JasonG

I’ve got a p0171 and p0300 happening and can’t for the life of me figure out why!!
What I’ve done
I’ve checked wiring integrity
Powers and grounds
I’ve induced rich and lean conditions where the 02s react accordingly
Smoke test for vacuum leaks
Relative compression=pass
Changed b1s1 02 =still getting system to lean +33 long term fuel trims bank one
The misfire happens on bank 2 after the pcm cuts power to the b2s1/b2s2 power so they sit at 0 Volts on the signal return!!
Next weird thing is the iat has zero volts on the day pid but there is infact voltage present 3.3v to be exact!! And when unplugged no mil light thrown No codes other then the previously mentioned ones
Also when all this starts happening after reaching operating temp the PW to #injector goes from 2000+/- to 300u and all the rest stay up in the 2k range

I’m leaning towards pcm to my knowledge all
Of the above mentioned is controlled via pcm

Any and all help would be most appreciated

Here’s a shot of injector pulse width at 300 after the issue starts after 10 min or so

Here is the shot of the bank 2 02 reporting zero info after 10 minutes of running fine and working fine

RacerHog

I dont think you have an Injector issue at this point.... They just dont know what the 02's are signaling back to the PCM... So they are all just shooting at the stars...
Chase the fix for the 02 sensors.... Also Make sure the air intake is sealed and all the sensors are in place... Recheck and or smoke test for a leaks on the intake side.
P0300 is just cause your chasing the problem i think....
May have to use Alldata of ProDemand to chase down the wiring back to the PCM.... If that call checks out good.... Then I would go with the PCM...
Just my 2 sense.... Cheers
Keep us posted

JasonG

Thats as far as I’ve gone I’ve checked wiring integrity and circuitry

the weird part is it’s intermittent!! All the 02s read and react fine when first gone into closed loop then after about 5-10 minutes of idling it’ll just cut power to the b2 pre and post cat 02sensors they work fine for a bit then just like a switch they have no signal being sent to the pcm. After the 02s cut out the misfire starts so I’m not worried so much about he misfire as I am to why the power is not being sent back to the pcm on the signal side of things!! I’ve exhausted all my smarts on this one and would really appreciate any and all help before pulling trigger on pcm

RacerHog

I Agree....
However, if the 02 still has it's reference voltage? at the time it acts up? But not coming back to the PCM with live data? I would replace the 02's sensor before I did the PCM as well.. Only because those are cheaper and less likely to fault out. But definitely check for bad connections at the connectors!!!
Thats about all i got for you... Cheers

Keep us posted...

JasonG

According to data there’s a 2.5 reference volt there but should be 5 volts if I remember correctly or closer to 5 that’s what they read ignition on engine off anyway is 4.99volts and are 02s known for heating up and stop reporting like a switch turn them off? I mean anything is possible I guess

RacerHog

5 Volts is correct as far as I know..... Unplug it and see if the Reference Voltage comes back when it happens? If it does not come back, I think you can point at the PCM Driver...

Also, Check and make sure the PCM is for that vehicle. Check the Software as well... Unless you know it is correct... Maybe look for water damage within the PCM or the green fuzzy stuff in the connector?

JasonG

Connector looked perfect and clean
I didn’t do any tension test on the pins but no codes given how sensitive these systems are I would assume there’s no issues there!! PCM looks relatively new for 280k so could be the wrong one but I’d imagine there’d be more happening if it didn’t belong. Maybe software issue