VagCom Profiles & Instructions For Testing Gasoline, Spark Plugs and Water Methanol


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VagCom Profiles & Instructions For Testing Gasoline, Spark Plugs and Water Methanol

With all of the performance hardware and software combinations available today, each vehicle becomes more and more custom, straying farther and farther away from a standardized dataset or a “one size fits all” approach. Add in varying degrees of maintenance routines, different fuel availability and mileage and the vehicle’s VagCom data can vary wildly. Aside from the hardware, software and maintenance, choosing the proper gasoline in addition to the proper spark plugs (material, heat range and gap size) is vital to maximize power and efficiency. With a proper aftermarket intercooler, our goal should be to safely maximize overall timing advance and zero out or remove any correction factor / timing pull without the use of water methanol systems.

By lowering correction factor / timing pull with the choice of pump gas and spark plugs, water methanol users can then better tune their water methanol systems to run the least amount of water methanol needed to realize maximum overall timing advance with enough of an additional safety “buffer”. The first step is to test various gasoline fuel types and their effect on overall timing advance for your current software octane MAP. The second step involves testing spark plugs and various heat ranges and gap sizes to remove any leftover correction factor / timing pull caused by higher boost values -> higher cylinder pressure -> higher cylinder temperatures = prevent pre-ignition.

Over the past few years, there has been enough data collected on the forums to make generalized recommendations and some software manufacturers have even provided specific recommendations so everyone should not feel obligated to become their own diagnostician. For those who want to learn about their vehicles, you can test the hardware and software combination in your vehicle. To make things easier, I wanted to share my VagCom profiles, complete with instructions on how to properly monitor the overall performance of your vehicle. If you want to safely push your engine to its fullest potential, take the appropriate steps to ensure your setup is working as intended. There are SO many variables with every aspect of the setup that it’s always good to know they are all working properly. The majority of this thread is credited to Jamie@APR after the time he spent teaching me how to properly read spark plugs and my own VagCom data.

-This “how-to” is open to other ideas or facts which can be added to the initial posts.
-Specific spark plug recommendations can be added to the initial posts if manufacturers provide feedback.

The Greatest Guide to Reading Spark Plugs:

Spark Plug Feeler Gauge:
It is important to use a flat feeler gauge set to set the spark plug gap. With fine point spark plugs, care should be taken not to damage or deform the center electrode tip. Choose the exact size feeler for the spark plug gap you want and then choose the feeler that is .001" larger than your desired gap and just set it aside so it’s easily accessible. The exact size feeler should have a slight drag without feeling like its pinching. After you think you have the gap right, try inserting the feeler that is .001" larger. It shouldn't fit AT ALL. If it fits, tighten the gap more and recheck.

Spark Plug Gapper:
It is important to use a separate gapping tool to adjust the spark plug ground strap. Use only the fork ends to bend the spark plug ground strap to open or close the gap, like seen in the image below. It is ok to tap the ground strap on a smooth, hard, flat surface to lower the gap as well. Take care not to knick or mar up the spark plug ground strap. Creating sharp burrs on the flat surface of the ground strap can cause hotspots to occur on the ground straps surface and could promote pre-ignition.

Data Logging Guides (alphabetically):

Timing, Misfires & Boost VagCom Profiles:
-Click Here to Download Profiles-

Importing VagCom Profiles:
Select Control Module -> Engine -> Advanced Measuring Blocks -> Click VCDS icon (top left of measuring block list) -> Load selection to file -> Choose Profile -> Click Turbo! button at the top of the screen -> Click Log -> Click Start when you’re ready to start your WOT pull starting at 2,000 RPM in the highest gear you normally use under full load (3rd or 4th gear).

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Timing Profile for Gasoline Quality, Spark Plug Heat Range and Water Methanol:
This Timing Profile can be used to see how much correction factor (ECU reduces timing when it experiences knock) you are getting with your choice of pump gas or spark plugs. Test various gasoline options, specifically within the list found on Obviously, ambient temperatures will play a role in overall timing so try to keep your logging consistent (same time of day, same location, similar ambient temperatures). This Timing Profile can also be used again to validate the spark plug heat range choice based on correction factor results. For water methanol users, this Timing Profile can be used further to properly dial in your water methanol system to reach 0 correction factor after gasoline and spark plugs have been tested. The goal is to spray the least amount of water methanol to achieve 0 CF, then add a bit more just for safety sake. This minimizes how much the sensors and other components are subjected to water methanol and preserves your full tank. An occasional -1.5 CF here and there is fine but it’s always best to shoot for 0 correction factor so you get the most out of the available ignition advance requested by your software.

