Can the fuel sync being far enough out ('96 Ram 5.2/manual tranny) of setting that it could cause partial throttle ping, whilst still allowing easy startup n run?

 

No. If it runs fine otherwise it's not the fuel sync.

 

Probably blown plenum. Or maybe low fuel pressure, Or bad O2 sensors.......

 

The plenum gasket has been replaced (hughes mod), oil catch can on PCV with no visible oil ooze into intake anymore. New valve stem seals n she burns very little oil. All TSBs related to partial throttle ping done MINUS death flash on PCM. The partial throttle ping started when I dumped the cat after the innards broke up. Fuel pressure maintaining ~50psi, even under moderate load. All cylinders checked out amazingly clean with borescope...typical carbon buildup for an engine with 237K miles. Compression before oil between 135-150 psi on all cylinders, 150-165 psi with oil n less than 20% on bleed down (all cylinders). I've tried hi octane gas, techron auplenty, etc, with no relief. Engine runs great n no overheat, even better power under heavy acceleration since loss of cat. Short n long term fuel trims average approx +3~9 long term, roughly the same for short term (steady load, RPM and level road conditions). I'm guessin' the O2s are okay?!? (Denso). Intake temps always acceptable. Better since oil catch can install. 180 degree thermostat, with a 20 psi radiator cap. Could the lack of back pressure from the cat or maybe the downstream O2 sensor not getting the info the ECMs lookin' for MAYBE cause this? Don't wanna replace the cat if I don't have a reasonable expectation of a fix, cause I'm tryin to keep ol blue goin 'without big money flowing into repair. Any ideas or just live with it?

 

I don't think the cat will make any difference at all. Wouldn't hurt to have fuel sync checked, it does have a very narrow range of acceptable values....

What spark plugs are in it?

 

Autolite 3923s. Lookin' for someone that'll even do fuel sync anymore round here. Can't get my hands on a bi-directional scanner without big bucks investment...waaahhh! Happy Thanksgiving all!

 

I've lived with ping for twenty years and found what works for me. You stated that after gutting the cat it started. There you go. Get a hiflow magnaflow. Also ditch the colder autocrap plugs and use stock champions rc12yc gapped at .035. Work great for me but my year is .040. Run two seafoam treatments through the brake booster also. If the sensors are old get new NTK from rockauto. Should fix it.

 

thnx ramman, I'll give 'er a try. I still have my old champions...well, a few thousand miles old anyhow!