Fuel trims negative at idle and decel

Hi, I'm Joshua, and I'm a parts changer. I'm new to GM, Diag, and this forum so please be nice. 

I was recently gifted a 2005 cadillac escalade ESV. 348,000 miles.

It was last driven by the previous owners son then sat in the driveway for 2 years. 

Started with incredible misfires. 
parts changed include
Plugs, wires, injectors(cheap AM), battery, fuel pump, most(if not all) vacuum lines, intake manifold gasket, bank 2 cat, bank to up and downstream O2 sensors(bosch), radiator and half the hoses. MAF sensors, air filter etc.

Drove it 4000miles from NC to AZ and back. Running rich (P0172, P0175) Then had a cyl 5 miss(P0305). Switched plug, wire, and coil to no effect. Put one of the functioning old injectors back in and it stopped.

2 months later 

Still Have negative fuel trims long1 -10, long2 -18 at idle. Goes to zero during acceleration comes back negative on decel. 

That's a lot and tons of it could be irrelevant. It's a start tho. 
 

JBRal wrote:

Still Have negative fuel trims long1 -10, long2 -18 at idle. Goes to zero during acceleration comes back negative on decel. 


 

Long Term Fuel trim is only part of the Big Picture. What is your TOTAL Fuel Trim? ...  Total Trim = Long Term + Short Term...
What kind of activity is happening on the O2 sensors, during the same time.

Is the car hard to start in the morning?

@Chad : I genuinely don't know how to answer that. The short trims dance around usually between 0 and -3.1 but sometimes they are bouncing around from +4.9 to -7.8 and everything between.

Same with upstream O2. .115 to .885 V and everything between.

Not hard to start but she starts hard. If that makes any since. Again, this is my first GM so that could be normal. Like, revs to 2000 and take a few seconds to settle back to 560ish