I have a 1998 Dodge Ram 1500 with the 5.2-liter engine. Starting at 18,000 miles it began pinging and has failed to be cured. I have been through 3 brands of fuel and all the grades. I take it in for service at a Dodge dealer but they have been unable to figure out what is causing the problem, or how to cure it.
They have so far replaced the intake plenum gasket, intake manifold gasket, flushed the fuel injectors and serviced the throttle body. The truck now has 45,000 miles and is still pinging. Can you think of any cure for this chronic condition which the Dodge dealer is unaware of.
I have a couple of suggestions not on your list of work performed, but the Dodge dealer certainly should have been aware of these issues.
First on your list, and a common failure which can cause a spark knock on several Dodge engines, is an internal vacuum leak at the intake manifold plenum gasket, which hopefully was replaced correctly.
Next time you visit the service department, ask them to pull up Technical Service Bulletin number 18-48-98. This one deals with another common cause of a misfire and/or spark knock on multiple engines, including the 5.2-liter, and involves rerouting the ignition wires as a fix.
And last, but not least, TSB # 18-05-00G tells us about a software recalibration which is to be installed to eliminate the spark knock when all else fails. Be absolutely sure that all of the above have been completed before going any further.
Also keep in mind that high engine coolant temperatures can also induce a spark knock, and long-term knocking can cause internal engine damage. Improper combustion eats away at pistons.