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Oil Pressure Fluctuation

July 14, 2019, 02:00:25 pm

Coming home on a 5-hour drive yesterday.  About hour 4.5, the Check Engine light comes on for maybe 6 seconds.  VMSpc shows a low oil pressure code.  VMSpc shows oil pressure of 29.5 by the time my eyes find it.  The light goes out.  All is good.  I don't know what VMSpc said when the light went on.

Today I ran into town.  No Check Engine light but the VMSpc dropped down to 15 waiting to pull out of fueling station.  Accelerated and it climbs to 37 or so.  It was fluctuating on the way home from 17 to 30.  It mostly stayed in the mid to upper 20's.  Pulling into driveway and parking it hovered around 17.5.

Any thoughts or ideas?  Thank you!

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Re: Oil Pressure Fluctuation

Reply #1 – July 14, 2019, 04:24:14 pm

Bad sender. 

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Re: Oil Pressure Fluctuation

Reply #2 – July 14, 2019, 08:01:11 pm

What is your VMSPC setpoint for low oil pressure?  Cummins went to a high volume low pressure system on the larger engines, I was used to seeing 60 psi on my 8.3, when I drove a 99 320 I was shocked at the lack of oil pressure.  Normal I am told.

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Re: Oil Pressure Fluctuation

Reply #3 – July 14, 2019, 08:25:22 pm

Oil pressure at operating temp will run mid to upper 30s psi while driving, at a stop sign it will drop down into the low 20s.

Look under Advanced on your VMSpc menu, select parameter Editor, scroll down to Oil Pressure.  Low Red should be about 15, low Yellow should be low 20s.

Every engine can be slightly different and there no exact right answer.  If you are driving at steady speed the oil pressure should be steady.  If not you might have any of a number of things going on.  Check with your Cummins service provider.

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Re: Oil Pressure Fluctuation

Reply #4 – July 14, 2019, 08:49:25 pm

Quote from: Caflashbob – July 14, 2019, 04:24:14 pm

Bad sender.

Loose connection on sender...Happened to me

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Re: Oil Pressure Fluctuation

Reply #5 – August 15, 2019, 02:18:24 pm

I had no time to change anything.  3 trips and 2000 miles later and no issues.  The oil pressure drops to 13 to 17 at idle but holds in the high 20's and low/mid 30's when on the road.  I plan to change the senders at a minimum for PM right now.  Thanks for the help.

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