What might cause an inaccurate report on my datalog? I'm tuning an ARAP based 6e, and every so often I'll notice something obviously out of whack. Sometimes the desired idle will report wrong, sometimes it's something else. The example below is a snapshot of a reported 43.24 advance (column H) when in reality my actual table isn't anywhere close.........see attached.

The columns are (in order): Veh speed, RPM, TPS, BLM Cell, BLM, INT, LV8, Timing, MAF

I'm totally lost on this........... could there be an address problem of some sort?

 

Does anybody have any ideas on this issue? The crazy thing is the very same datalog shows a correct timing pattern in the same light cruise area later on in the report. See below for a comparison, I'm totally lost.

 

what was the coolant temp at the time when it was reporting 43.24?

 

Hummm, good thought. I'll check it when I get back home tonight & repost. Thanks!

 

i just checked my datalogs, the temp was a rock solid 192.2 the whole time.

 

something must have been causing the PCM to command more advance... TP can't log "inaccurately" like that, it only reads the stream and converts hex values into real-world values.... so the PCM was commanding more advance, the mystery here is what was causing it. look around at any other values, see what's different other than advance in the same conditions.

 

I had a chance to look at that D/L again & I can't find any conflicting values in those examples except for the timing entries. In previous D/L's I've also noticed an occasional misreporting of timing similar to this one. In the past, I've also noticed that my desired idle report will vary sometimes between 700 and 800 RPMs from datalog to datalog.

Could this be a problem with the ECM?

 

IMO, it's not a misreporting.... it's actual advance, but for some reason it's varying.

without pouring through a log, i wouldn't know for sure, but i highly doubt the advance shown in the datastream and the actual advance commanded are different.

 

OK, thanks! Can you give me any idea what to look for in my logs? The only place I've seen this is with a rich condition of 118. I have some 120 & 124 BLMs but they seem to show correct parameters within the advance table. I looked at knock counts & retard, but there's nothing there either.

Also I'm pretty new to this, is looking thru an excel file like I'm doing the best way to analyze these logs? Thanks a lot for your input!

 

yes, an excel file will allow for some very quick comparison to get an idea of what all is happening...

if you want a second opinion, email the log to me

robertisaar at yahoo .com

 

Wow, what a generous offer, many thanks! I'll do that when I get home tonight.......I'll send the current bin along as well. Thanks again,

Tim

 

Check your highway mode spark advance. It may explain what you are seeing. Coolant compensation is another possibility.

 

As tequilaboy suggested in the previous post, and as Saar discovered looking over my log it turned out to be the highway spark triggering add'l advance based on the LV8 plateau. Thanks to Saar for taking the time to help this noob & thanks to tequilaboy for his great suggestion.

You guys are amazing!