kael

Finally got my ALDL/OBD1 datalog working well on my '87/L98 and collected a 20 minute trip. Of course, this leads to the question, what am I looking at and what is bad/good?

Any pointers for learning? Google says, "What?"

I know, it's adx/whatever specific, but "MAF Flow Rate" I can guess, I'm chasing what is a bad value.

tequilaboy

Can you zip and post the log file here?

Without WB data, logs are typically evaluated by the fuel trim behavior (BLM and INT), Narrow band O2 behavior, trouble codes and presence of knock counts/knock retard.

In general, you want to see reasonable consistency of BLM values across all active cells and approximate BLM values of 128 +/- 12 or so.

vader86

Difficult to list them all out and give a range for every number that is in the log. There was a forum post here long ago that had that.

Basically I looked at TPS and IAC to observe idle behavior, how the O2 mV fluctuates and whether its dropping out of closed loop, knock counts and the timing that was requested to decide whether my tuner needed to pull back, and the BLMs need to average out around 128.

tequilaboy

Here's another cool way to share and view logs (just need to export to csv and cleanup the file a bit first):

https://datazap.me/u/tequilaboy/feli...zoom=7652-8538

This is the same data from the example log that was included in my original zip. Zip has been removed due to little interest. Selective export to csv and minor file cleanup for easier viewing in datazap.

Note: Open link in Chrome or Firefox, IE may not work according to info from datazap.

Dt86

What hardware/software are you using? I'm just getting started with this myself. I'm using tuner pro rt and a moates apu1.

kael

Odd, I only got one notification from this thread via subscription.

Zipped log attached. Probably means little, issue I'm chasing is why #2 is fouling its plug. Important note, this was collected with diagnostic mode disabled...I think. Using 1320 BT in 8192 baud gets a little odd there.

I'm playing around in spreadsheet charts (Libre Office! MS sucks!).
tequilaboy, you meant INT for "BLM values of 128 +/- 12 or so", yes?

tequilaboy

I would have preferred to see the xdl file, but csv will work for our purposes.

Here's a plot of your log in datazap with a few basic signals displayed:

https://datazap.me/u/tequilaboy/kael...18-19-20-28-29

Looks pretty good, overall. A few knock counts here and there. BLM ranges from 115-143, so there is some room for improvement.

Areas of concern: lean tendency in cells 14 and 15. Elevated INT and BLM increasing and not yet stabilized (not enough data)...BLM may continue to increase in these cells. Some risk of going lean in PE mode depending upon maturity of fuel trim. Use caution as load/flow is increased.

tequilaboy

Your INT and BLM signals are both pretty choppy. In order to get a better picture of the overall fuel trim behavior, I added a new signal: "trimsum" = (INT+BLM-128).

This signal gives an idea of the overall fuel correction. You can see that the O2 is not really being driven by the fuel trim. It is more random with greater frequency, which suggests there is some disturbance affecting the mixture.

example here:

https://datazap.me/u/tequilaboy/kael...00&tmax=183.00

kael

Cylinder #2 keeps fouling spark plugs, may be part of the cause. Been chasing that things problem for a year and a half, down to the most likely, worn or stuck rings. Unsettling though, runs fine, no oil loss until the plug fouls.