Newb troubleshooting intermittent ping

[AlaskanRider]

Hey there,
Im new to this forum, but I really like it, its been a great resource. Hoping for some help with my problem, which i've been trouble shooting and am totally stumped on. The truck is a 91 ranger 2.3 rwd with 128k on it. I bought it at 120k, and supposedly the motor had been rebuilt with new bearings and rings by the guy who sold it to me. The motor was real clean, and looked like it had been pulled.

Im getting an intermittent ping, sometimes its really loud, like a giant spray can rattling under my hood, but most times it's nonexistent. Its loudest around 3/4 throttle, quieting down if i floor it. It stops entirely if i drop the gas, and it doesnt do it if i downshift to slow down.

It always starts easy and runs as strong as id expect a 2.3l, it also idles real smooth. I get an intermittent CEL with a code 41, although it doesn't ever ping when the CEL is illuminated. The guy i bought it from seemed to think that the CEL was cause by the exhaust, which is a straightpipe with a cat welded into it. I haven't seen him in about a year though, and the ping has started since then.

I checked my egr, and it seems to be working. I cleaned my maf, which seemed to make the truck slightly more responsive (maybe) although it has pinged pretty loud since then. My vacuum lines seem to be in good shape.

I am stumped, what could possibly cause a ping to come and go???

The truck has always been at operating temperature when for a while when it pings, but somedays i can drive it for 2-3 hours hard and it wont ping at all.

It never diesels, plugs look good, wires are new.

Ideas anyone?

 

[AlaskanRider]

Oh! Im also getting oil spitting out of the valve cover, which pools in the throttlebody. It also comes out of the dipstick tube, so i think theres some pretty serious blowby. Im willing to replace the rings/and or pistons, but i want to get this ping sorted first.

I also found service bulletin no. 91-20-11, which says if you get a MIL with no fault present and a continuous memory service code number 41, that you should replace the EEC-IV processor.

Mine has a code 41 KOEO and nothing else just like the bulletin says, so i guess that i will try to find a new eeciv processor.

Otherwise i might need to shoot this truck with a bazooka.

 

[AlaskanRider]

bump,
I just tested fuel pressure, 39 psi at idle, barely moves when i blip the throttle.

Still looking on ebay for an ecm, although i might have a lead on one, double check part numbers later.

Any other ideas?