2014 Chevy Malibu 2.5 ecotec p0171 with freeze frame with very high LTFT

Here's some new and better 1/12/19 graphed screenshots from idle to higher RPMs

Tutti57 wrote: Wouldn't you still expect to see lower ltft than this at that rpm if there was an intake leak?

You'd think, right? I guess I was mostly wondering about the intake shifting around while driving. Was blown away that intakes were coming loose, more than anything! :lol:

Here's some new and better 1/12/19 graphed screenshots from idle to higher RPMs

Thanks! Those trims don't look that bad. :huh: At idle or 2500 RPM. Is it still setting the P0171?

Yes still throwing code. I did notice something I hadn't really paid much attention to beforehand, the car at idle is periodically making a small JET engine noise. I've read this could be intake leak causing this. I felt this could be a good thing to mention now that I'm noticing it. It's not super loud but the idle gets more rough when I hear the noise start. It's about every 15 to 45 seconds.

This one pattern reminds me of the misfire I was chasing recently.

I had this with a Holden Barina coil-pack. At first all I saw was the long "rich" part of the pattern which seemed to
be when the misfire occurred - but looking at the map sensor reading and decrease in vacuum when it happens the O2 sensor
gets a series of 'lower than average' cycles when the misfire starts and the long 'rich' period is a result of the ECU reacting to that.


I'm not saying I know what your problem is though, just adding some thoughts.

This video worked for me. Quick free and easy fix.