2008 Escalade P0455, P0172 & P0175, pulling my hair out.

[Fless]

Would like to see the freeze frame data if it's available.

 

[93M6Formula]

So that EVAP code hasn't come on for awhile now and I checked the canister and it seems just fine, never had issues filling up.

But this thing is just so hit and miss right now and it's so frustrating. So I replaced the MAF just to see and nothing changed of course. Yesterday morning I started it, and it just ran like garbage right off the bat, chugging and loping like it has a small cam and eventually kind of smoothed out but the FTs were still around -15 for both banks. Went to town, it sat for an hour, did it's typical hard start crap and was just running terrible and no power. Later on in the day, I went and beat on the thing and came back and the FTs were more like -5 and it was running a little better and had power. Still started hard when hot like usual. I seriously have no idea where to go from here, those rich codes are so generic so it could be literally anything, and that's frustrating.

 

[93M6Formula]

These finally popped up again when it was running like trash in the morning.

 

[93M6Formula]

First pic is what it was doing when running terrible. Second is after I went and flogged on it.

 

[Geotrash]

Did you *swap* the O2 sensors or replace them with new? I'm with @Snowbound and suspect either plugged cats or weak O2 sensors.

 

[Doubeleive]

if it were me, I might start taking a hard look at the wiring, grounds, ecm/pcm, fuse box.

 

[B-train]

You me me mentioned the EVAP system. Are you able to see if there is a pressure change in the tank from cold start to hot restart? I had the vent solenoid stick open on my 08 with the 6.2L and hot restarts were sluggish, fuel economy went in the crapper as well. Put on new OEM solenoid and has been good since

Since the motor was in/out, are you sure all the vacuum lines are connected and not cracked or dry rotted?

The only other thing I can think of is maybe the fuel pump and/or the control module is getting flakey. I had a 2009 Denali that started stumbling and almost stalling out in 107F Temps. I filled with cool gas and then got on the highway for air movement and it seems to clear up. Inspection after the trip showed grounding issues at weird places (seats, air compressor). Maybe do a voltage drop test and see if you have a poor ground possibly.

 

[93M6Formula]

Did you *swap* the O2 sensors or replace them with new? I'm with @Snowbound and suspect either plugged cats or weak O2 sensors.

I only swapped the bank 2 sensor 1 O2 but nothing changed and they seem to be reading like they should.

 

[93M6Formula]

if it were me, I might start taking a hard look at the wiring, grounds, ecm/pcm, fuse box.

This is what i'm afraid it's coming down to. Literally nothing about this whole thing makes sense, because besides the fuel trims being all over the place, all other sensors seem to be doing what they're supposed to. Something during the engine swap happened and I have no idea what. With that said, this thing was from chicago before I got it and lived in the salt, I had to replace stupid things like the power steering pump, alternator, starter, accessory bracket, and even the manifolds because of corrosion, so it worries me that some wiring may be bad somewhere but I have no clue what as no codes for any sensor are popping up.

However the other day with that thought in mind, I checked the grounds for the coils and I believe the crank sensor on the lower end of the block, it was clearly corroded and the corrosion went up about 8 inches, so I cut that all out and replaced it, of course nothing changed though... And the grounds on the passenger head are clean also.

 

[93M6Formula]

You me me mentioned the EVAP system. Are you able to see if there is a pressure change in the tank from cold start to hot restart? I had the vent solenoid stick open on my 08 with the 6.2L and hot restarts were sluggish, fuel economy went in the crapper as well. Put on new OEM solenoid and has been good since

Since the motor was in/out, are you sure all the vacuum lines are connected and not cracked or dry rotted?

The only other thing I can think of is maybe the fuel pump and/or the control module is getting flakey. I had a 2009 Denali that started stumbling and almost stalling out in 107F Temps. I filled with cool gas and then got on the highway for air movement and it seems to clear up. Inspection after the trip showed grounding issues at weird places (seats, air compressor). Maybe do a voltage drop test and see if you have a poor ground possibly.

So even though the EVAP code hasn't popped up for awhile, I think I am going to replace it just to eliminate it, its cheap enough at least and i'm running out of things to replace or check.