5.3L intermittent no power/O2 codes. Oil pressure

[pyrowaves]

HELP 5.3L intermittent no power/O2 codes. Oil pressure

Hey, I'm new to the forums but not to diagnosing vehicles. Usually wiring issues and a lot on Ford.

2003 5.3L Yukon.

Under load and long drives (hour plus) such as going up hill when RPM gets high truck looses all power until engine is restarted.

When this happens it sets codes for all 4 O2 sensor circuits. Restart engine and it works fine until next hill. Once it starts occurring happens more and more frequently.

if you stop when it is happening and give it throttle there is little to no response and if in gear engine will eventually stall. If you don't give it throttle it just stays running poorly.

During the event:

B1S1 reads .010-.020
B1S2 reads .020-.025
B2S1 reads .020-.000
B2S2 reads .000-.020
MAF 1.2-1.6
MAP 12.4-13

One symptoms that seems unrelated, but possible to bring some insight is the oil pressure gauge. the above concern is intermittent, the oil gauge concern is always. Reads maxed out until you bring the RPM up to 4K or more. Then it drops out completely. I've seen the issues with it being stuck and caused by the sensor, but never coming down religiously when you give it throttle.

Almost seems like a VREF is being taken out, but no wiggle testing of circuits or other attempts have made the truck act up. Once after a long drive and multiple events I got it to act up in the driveway with just revving up to over 3K. Almost like a Crank sensor or something is taking down VREF or the PCM is flaking out. Won't have access to wiring diagrams until later this week to even see if this is a possibility.

Looking for ideas other than a PCM issue.. Do the O2 sensors share one circuit?

Thanks,

 

[BubsXL]

Could your power loss be related to having clogged cats? The o2 sensors could be signaling that there is an issue downstream. The long drives could heat up the material in the cats and further exacerbating the clogged issue?

 

[rockenthebowtie]

Plugged cats do sound possible I agree however the low reading indicate lean condition and calling for a rich correction you might want to check fuel system pressure and also spray throttle body cleaner around the base of the upper intake manifold gaskets to see if there's and rpm change when spraying and or look at the 02 sensor reading to see if the voltage jumps up to around 0.8 millivolts if theres a change when spraying replace upper intake manifold gaskets