I have a 1997 ram 1500 sport with a 5.9 magnum. I just rebuilt the motor.. we’ll not just as it has about 10k on it now. It ran like a top for the first 1500 roughly, but then slowly some issues started to pop up. Upstream o2 first (mind you the ecm had no signal from the o2 sensor for over 5 years as wires were ripped out of the sensor and my dad previous owner never replaced it) then tbps code popped, so I replaced it. Cmp, ckp, coil, cap, rotor, plugs and wires next after codes relating to them surfaced. The upstream failed about 3 weeks ago so I replaced it, now if I try to get into the rpm’s at all I break up really bad above 2,500. As of lately the truck will just die. It will idle just fine sometimes, other times it’ll die after just a few minutes if that. I will have to unplug the ecm and coil at times and let it sit for a few minutes. No power to save my life since the breaking up started happening, tonight as I was leaving work it died. Had to unplug the coils and ecm, I’m getting plenty of fuel but no spark. Everything revolving around spark is replaced and I have good power and connections across the board. I haven’t replaced my map or iac yet as I don’t seem them causing this issue. I’m thinking bad ecm as it has 290,000 on the module itself. Any help would be appreciated as it is my daily driver and I enjoy my truck.

 

Did you replace the crank sensor with a Mopar cranks sensor? I had very similar issues as your symptoms and replaced my aftermarket (Borg-Warner) crank sensor with a Mopar unit. The random loss of spark issue went away afterwards.

If you do truly suspect a PCM issue, it is a good idea to keep a spare unit around. A 1997 PCM with the same part number as yours will swap out with no issues - they're plug and play.. I keep a couple of used PCMs around just in case for my 1996 Dodge Ram.

 

Just a duralast part from autozone, as I work there. So in that case no, it worked fine in the beginning. I can always run to the dealership and get a quote on what. On a side note before I replaced it I would have to turn the key twice and let the pump prime twice to start up.

 

Get the crank sensor part number from the dealer and check online or download the parts manual for your year and find the part number there - https://dodgeforum.com/forum/2nd-gen...s-manuals.html. You can typically find a Mopar crank sensor via the web cheaper than the dealership. You can also check rockauto.com with the Mopar part number to see how much they sell it for as they sell dealer parts, too.

 

Mopar crank sensor is on back order and they don't know when it will be available. At least that's what i was told from MoparPartsGiant.com a few weeks ago.

How did you determine this? Fuel pressure will jump right up to 49 psi with one turn of the ignition with a good fuel pump. Did you happen to test pressure? Same with spark, Did you put a timing light on the coil wire to see if and when it's firing? And I'm just curious if you set the fuel sync after the rebuild?
When you "rebuilt" the motor did you do the plenum fix?

 

When I rebuilt the motor I had one of my colleagues swing by and we did get the fuel synced as far as I know. He knows a lot about the moose small block family motors and the trucks basically inside and out for the years they were offered. I unfortunately have no way to test my fuel pressure as the rail that’s on my truck doesn’t have the nipple to test it. When the truck dies you can smell plenty of fuel. Kinda smells as if it has overloaded itself but didn’t at the same time.