Hi ya'll,

I have an issue with my truck. Wanted to pick some brains. I have a 97 Ram 1500 4x4 5.9 automatic. (Came factory with a 5.2) I've done tons of work to this truck. It's a very strong running motor. (Yes, I've replaced the plenum gasket when we swapped to the new heads on the new motor about 8 months ago.)

When my truck reaches stock operating temp, and I accelerate over 1500 rpms....I'll begin to hear a metallic pinging. Immediately after the pinging begins, the exhaust changes tone, the rpms surge and buck, and she stalls out. I'll pull over, put it in park, and she fires right back up, no hesitation. At operating temp, she'll run normal as long as I baby the throttle. If I rev the motor in park, she acts great, super responsive. It only happens when in drive, at operating temp, at 1500rpms or more. The only code she's throwing is the TCC solenoid... which has been there for quite some time. No new codes. This happened suddenly, pinging was not an ongoing issue. I can only assume she's leaning out. Other than that, I'm at a loss as to the cause of her running lean. I changed both the primary and secondary O2 sensors today, i'll be dropping the cat for a physical inspection in the morning as well as replacing all the solenoids in the trans. I was just hoping maybe someone has encountered this type of issue before and can point me in the right direction.

 

You may want to check and see what the fuel pump is putting out. And running a 5.2 on the 5.9 pcm may clog the cat over time.

 

All this sounds like a damaging Lean condition. If it was carbureted I could help, but I'm not versed in factory EFI's. However, the principles are the same....Air/Fuel Ratio. Something is causing the EFI to not send enough fuel when the engine is under load. I guess the first things I'd look at would be, O2 Sensors, Mass Air Flow Sensor, Manifold Absolute Pressure Sensor, vacuum leaks. After that I'd suspect electronics. When looking for vacuum leaks on carbureted engines I use carburetor cleaner. Spray at areas where leaks could occur. If there is a leak, the engine' RPM will change, probably increase.

 

The 96-97 trucks are a little odd when it comes to the ODB-II implementation but if you have a ODB-II reader with live data look at the O2 sensor data and the fuel trim. If the O2 sensors read low and the fuel trim is way up the PCM is trying to compensate for lean but something else is preventing it. Fuel pressure, intake leaks, faulty MAP sensor as already mentioned. Try to pinpoint the issue before throwing parts at it.