I have a 2002 Cadillac Deville, I am having problems with 2 of my injectors not working, already tested the injectors with a meter and they read 14.4, then I unplugged the 2 injectors and there was no change in engine performance, used a stethoscope and checked injectors and don't hear anything when I check the #3 and #8 injectors, but all the rest where fine, what could be wrong?

 

Where is the fuel injector located and how hard is it to replace,2002 Cadillac Deville?
please share with me if you have idea.

Thanks. .......