At the time of this writing, the engine idles pretty much flawlessly and tweaking some cells in the VE Table improved reving somewhat before I fumbled. Don’t ask me how, but I loaded and burned a previously saved msq file when I was switching back and forth between MegaTune and TunerStudioMS. I had done that a few times earlier, but I must have clicked ‘Yes’ to the question. At least it’s not like starting COMPLETELY over.<\/p>\n
There are a couple of things going on that do not seem right. Most troubling is very flakey signals from the O2 sensor. It mostly stays pegged at 5 volts (or AFR 21.9, depending on which gauge you’re looking at), but will occasionally scatter like a crazy monkey. It was working well earlier in the day, at least returning believable numbers. Wiring looks good. I will try to locate or replace the programming cable and verify that the LC-1 is programmed correctly.<\/p>\n
With essentially no O2 sensor, I’m tuning kinda blind and my nose says it’s rich at idle and my ears say that it leans out around 4000 RPM. Right before I shut down for the evening, I made a log file of a short run.<\/p>\n
The first thing that was less obvious in MegaTune is a pulsing 5 KPa swing in Map at idle. This pulse occurs 6 or 7 times in most logged seconds, which corresponds with the expected vacuum pulses at idle. My vacuum signal is from one TB, which feeds two cylinders. (850 rpm \/ 2 cylinders) \/ 60 seconds per minute = 7 pulses per second. I recall a mention of such pulsing making tuning difficult and a damper made by restricting the vacuum signal slightly and following the restriction with some kind of accumulator, such as a clean, dry fuel filter. I will implement such an accumulator.<\/p>\n
In the mean time, I will continue analysing the log file.<\/p>\n
In a more entertaining note, it’s interesting to see single isolated MAP readings of 159 or so, which I presume correspond to backfires. Early in the first start process, when it was beginning to have a useful amount of fuel but was still too lean to run, I had a few spectacular backfires. One of them actually popped one side of the throttle body out of its rubber boot!<\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":"
At the time of this writing, the engine idles pretty much flawlessly and tweaking some cells in the VE Table improved reving somewhat before I fumbled. Don’t ask me how, but I loaded and burned a previously saved msq file when I was switching back and forth between MegaTune and TunerStudioMS. I had done that … Continue reading Sunday Night Analysis<\/span>