Rough Idle - Loping Then Died?

[Scrat0351]

Hey guys, I have a 2018 RAM 3500 (Aisin) DRW with 150k miles.

It is DRD tuned with a 5" turbo back exhaust; the FASS lift pump changed filters 3k miles ago.

Everything else is in stock.

I was driving the other day at a red light when it started idling rough and shaking and loping or missing.

I didn't notice any smoke but didn't get out to look.

I turned around to return home, and about 5 min later, at a red light, it died and never started back.

I had it towed to my house, and it isn't throwing any codes on the MM3.

I changed the crankcase position sensor, but it still won't start.

I have no idea where or what to check.

No codes to go off of, and it won't start.

Before this happened it has been running fine.

The only issue I've been having is the service electronic braking system coming on and off while driving.

It comes up, then goes away, and does it repeatedly while driving.

Any help or advice would be much appreciated.

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[AK Bob]

Hey guys, I have a 2018 RAM 3500 with 150k miles.

It is DRD tuned with a 5" turbo back exhaust; the FASS lift pump changed filters 3k miles ago.

Everything else is in stock.

I was driving the other day at a red light when it started idling rough and shaking and loping or missing.

I didn't notice any smoke but didn't get out to look.

I turned around to return home, and about 5 min later, at a red light, it died and never started back.

I had it towed to my house, and it isn't throwing any codes on the MM3.

I changed the crankcase position sensor, but it still won't start.

I have no idea where or what to check.

No codes to go off of, and it won't start.

Before this happened it has been running fine.

The only issue I've been having is the service electronic braking system coming on and off while driving.

It comes up, then goes away, and does it repeatedly while driving.

Any help or advice would be much appreciated.

Does it crank (does the engine turn over)?

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[AK Bob]

If the engine cranks, select the fuel rail pressure actual and desired PIDs and post back the pressures while cranking.

You need over 4,000 psi actual to start and idle.

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[Corkey]

How long ago did you change the fuel filter?

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[Scrat0351]

Yes it turns over but doesn't even act like it might start.

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[Scrat0351]

I looked at desired and actual, and they were over 4k.

It fluctuated between 4300 and 4800 mostly.

Fuel filters were changed about three months ago with the oil.

They have a little over 3k miles on them.

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[Scrat0351]

3 months, a little over 3k miles ago.

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[AK Bob]

I looked at desired and actual, and they were over 4k.

It fluctuated between 4300 and 4800 mostly.

Fuel filters were changed about three months ago with the oil.

They have a little over 3k miles on them.

So far, fuel pressure doesn’t seem to be the issue.

You may have a bad Crankshaft Position Sensor.

Try monitoring your RPM PID while cranking; it should show between 150 and 200 RPM while cranking.

See the attached information with no start symptoms and testing strategies.

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[Scrat0351]

So far, fuel pressure doesn't seem to be the issue.

You may have a bad Crankshaft Position Sensor.

Try monitoring your RPM PID while cranking; it should show between 150 and 200 RPM while cranking.

See the attached information with no start symptoms and testing strategies.

Thanks for the information.

I have been at work the last few days, so I haven't been able to try anything until today.

Rail pressure is around 4800 with a max at 6k.

RPMs are right around 175.

I did change the crankshaft position sensor, but nothing changed.

It has been in the low 70s and upper 60s here, but when I crank it, it keeps going into diesel preheat.

I don't think it used to do that unless it was below 50's or 40's.

I also removed fuel filters and emptied them.

There doesn't appear to be any water, but the water filter is pretty heavy, so I ordered some new ones.

I kept the same filters until new ones came in and primed it.

The pump seems to be running longer than usual before cranking.

I will start going down the list you sent (much appreciated) and keep you updated.

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[Corkey]

https://fassride.com/3-signs-time-ne...l-fuel-filter/

Pretty good article to read.

It might help out with troubleshooting.

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