P0641 after oil pump replacement

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WBH05

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Well ole Murphy's law is having his way with me again. getting a CEL after 1st start and now once up to operating temp and toped off coolant the dang OP gauge is now dropping to zero. Start it up and it'll show psi for about 15-30 sec then drop to zero. Zero valve train noise have no disbelief it's not pumping oil now as I put a meling higher volume pump and meling pickup tube and first start idle psi was about 50. Getting code P0641 and going to start with replacing the OP sending unit in the morning and go from there.

Any other suggestions for you guys would be great.
 

SLCHOE

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Why did you replace the oil pump? They last pretty much forever.

What led you to do that is my question.... what symptoms and/or what codes?

The code you have now is a circuit code meaning it's an electrical fault on one of the two 5V referencre signals the PCM puts out to it's sensors.
 
OP
OP
WBH05

WBH05

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Here's the 1st post I made in which it gives detail, but short story long was having psi issues in the morning. The relief valve in pump had a few buggered up places so think it could have deff been sticking as well as o-ring was dried out on pickup tube.

when the psi would bottom before repair it would gradually drop and if you gave it rpm up to about 1K it would pump about 20psi now it shows 50 for about 15-30 secs and then just goes to dead zero and if I clear code it come back on immediately.

Pasted from my intro post:

Upon the test drive I drove it like I stole it and made the oil psi bottom out at idle and valve train NOT happy. Therefore it's currently sitting in my garage with the oil pan off awaiting me to get home tonight with the correct harmonic balancer puller to finish tearing her down. Already have the pan and pickup tube off and the o-ring was definitely dried up and possible culprit but hoping to find a sticky relief valve in the pump tonight also. I drove it for about a week after buying and every other morning or so would bottom out on oil psi after about 2-3 miles from my house at first stop light and then never give another issue. Before anyone suggests sending unit already attacked it from that end first and confirmed it indeed was losing psi not just the gauge saying so. When it wasn't giving issues engine was Extremely quite for a GM 6.0, ran a compression check before tearing into it and had 170 across all cylinders and inside of engine is immaculate for 175K miles. Hopefully with some TLC she'll be a good one to last me a while!
 
OP
OP
WBH05

WBH05

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So found what appeared to be a broken wire on the OP pigtail so replaced that and viola-NOT , had OP for a few mins and no code till a short test drive and bam zero OP on the gauge and now have P0641 and P0101 Mas Air Flow codes. Clearly the engine has OP since there's no noise in valve train what so ever and clearly my patients are running short now. Only other thing I think of that I did before the initial start after pump was switching out DRL bulbs to amber bulbs.

I have checked the MAF plug and the sensor and they both look fine..

Once it's at operating temp you can shut if off and start it back and gauge will jump to 50psi for about 3-5 secs then just fall out to zero.....Stepper motor maybe??? All other gauges work fine though.
 
OP
OP
WBH05

WBH05

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Last update to this thread I hope! Found wire broken inside the insulation at OP sensor and apparently shorted out the almost new sensor as well. replaced the pigtail and sensor and Now has 50psi idling and gradually climbs to about 70 at 70mph. So end job was oil pump, pickup tube, sensor and sensor plug along with belts hoses differential flush etc etc. Should be good for another 100k now to address the blown air shocks on the rear I noticed while replacing the Evap solenoid.
 

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