And now a P0300

HER_CRD · **Posted:** Wed Jun 21, 2017 7:24 pm

So my wife was on her way home last night and experienced an engine shake like never before. Checked codes and see I have a P0300 for random/multiple cylinder misfires. I did some research and see that low fuel rail pressure can cause an issue. I did read pressure on Torque Pro, but I'm not sure what I should have since I couldn't find a spec. Anyone have a spec?

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flash7210 · **Posted:** Wed Jun 21, 2017 8:23 pm

Exact fuel rail pressure varies depening on throttle position, engine load, and ECM tune.

At idle, fuel rail pressure is about 5000psi.

An easy test is to let the engine idle while watching torque pro and wiggling injector connectors, fuel rail pressure sensor, and listening for engine stumbles.

HER_CRD · **Posted:** Wed Jun 21, 2017 8:36 pm

OK, well at idle it's fluctuating between 4600 - 5000 psi.

Couldn't produce any stumbles from wiggling connectors.

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flash7210 · **Posted:** Wed Jun 21, 2017 9:05 pm

Good.
Clear the codes and see if they return.

HER_CRD · **Posted:** Wed Jun 21, 2017 9:43 pm

Will do.

I should also add that the engine did stop while the wife was driving and wouldn't start again until a few minutes had passed. Afterwards it ran fine.

The ECU is currently programmed to factory settings.

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flash7210 · **Posted:** Wed Jun 21, 2017 9:47 pm

As usual, check for air in fuel.
Maybe this is a early sign of a failing crank sensor?

HER_CRD · **Posted:** Wed Jun 21, 2017 9:55 pm

I did bleed filter head out and did get some air.

I had a thought about crank position sensor myself.

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WWDiesel · **Posted:** Thu Jun 22, 2017 10:33 am

Probably your CPS! When mine went bad a few years back, it put me on side of road for a spell and then restarted and ran like nothing had happened. It never did set any DTC's! :shock:

HER_CRD · **Posted:** Thu Jun 22, 2017 10:51 am

OK. I may just go and buy one to swap out. That's interchangeable with the sensor off the Duramax engines, correct?

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papaindigo · **Posted:** Thu Jun 22, 2017 11:49 am

Maybe CPS maybe not. My notes show crank position sensor - 5066882AA or Bosch 0281002434 also apparently Standard Motor Products PC766 or Airtex 5S7000. You can check for a bad CPS by hooking up a volt/ohm meter; applying heat with like a hair dryer; if resistance goes nuts CPS is bad.

I say maybe not because my 05 experienced one episode of violent shaking and barely moving (shut off for a loooong red light and at restart got the shaking). Made it down the road about 1/2 mile to a parking lot; shut down; checked under hood including air in fuel but found nothing; cranked back up and ran just like normal. Never did it again and did not trigger a CEL.

WWDiesel · **Posted:** Thu Jun 22, 2017 3:48 pm

HER_CRD wrote:

OK. I may just go and buy one to swap out. That's interchangeable with the sensor off the Duramax engines, correct?

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I am not aware of a GM number for it, If you find a GM number, please share! :roll:

These are the part numbers I have on file:
Crankshaft Sensor
Mopar-5066882AA
Bosch-0281002434
Autozone-SU8492

Autozone is the least expensive I have found, $50, and when you open the box it will be a Bosch part just like OEM for a lot less money and they have a lifetime warranty! :BANANA:

HER_CRD · **Posted:** Thu Jun 22, 2017 5:56 pm

I may be very wrong about the Duramax part. I remember reading there was another part of two that worked and thought that was one.

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WWDiesel · **Posted:** Thu Jun 22, 2017 9:06 pm

HER_CRD wrote:

I may be very wrong about the Duramax part. I remember reading there was another part of two that worked and thought that was one.

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We have the GM number for the MAP sensor, but I have never seen a GM crossover number for the CPS... :roll:

Would love to have one if someone has it????

And now a P0300

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