Perplexed
 

I've been a mechanic for many years. Recently I went through a change of life, went from living comfortable to just getting by. So now money's tight. I found a deal of a life time recently. I found a 99 f-150 with 136000 on the clock, beautiful truck inside and out. The lady said it was running rough, and immediately I though vacuum leak, which it turned out to be. After fixing that and installing a new fuel pump, I'm still under 600.00 on my investment. Here's the problem and it doesn't do this all the time, one day it might knock by the next it won't. I've scanned it, no codes! I'm baffled, any and all help would be great. Thank you

A bad Engine Knock Sensor?

Sorry to hear about your situation.I'm in the same boat.After 30 years working as a pipefitter/welder I have been disabled almost a year now.

Is the knock like a "bearing" knock,as if it is not getting enough oil,or a "pinging" like knock,upon acceleration?