My most recent datamaster log has a few weird things that I would like to clear up. My LTerms and STerms seem to deveat while crusing from 128 while in Closed Loop. WOT and Open Loop are fine. Is this normal? Can someone look at it to let me know what is going on. I have TunerCat so I can change stuff if someone has something to throw at me

log file

 

anyone?

 

I don't have datamaster so I can't view your log, but when you say deviate from 128, what kind of values are we talking? It's normal for your long term and short term fuel trims to go a little over or under 128, it just means your computer is adjusting for a lean/rich condition. They also jump around depending what fuel cell you're in, example: they might be 124/124 in cell 16 (idle), but 120/120 in another.

Scan the car again and record the long term fuel trim values for both passenger & driver side over several different cells.

 

Well, your Lterm BLMs are getting a bit low in a few areas and look to be bottoming (108) a couple times during the log. This indicates that the O2's are reporting a rich condition causing the PCM to pull fuel to try to correct.

If it were me, I'd try to figure it out. It really isn't a big problem, because, for the most part it is still within the PCMs ability to correct, but it is on the edge of becoming a problem if it bottoms out any more.

How fresh are the o2 sensors? Have you played with the MAF at all? Who did the tune and was it done on a dyno?

If the O2 sensors are in good shape, then you should be able to tune around it to get the BLMs back in the middle somewhere (near 128) so that it has adjustment range again.

You might want to export the pertanant info to .csv format so some of the members that don't have Datamaster can view as well (Fred being one of them that doesn't use DM).

 

If you don't understand why the BLM's move as you make subtle changes to throttle position or RPM, and don't know why the short terms are jumping around as fast as the O2 sensor readings, you haven't read, or didn't understand my ScanMaster writeup. All of this is explained in the "Air/Fuel Management" section. You might want to take a look at it. If you have anyh questions after reading that, I'll be glad to answer them.

Also, by posting your data log as a ".uni" file you are limiting the people who can look at it to DataMaster owners. "export as .csv" and all of us can look at it and analyze it using Excel.