Misfires Profile for Spark Plug Gap:
This Misfires Profile can be used to test spark plug heat ranges and spark plug gap based on the misfire counter. It is recommended to run the largest gap per plug in a certain heat range. First log full throttle (WOT) pulls starting at 2,000 RPM in the highest gear you normally use under full load (3rd or 4th gear). If you experience misfires at full-throttle, lower the gap in 0.002” increments. This type of misfire is caused by the spark being unable to jump the gap with the cylinder pressure level it is exposed to.

Once the full-throttle pulls are free of misfires, the next things to monitor are misfires during idle at cold-start, during typical cruising and during idle at full operating temperature. Start the Misfire Profile log at cold start letting the vehicle idle for 5 min, then cruise around town/highway for 10 minutes, and then finally let the vehicle idle again at full operating temperature. You will be logging roughly 20 minutes of driving to check for misfire frequencies. The closer the spark plug gap, the easier the spark can jump the gap under both full throttle (WOT), idle and cruising conditions but this is also less spark “surface area” to ignite the mixture with. The goal is to obtain the largest spark plug gap which resists misfires at idle and does not blowout at full throttle (WOT).

The last thing you’ll want to do is just drive the vehicle like normal for a few days and then pull the spark plugs out to inspect them in order to see if they are self-cleaning. If the spark plugs seem to properly self-clean without a lot of buildup then the experiment complete.

Note About Misfire Counter Through VagCom:
From the factory, misfires can be registered occasionally on a vehicle but may not be a true misfire condition. This is caused by the threshold set by the manufacturer being VERY close to the actual monitored combustion level. If you see a rare ‘1 count’ on individual cylinders don’t be concerned at this level, as it could just be the monitored level just barely reaching the sensitive threshold without a full misfire occurring. If you hear audible misfires or exhaust “pops” during idle at cold start or you begin to log multiple misfires occurring (counter begins to climb above 1 or 2) and can be seen on more than 1 cylinder at a time, it is time to lower the gap in 0.002” increments.

Conditions Which Can Cause Misfires:
-Faulty or missing spark plug gasket (can cause airflow to occur at the tip of the plug and could cause spark blow out)
-Faulty oxygen sensor (allows excessive fuel to be supplied and unburned)
-Faulty PCV or valve stem seals (can cause excessive oil to accumulate on the plug as well)
-Fouled spark plugs
-Improper torque spec when tightening spark plugs (loose plugs can cause poor ground connection)
-Poor connection between the head and spark plug threads or using too much anti-seize compound (ground connection is made through the threads on the spark plug)
-Poor electrical connections or corrosion
-Weak or faulty ignition coil

Boost Profile for Leaks or Diverter Valve Options:
The Boost Profile can be used to check for boost leaks or test diverter valve options (OEM “D” DV, GFB DV+, etc). Watch the N75 duty cycle to see what the diverter valves are actually doing.


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Spark Plug Recommendations:
Stock turbo (no software), Stage 1 through Stage 2+:
PFR7S8EG Double Platinum (1675) (gapped at 0.032” from the factory):
BKR7EIX Iridium (2667) (gapped at 0.032" from the factory):

APR K04 V3.1:
BKR8EIX Iridium (2668) (gapped at 0.032 from the factory, re-gap to 0.026”)

Other K04:
PFR7B Double Platinum (4853) (gapped at 0.028”):
PFR7Q Double Platinum (7963) (gapped at 0.032 from the factory, re-gap to 0.028”):

APR Stage 3:

APR Stage 3+:
BKR8EIX Iridium (2668) (gapped at 0.032 from the factory, re-gap to 0.028”)


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I ran some this morning with water meth, tonight I run some without water meth in hotter temps to see how my top tier gas and 8 series plugs are running.

just for my information, what pull would be better 3rd gear or 4th starting at 1500RPM for both...ive heard of people logging both.


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Start your WOT pull at 2,000 RPM in the highest gear you normally use under full load (3rd or 4th gear). 4th gear is preferred as it's a longer pull and when using TURBO! mode in VagCom, the sampling rate is much better for more overall data to review. 4th gear requires a long stretch to safely run through 6,000rpm.