Learning to read data logs

I have spent many hours reading and looking for info on datalogging and while I have learned a little, I still haven't found out how to tell if there are problems in the tune/engine. I understand it isnt always cut and dry, but where do I educate myself to be able to do this. There have been times that I look at data logs and think there are problems just to post the logs and have people tell me they are minor or nothing to worry about. For the time being I'm not so interested in being able to create a tune as just being able to evaluate it, and possibly tweak it. Everyone says to read the stickies but I other than the one about Knock, they haven't been all that helpful or it seems like 2 pages of useful information are stretched out over 50 page threads.

I guess the main question is how/where did many of you guys learn what you know? I've looked at the forums both here and at RR but cant really find a good thread or section of a forum to learn from. Is it really as hard as going through 50 page threads just to get a couple nuggets of usable information?

I see plenty of members who are willing to evaluate logs, and I thank all of you btw, but I and many others would like to be able to do the basics ourselves? I'm not expecting a single thread to replace years of training/schooling, but is being able to check if the engine/tune is ok that complicated?

Specific things that I'm hoping to learn:

What are acceptable ranges for the different parameters that are logged to evaluate an engine and tune on a stock or lightly modded (i.e. stage 2) car?

What is happening inside the engine when values are outside of that range?

What tables need to be edited to bring those values back to acceptable ranges?

Good luck. It is great that you want to learn, but there is no simple way to answer your question. To be able to correctly interpret logs from any engine you have to understand how an engine works and what the tune is trying to accomplish. Unfortunately, the vast majority of people on forums havae literally no idea what they are talking about, so it can be confusing. Then they start arguing with each other in what is typically a pretty funny yet sad interaction.

The best advice is to read some books on engine theory (there are several and they have been listed many times) and more importantly, try to figure it out yourself by looking at logs of your own engine. Your best bet is to find someone who knows what they are doing and learn from them; of cousre if you find someone who is clueless, then you will have to sort that out as well

The good news is that it is not all that hard, just more than someone is going to type on a forum.

I learned from reading and asking a lot of questions..and I still have a lot to learn.

First thing you should do is read this, it is pretty short and gives a really good summary:

Tuning Guide: http://web.njit.edu/~trb2/WRX/download/

Also read this: http://forums.nasioc.com/forums/showthread.php?t=1626520&highlight=tuning+guide

I think seeing if a tune is safe is reletively easy. My definition of safe is that it is not knocking..period. Since you have a stock knock sensor and you know your timing and boost adjusting a tune to make it safe is pretty easy. The only real unknown is your AFR (unless you have a WB02), and assuming you have your stock airbox, fueling should never be way off.

Assuming you are running a stock airbox, you could start with a MickeyD stage 2 tune, you could feel comfortable knowing that the fueling is very safe and that timing is also pretty conservative.

All you need to do is log:

Engine Speed

Engine Load

Knock sum

manifold relative pressure (corrected)

WGDC%

Total Timing

Throttle opening

You do a 3rd gear WOT run from 2000-redline and then review your log.

The 1st thing I do is look to see if knock sum increased during the run, then I look to see that I am not overboosting. If you are over boosting you will need to adjust your WGDC, if you are knocking you need to reduce timing in the region of the map that you got the knock.

After you get past this basic health check on a tune youa re ready for the more detailed/fine tunning.

This is just my way of doing it, I am sure there are safe ways to tune, but this way works for me and I think it is a ood way to determine if you tune is safe and allows you to adjust it if it is not.

Just looked through the tuning guide, got a lot of research and reading ahead of me.. Got a few questions on checking a tune.

I noticed spec B didn't list FBKC or FLKC in the list a parameters, are these more for tuning than checking for a safe tune?

How do I spot overboost and at what level is it a concern?

Driving around I've noticed my knock sum climbing, but I don't see it rise at WOT, is this normal? I remember the car manual saying that some knock is normal.

FBKC and FLKC are 2 of the 3 way the ecu deals with knock and pulls timing, the 3rd is IAM (rough correction). All 3 are reactions to knock.

Knock sum is a counter of your actual knock events. So if you log knock sum, you are logging the actual knock activity, not the ecu's response to the knock (the timing pulled be FBKC and FLKC).

FLKC is captured in your Learning view, so is IAM. The point is..FBKC and FLKC both rely on the knock signal (knock sum) to tell them what is going on. When you log Knock sum, you get a much clearer picture of when you are knocking.

Overboost is very easy to check you go to your boost target map and compare it to your log. If your target is 16psi at 5,000 rpm and you are hitting 14, you are underboosting. I do not like to see more than .75-1psi overboost from my target..

Low RPM, low load knock is completely normal; in fact, most tuners do not change anything in that region of the timing and fuel maps, it is the same as stock. I get 5-6 knock events just pulling my car out of the garage.

If there is no knock sum increments while under WOT from 2000-redline, you can pretty confidently know your tune is pretty safe.

I get 5-6 knock events just pulling my car out of the garage.

 

If there is no knock sum increments while under WOT from 2000-redline, you can pretty confidently know your tune is pretty safe.

Likewise, and it took me a while to get used to this being normal. Backing out my garage/driveway could be 0 - 5 knock events. A 30 min drive could be another 20-30 knock events. Hundreds of wot logs starting at 2k in 2nd, 3rd and 4th gears show no knock though.