging

More discussion here in regards to different tunes:
http://www.audizine.com/forum/showth...hlight=logging

Unitronic logs:
http://www.audizine.com/forum/showth...light=VCDS+log

Revo logs:
http://www.audizine.com/forum/showth...light=VCDS+log

[skiptowncat]

Anyone run a log through virtual dyno yet, I found it to be failry accurate if used on a flat road

[Rolotuning]

Great post and explanation, just wish there was better software for logging/graphing

Does any one try datazap.me ?

[rtl5009]

Once work calms down (I work for Amazon, fuck Blackfriday through Christmas) I'll write a macro to automatically graph VCDS logs for everyone.

[rtl5009]

Additionally a conversion table isn't needed for AFR. Lambda is relative to stoich, and linear to boot! To get e85 AFR multiply by lambda by 9.9 and for gas AFR multiply lambda by 14.7.

Those are the stoich burn ratio for those fuels.

[jran76]

Once work calms down (I work for Amazon, fuck Blackfriday through Christmas) I'll write a macro to automatically graph VCDS logs for everyone.

Additionally a conversion table isn't needed for AFR. Lambda is relative to stoich, and linear to boot! To get e85 AFR multiply by lambda by 9.9 and for gas AFR multiply lambda by 14.7.

Those are the stoich burn ratio for those fuels.

That would be cool. I spend (waste) way too much time trying to graph things out. I usually add a column with A/F and boost calculated out as that's pretty easy, but I guess graphs aren't my specialty....

[AZT]

Additionally a conversion table isn't needed for AFR. Lambda is relative to stoich, and linear to boot! To get e85 AFR multiply by lambda by 9.9 and for gas AFR multiply lambda by 14.7.
Those are the stoich burn ratio for those fuels.

That would be cool. I spend (waste) way too much time trying to graph things out. I usually add a column with A/F and boost calculated out as that's pretty easy, but I guess graphs aren't my specialty....

And I personally just multiply by 14.7 no matter the gas or ethanol concentration, because it normalizes to a richness scale that people generally understand. Otherwise if you want to get technical, 14.7 isn't the right stoich for most people in the country on 10% ethanol gas where it is more like 14.1. And I may run 30-35% ethanol with my APR which probably has some stoich of 12.5:1 or who knows what on a given day.

So then some hot rodder on the street asks me what AFR my APR tune is running at full boost. I can tell them 0.78 lambda which may get a blank stare, I can tell them the true AFR of 9.7:1 (0.78x12.5:1) which may get laughs that my tune is way too rich, or simply convert 0.78x14.7 on the gasoline scale and say "11.5:1", which most people understand how relatively 'rich' that is.

[jran76]

Updated. Added fields for logging fuel pressure, trims/adaptations, and injector duty cycle.

[bhvrdr]

Updated. Added fields for logging fuel pressure, trims/adaptations, and injector duty cycle.

REALLY nice work jran. This thread should be stickied. I would only make one small correction which is about calculating duty cycle. The calculation you used is for calculating port fuel injection. For DI you have only 1/4 the time to inject so I assume you would divide by 300 and not 1200. For example, for port injection you have 20ms on-time at 6000rpm being at 100% duty cycle but for DI you would have only 5ms to inject that fuel at the same rpm.

http://forums.vwvortex.com/showthrea...-brief-results

Excellent work.

As an FYI there are also channels for load and a channel for injector status. The load one is nice to use in place of throttle position and the injector status is a nice one just for grins as it tells you when the car is running open/closed loop.

Mike

[VenturiRS]

subscribed.

This will come in handy.

[jran76]

REALLY nice work jran. This thread should be stickied. I would only make one small correction which is about calculating duty cycle. The calculation you used is for calculating port fuel injection. For DI you have only 1/4 the time to inject so I assume you would divide by 300 and not 1200. For example, for port injection you have 20ms on-time at 6000rpm being at 100% duty cycle but for DI you would have only 5ms to inject that fuel at the same rpm.

http://forums.vwvortex.com/showthrea...-brief-results

Excellent work.

As an FYI there are also channels for load and a channel for injector status. The load one is nice to use in place of throttle position and the injector status is a nice one just for grins as it tells you when the car is running open/closed loop.

Mike

Mike, thanks for the link and details. A couple questions just because I'm trying to understand this.... I'm not questioning you at all, but it seems like you've spent some time looking into this. Where did you get the 1/4 the time to inject from on a DI engine compared to a PI engine (or divide by 300 instead of 1200)? I've been reading up on this today, and I can't find anything too conclusive. No doubt there is far less time to inject, but is that 1/4 the amount of time something that is well established or more of just a general estimate.

You're definitely right in that it is much lower than the 1200 number used for a port injected engine, but 300 seems a little low for our engine (it is a lot closer for sure). That number seemed spot on for some of the DI examples I found, but they seemed to run a slightly shorter pulse width. The examples I saw were in the 0.4ms range at idle, and 5ms maximum. I didn't do a lot of logging on this last night (I was trying to log other things), but at idle we are around 0.6ms to 0.7ms. Under normal load, I was easily seeing 7ms-8ms which seems higher than I found in the examples. I didn't get a chance to test out WOT/high RPM's, but I will today....

