Hey Guys,

Have a 2004 Silverado. LQ4, 799 Heads, 50# Injectors. I have 7 Injectors that look like they've been burned brown, how I picture they should. One spark plug looks completely clean, as if it's never seen fuel or spark in its life. They've been in for 8 competition Truck pulls, or the equivalent of 10-12 1/4 Mile Drags.

Have spark on all 8 Cylinders. Used Noid Light on all 8 Connector, all 8 of them are good. So I put new plugs in the front two holes and swapped both plugs. Now they both look brand new. I've swapped Injector Locations without any luck. Pulled Rocker cover and verified all valves are opening. How could this one plug look spotless after so much run time and the other 7 look so perfect? Any insight or ideas available. Does anyone have a way of testing an injector, and how could I verify that an injector is definitely firing??

 

Stethoscope on the injector with engine running and you should hear it clicking if its working

 

I tried Stethoscoping the injectors and all 8 sound the same. However, I can also stethoscope on the Valve Cover and hear the same noise, so I believe that the sound I am hearing is the valve train clicking, rather than the injectors. If I lift the fuel rail and crank the engine over, will that show whether or not the injectors are firing?

 

Yes you will see them spraying

 

I'm going to pull the fuel rail on my lunch hour then and see if they are spraying. I don't see any other explanation for how 1 plug could be so clean and 7 look run and used after that much time. Rockers are opening correctly, plugs are firing, noid light verifies that the injectors are all getting power and grounded correctly.