Engine Knock under acceleration.

[OSUCowboy27]

1990 R-1500 5.7L auto 111000 miles

I have moderate engine knock under full throttle acceleration from a stop and part throttle acceleration at highway speed. Engine has to be warm to knock and timing is 0 TDC. New cap, rotor, wires, pcv valve, air & fuel filters. No codes and higher octane does not seem to help. Stock ASDU eProm. Could it be a vacuum leak, weak injector, EGR valve not opening or carbon deposits in combustion chamber, faulty knock sensor? Any help would be greatly appreciated.

[OSUCowboy27]

I am running Bosch platinums. Could this be the problem? Should I switch back to AC Delco? If so, any thoughts on Rapidfire 1 or CR43TS or the cooler CR42TS?

[infinity89]

I have a 1989 Chevrolet Suburban and it does the same thing but only when in park or neutral or if I am slowing down for a stop light or something of that nature. My dad is a GM Master Mechanic and he told me it coluld 1 of two things.....loose torque converter bolt(flywheel to torque conv.) or it coluld be the crank.... hope this helps.....

[2000CAYukon]

If you access to a scan tool, you should watch the knock count to see if it is incrementing when the engine knocks. If is shows as 0, then the knock sensor may be bad.

You could also plug the vacuum line to the EGR valve to see if the EGR is causing the knock.

//2000CAYukon

[OSUCowboy27]

Well, I changed the plugs last night with NGK UR5's and still had the spark knock or preignition problem. My EGR is opening and closing when I put a vacuum pump to it but haven't tested it going down the road. I am going to take the knock sensor out this weekend and have it tested even thought there aren't any codes. I am also going to add Seafoam to the gas to get rid of carbon build-up.