buzz test?

[Okiefromwatonga]

So I just got done replacing the shocks (put some RS5000's on it), the front sway bar end links (moogs) and the valve cover gaskets/glow plugs/under cover harness's and have come to realize that who ever worked on the truck last knew even less about these trucks than I do. Both valve covers were missing their rear most bolts. I was looking at the injectors and noticed a few with metal plates on the heads with a R on it, does this mean that they are re-manufactured? I was reading on here about a BUZZ test and was wondering what this is and is it something I should get done to my rig? If so where does everyone suggest I go to get it done?

[stroken04]

Im not real sure about the R's on the metal plates.

A buzz test is:

The Injector "Buzz" Test can be used to look for a faulty fuel injector. It is best to run this test on a totally cold engine, one that has sat overnight and has not been started.

Initiate the "Buzz" test and then listen carefully to the injectors as the test is completed. First, all 8 injectors will "Buzz" at the same time. Then, the IDM will "Buzz" the injectors in numerical order (1, 2, 3, 4, 5, 6, 7, 8). Remember that cylinders 1-3-5-7 are on the passenger side and 2-4-6-8 are on the drivers side, with cylinders 1 & 2 being at the front of the engine. You should hear a strong "Buzz" bouncing from side to side for all 8 injectors. If one of the injectors doesn't "Buzz", you've found a problem cylinder. It is important to note that when an injector fails to "Buzz" properly, you will still hear the other 7 injectors make a faint buzz...this is a designed function to protect the IDM.

Note: Because the IDM will "buzz" the other 7 injectors faintly during individual cylinder tests, it is possible for the "Buzz" test to report no problems detected. If the "Buzz" test reports no failures, but you don't hear a particular cylinder "Buzz"...more than likely there is a problem with that injector.

It should also be noted that an injector failing a "Buzz" test can have many causes. The injector can be in a failed state (loose armature plate screw, bad solenoid, etc.), the UCV (under valve cover) gasket or harness could be damaged or disconnected, the main engine harness could be damaged or the IDM could be damaged. Further inspection will be necessary to determine the actual problem...but at least you now have a place to start.

I think most places charge around $100 to run this test. However for about $350 you can buy an Auto-Enginuity and do it yourself plus a bunch of other diagnostic tests

[Okiefromwatonga]

thanks for the heads up

[GM Duraturd]

I didnt put the back most valve cover bolts back in my truck either...thats not a big deal. It will make it way easier/faster the next time I remove them.