03 4.7 Ram cuts off with hard acceleration

[Bagpype]

Hello.
New member here. I just bought a 2003 Ram 4.7. It starts up and runs very well. When I push the gas hard, up at 3-4k rpm the engine cuts and does instantly. This happens in park, neutral or under load. Every time. I am lucky enough to have a neighbor with the same generation Ram that runs so here’s what I have swapped so far:
Throttle body and all sensors attached, crankshaft position sensor, mass air flow sensor, fuel pump. Fuel pressure is around 50 psi and stays there when it cuts off. I am thinking of pulling the injectors next and cleaning them in my ultrasonic cleaner. Any suggestions or direction pointing would certainly be helpful and appreciated…

 

[chri5k]

Any stored codes? If not, might try one of the code readers that supports live monitoring to see if you can capture a transient issue when engine cuts out.

 

[Bagpype]

No codes. I have a fancy Autel mp808 scanner. I don’t see anything unusual on the live data.

 

[jws123]

High mileage engine? when is the last time plugs and coils where replaced?.

 

[chri5k]

No codes. I have a fancy Autel mp808 scanner. I don’t see anything unusual on the live data.

So the engine cuts out and the live data just keeps going like nothing happened??

 

[Bagpype]

So the engine cuts out and the live data just keeps going like nothing happened??

Well it all shows N/A once it cuts. Fuel trims are normal, map vacuum is normal, everything is normal up to the point where it’s shutdown.

 

[chri5k]

Does any data stream lead the others in the brief moment right before shutdown occurs? Can your reader do a freeze frame based on a condition? I.e. if fuel trim or pressure drops below X freeze right then?

Trying to see which system might be dropping out first which then causes the engine to stop.

 

[Bagpype]

Does any data stream lead the others in the brief moment right before shutdown occurs? Can your reader do a freeze frame based on a condition? I.e. if fuel trim or pressure drops below X freeze right then?

Trying to see which system might be dropping out first which then causes the engine to stop.

It does. I can record the data and play it back. All is normal till the entire thing just shuts off and says N/A. Might the PCU be shutting off?

 

[chri5k]

It does. I can record the data and play it back. All is normal till the entire thing just shuts off and says N/A. Might the PCU be shutting off?

If every trace just cuts off simultaneously down to the milli-second, I would certainly look at the ECM power supply. Is there a trace for ECM power supply voltage? It should power up when the key is set to run and stay up until the key is set to off. The Autel loosing communication with the ECM is also a telltale.

 

[Bagpype]

If every trace just cuts off simultaneously down to the milli-second, I would certainly look at the ECM power supply. Is there a trace for ECM power supply voltage? It should power up when the key is set to run and stay up until the key is set to off. The Autel loosing communication with the ECM is also a telltale.

I am horrible with diagnosis. Does anyone know which wire going to the pcm is the power supply?

 

[Bagpype]

Solved it. What I did was disconnect the coil and injector on one cylinder at a time and run it. I found one that when unplugged, the engine wouldn’t cut out. So I switched the coils with the adjacent cylinder and it did the same thing. Switched the coil out with a new one and now the trouble has gone away.

 

[chri5k]

Solved it. What I did was disconnect the coil and injector on one cylinder at a time and run it. I found one that when unplugged, the engine wouldn’t cut out. So I switched the coils with the adjacent cylinder and it did the same thing. Switched the coil out with a new one and now the trouble has gone away.

Good job. And who says your terrible with diagnosis?

 

[Bagpype]

False fix apparently. Did it again while driving. I’m giving up on it and selling it for pennies. This is the 2nd ram I’ve had in my life and both have been terrible vehicles. I’m not sure if I blame the brand or the people who didn’t take care of their trucks. Either way, I think I’m going to steer clear of them in the future.

 

[RamDiver]

False fix apparently. Did it again while driving. I’m giving up on it and selling it for pennies. This is the 2nd ram I’ve had in my life and both have been terrible vehicles. I’m not sure if I blame the brand or the people who didn’t take care of their trucks. Either way, I think I’m going to steer clear of them in the future.

You're trying to fix a 21-year-old truck, it may take a few attempts to reach a solution.

While I might agree with avoiding older high-mileage vehicles unless you're looking for a project, my '21 Warlock has been near flawless since I purchased it about 19 months ago.

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