Fuel Knock?

[HammerDown]

What is it what, causes it, could it be timing related and does it come and go? Also how does one diagnose it?

 

[bigpanda16]

Spray some wd40 into your turbo or intake manifold and you should hear it. Slobbering injectors putting fuel into the cylinders at the wrong time

 

[icanfixall]

A fuel knock is an injecter with a very weak spring allowing the fuel to spray in very early in the compression stroke. Sometimes a leaking injecter will cause it but remember once the injection pump has charged a cylinder thru the hard lines it cuts off any additional pressure buildup in that line. It can stil leak in but not flow uncontrollably. Crack open each injecter and listen for the noise to go away or change dramatically.

 

[HammerDown]

Question, will the knock come and go?
I would think a "weak injector spring" would always be weak thus always knock...correct?
Or, could fuel-knock be from a sticky injector piston?
Being "fuel related"...will it cause smoke out the tailpipe which I'm not seeing.
Thanks