I read a lot of things that basically said trying to calculate the injector duty cycle of a DI is not really possible, or at least not to do so accurately. I would assume this is because so many factors go into it, and fuel pressure plays a key role beyond just what the injector is doing (i.e. the injector runs close to 100% or the pulse width stays about the same, but the fuel pressure is raised as more fuel is needed).

I've logged load many time before as value 149 (did it last night while I was logging), but I have not done the injector status. Do you know what value # that is, and what it means?

[bhvrdr]

Hi Jran,

When I was first reading up on DI back then I purchased the Bosch Gasoline Engine Management Manual...

http://www.amazon.com/Gasoline-Engin.../dp/0470057572

Its still one of my favorite books. That is where I got the 1/4 amount of time. I agree, that there are more variables at play though. I can grab the page number when I get home if it is not packed up (moving soon). The gist is that with DI during homogeneous operation, the fuel must be injected in the induction stroke. So you have only half the crankshaft rotation available for the injection process. For port injection you have 2 full crankshaft revolutions available. That is 4 times as long. Still...would be great to hear from some of the gurus.


I'll grab the channel for open/closed loop mode. If memory is serving it is actually labeled oxygen sensor status or something like this. It is a trivial channel to log except to gain an understanding of how this Simos engine management is working in that it is almost 100% in closed loop mode which is far different than many other manufacturers. For this channel you can basically start the car cold and then go to warm condition and then do some driving in different conditions and chart what mode the car is in (closed/open). Not really useful except to gain understanding of the system.

Mike

[jran76]

Hi Jran,

When I was first reading up on DI back then I purchased the Bosch Gasoline Engine Management Manual...

http://www.amazon.com/Gasoline-Engin.../dp/0470057572

Its still one of my favorite books. That is where I got the 1/4 amount of time. I agree, that there are more variables at play though. I can grab the page number when I get home if it is not packed up (moving soon). The gist is that with DI during homogeneous operation, the fuel must be injected in the induction stroke. So you have only half the crankshaft rotation available for the injection process. For port injection you have 2 full crankshaft revolutions available. That is 4 times as long. Still...would be great to hear from some of the gurus.


I'll grab the channel for open/closed loop mode. If memory is serving it is actually labeled oxygen sensor status or something like this. It is a trivial channel to log except to gain an understanding of how this Simos engine management is working in that it is almost 100% in closed loop mode which is far different than many other manufacturers. For this channel you can basically start the car cold and then go to warm condition and then do some driving in different conditions and chart what mode the car is in (closed/open). Not really useful except to gain understanding of the system.

Mike

Good deal, thanks for the response. What you're saying definitely makes sense about when and why it fires the injector so much faster. 300 would make sense based on that, but it just doesn't seem to add up when you calculate it out (I'm getting IDC's close to 150% with that).

andthen is seeing a max of 8ms at around 5200 RPM. Using 300 as the dividing factor, you'd get over 138%. The interesting thing is the IPW went down as RPM's climbed past there. Either fuel pressure is making up the difference, or it was going down because his bypass started to open some. Oh well, we'll do some more testing to see how things look in the name of trying to learn something....

[bhvrdr]

Good deal, thanks for the response. What you're saying definitely makes sense about when and why it fires the injector so much faster. 300 would make sense based on that, but it just doesn't seem to add up when you calculate it out (I'm getting IDC's close to 150% with that).

andthen is seeing a max of 8ms at around 5200 RPM. Using 300 as the dividing factor, you'd get over 138%. The interesting thing is the IPW went down as RPM's climbed past there. Either fuel pressure is making up the difference, or it was going down because his bypass started to open some. Oh well, we'll do some more testing to see how things look in the name of trying to learn something....

Thanks for sparking the interest again. Yeah, as we exercise these cars on e85 and with dual pulleys and stage 3 setups these things will start becoming more relevant. I'd like to hear from the top tuners what they were discovering during things like e85 testing. I suspect they would just be logging AFR and Rail pressure more than anything to see if the fuel system is keeping up. Interesting learning more about this ECU. I need to do some more studies on the fuel trims too. I cant believe how good this car is at keeping up with extra demands.

Mike

[xpoweruk]

Ok just found the newer thread.
I did my first data log totay
Not sure if it is of use or not

2011 S4
Revo stage 1+ (pulley upgrade version )
Revo intake
Milltek ValveSonic exhaust

https://www.dropbox.com/s/9y6zyz4osz...-1941.CSV?dl=0

[Mat@1975]

Ok just found the newer thread.
I did my first data log totay
Not sure if it is of use or not

2011 S4
Revo stage 1+ (pulley upgrade version )
Revo intake
Milltek ValveSonic exhaust

https://www.dropbox.com/s/9y6zyz4osz...-1941.CSV?dl=0

Hello,

It seems that you did not choose the UDS group request and Turbo! options.
You did not logged mandatory things like % accelator position and rpm....

I suggest you to take a little time to read this excellent thread where all is perfectly explained.

BR

Mat

[xpoweruk]

will do,found it after logging :(

[BlownOne]

Awesome post with a ton of great information!!!👍🏼