Best Parameters to Log for Shared Data

[Ze_Nardo6]

There is a very well written thread in this forum that discusses VAGCOM and how to run logs, etc. That is not the point of this thread.

In this thread I want to discuss the 10 best parameters to log that will best help members compare data with different tunes, setups, etc. Also, for myself and I'm sure for others, to discuss what those parameters measure exactly. Some are more obvious than others.

When I was asked to send logs to my previous tuner, he requested Lambda Probes Actual bank 1 and bank 2. Have no clue what those specify but would like to open a discussion.

Here are some I would assume are pertinent:
1) Engine Speed (actual? what's the difference?)
2) Boost (actual)
3) Boost (specified)
4) Intake air temperature

What else is best to group with the above? If you could provide an explanation as to each parameter that would be great. Thanks

[AudBoost]

Definitely want to log
1) Ignition angle - degrees of timing shows how aggressive the tune is
2) knock detection - If you are seeing knock than the tune is too aggressive or you have insufficient octane. See #1 for how much timing is being requested
3) Bypass valve percentage - Ideally this number should be at 0 on a tuned car. If you are bleeding boost see #2
4) AFR (Lambda) - Want to make sure you car is not running too lean. nothing like a fried piston.
5) EGT - Very high exhaust temps are a sign of an issue. see #4 to make sure the car is not running lean
and for those guys running E85 you would want to log
1) actual rail pressure
2) actual fuel pressure
3) Short-term adaption

[jran76]

There is a very well written thread in this forum that discusses VAGCOM and how to run logs, etc. That is not the point of this thread.

In this thread I want to discuss the 10 best parameters to log that will best help members compare data with different tunes, setups, etc. Also, for myself and I'm sure for others, to discuss what those parameters measure exactly. Some are more obvious than others.

When I was asked to send logs to my previous tuner, he requested Lambda Probes Actual bank 1 and bank 2. Have no clue what those specify but would like to open a discussion.

Here are some I would assume are pertinent:
1) Engine Speed (actual? what's the difference?)
2) Boost (actual)
3) Boost (specified)
4) Intake air temperature

What else is best to group with the above? If you could provide an explanation as to each parameter that would be great. Thanks

Lambda is essentially your AF ratio. A reading of 1 is equal to stoich or 14.7:1 (that number will drop as ethanol content increases). Audi tunes the car to target around 0.9 Lambda readings, or maybe a little lower. Most tuners seem to go for something in the 0.8 to 0.85 range. There is a chart to convert Lambda to AF in my logging thread.

What I'd log really depends on what I am after, but in general, these are good:

Accelerator position (%)
Engine Speed (RPM)
IAT (intake temps in *C)
Air mass (air flow in kg/h)
Specified pressure-MAP (hPa)
Actual pressure-MAP (hPa)
Ignition timing actual (timing in degrees)
Knock correction on a cylinder (in degrees)
Lambda on one bank
Bypass (%)

Unfortunately, at least for me, those aren't set in stone. I like to log knock correction on at least two cylinders. I usually remove lambda once I know what it is on my current tune or with the gas I'm using. I also like to check for misfires from time to time, so I may add that in. As mentioned above, for E85 I'd log completely different things. I don't want to rehash my logging thread, but you get the idea. Strictly to compare, the things I listed above are good.

[Ze_Nardo6]

Definitely want to log
1) Ignition angle - degrees of timing shows how aggressive the tune is
2) knock detection - If you are seeing knock than the tune is too aggressive or you have insufficient octane. See #1 for how much timing is being requested
3) Bypass valve percentage - Ideally this number should be at 0 on a tuned car. If you are bleeding boost see #2
4) AFR (Lambda) - Want to make sure you car is not running too lean. nothing like a fried piston.
5) EGT - Very high exhaust temps are a sign of an issue. see #4 to make sure the car is not running lean
and for those guys running E85 you would want to log
1) actual rail pressure
2) actual fuel pressure
3) Short-term adaption

If running e85, where should values be for: (and how does this compare to where values should be if running 93?)
1) fuel pressure
2) fuel rail pressure

What does short-term adaption measure?

[jran76]

If running e85, where should values be for: (and how does this compare to where values should be if running 93?)
1) fuel pressure
2) fuel rail pressure

What does short-term adaption measure?

I'd have to look at some logs to give you the fuel pressure values, but I'll try to look later today.

Short and long term adaptations are essentially your fuel trims, or how much more/less fuel is required to hit the target Lambda. Long-term is just that; the calculations based on some number of driving cycles. Short-term is the current adjustment that will continually change on top of the long-term. The reason you want to log this if you are running E85 (or a mix of) is because it requires so much more fuel. There is a certain limit to the adaptation values. Day-to-day, you probably don't want to see those over 10%, and I've been told there is a certain threshold you don't want to cross in the 25% range. If tuned properly, those numbers should be closer to 0%.

[jran76]

For fuel pressures:
The stage 2/93 tune logs max out around 13600 kPa (1970 psi), and the injector pulse width maxes at 6.2ms at 6200 rpm.

The stage 2/E85 tune logs max out around 14250 kPa (2066 psi) and the injector pulse width maxes at 8ms at 5200 rpm.

The fuel rail pressure should read really close the the fuel pressure, but it's measured in hPa. The logs I have show it within 1% pretty much at all times other than a few transitions where it jumps around a little.

[14S4GWM]

This is very useful Jran, thanks.

http://www.audizine.com/forum/showth...rmance-Logging

[Ze_Nardo6]

This is very useful Jran, thanks.

http://www.audizine.com/forum/showth...rmance-Logging

I just saw the second post in that thread. Some really great info Jran, thanks!

[jran76]

I just saw the second post in that thread. Some really great info Jran, thanks!

At some point soon, I'll add some more detail like what I mentioned above..... Some of the current descriptions probably need minor updating too, but they'll get you close.

[AudBoost]

Jran your logging thread should really be a sticky. Very useful! Thanks for putting it together.

[jran76]

I think everyone has pretty much given up hope that we'll ever have a moderator for this section.