wacky fuel data

[cjowett]

So I took the truck out for a second test spin to log some data worth seeing. Pretty easy run. Started logging at the side of the road, accelerated fairly hard going up hill and then backed off. Drove fairly evenly for a bit, pulled over and paused logging. Started it up a couple of miles down the road to record cruze data. I have removed the cat and DPF (so second O2 sensor is missing) and just before I fired it up for the test drive I removed the Quadzilla boost fooller I had installed.
When I plotted the data I was surprised. My first chart showed RPM, boost pressure, main injector quantity and fuel pressure desired. Other than the boost pressure having a minimum value around 12 psi, boost, rpm and fuel pressure looked reasonable. Main injector quantity on the other was nuts. It starts out reasonably flat and then starts to spike up and down wildly, will level off a bit for a while and then go nuts again.
So I added a second chart: RPM, fuel pressure desired, main injector quantity, and main injection duration. Quantity and duration are both going nuts but not in a way where one compensates for the other, just uncontrolled fuel.

Have I uncovered a problem in the tune, confused the ECM by unplugging the fooller or O2 sensor or what the H is going on?

[cjowett]

So the latest logging exercise showed normal fuel data so I'm guessing the wackiness was due to unplugging the boost fooler.

[comnrailpwr]

When I tried logging through a cts monitor with a splitter it did that. Also when I tuned a LMM transit bus with a crap load of electronics on it it did that. It does that it seems when something else is trying to retrieve data along with scantool.