I have a 2001 Blazer 4x4. Lately I have noticed a ticking noise in my engine compartment. Upon investigating it seems that the noise is coming from the central port injector assembly. If I put a screwdriver to the black part where the wires hook up and the other end to my ear I can hear the noise. It goes away when I snap the throttle and it comes back just before it goes to idle rpm. Cruising at highway speeds I cannot hear it. Anyone out there have or have had the same problem?

 

Haven't heard it on mine, but a '92 Dodge Dakota I had made the noise from the injectors and it was considered normal.

 

Sounds like what is going on with my 1998. May be a fuel-related. Mine is throwing the MAP sensor code and acts like it wants to die when it's idling, but happens on rare occasion. But the tick has been going on for a few days now. As I said, may be a fuel-related problem. That's all I can think of.

 

Possibly the EVAP purge solenoid? It's controlled by the PCM and operates on a duty cycle so it normally "ticks" when its commanded to operate. It's on the passenger side of the intake plenum, just rear of the ignition coil and ignition control module, two small wires going to it.