Knock Sensor Fix #2
 

About two years ago i changed my knock sensors for the first time. This spring the codes came back and after all summer i finally got around to replacing them again. I got a set of the fel-pro metal intake gaskets, ac delco Gm knock sensors, and the dorman harness. I did the job without reading the instructions on the gaskets and figured that they would bolt under the headstuds, as they only had two loops for attachment and they lined right up with the studs. The instructions for the gaskets say to sit the loops on top of the studs, not bolt them down with the studs (didnt read instructions so i missed this part). Also at the end of the job i was reinstalling the egr on top of the intake and realized that it was loose and i could easily wobble it around with my hand. Anyways i started the truck and got a loud knock for about 10sec and then it disappeared (figured everything just had to get back synchronized). Within 10min of the first drive the codes for both sensors came back and i also got a system lean code. I reset the computer and re torqued the intake and also put some washers under the egr bolt so that it would hold it firmly in place. Now going on two days the codes havent came back and the truck seems to be running great. All except for when it is warm started. The truck will idle at about 500rpm and have a rough idle making the whole truck shake around like its cammed. The truck is not cammed so this is a problem. Please let me know what you think is the problem here, i really dont want to tear the intake off again just to put the gaskets where they belong (everything looks to be sealing properly and is lined up good).

Is it possible that something fell down into one of your intake ports?

I think a little bit of dirt got in the #2 hole. Also the codes came back today while on the highway p0327 and p0332. No system lean code has returned at this point. Also the pcv valve may be allowing a little air on the side of the intake, as I couldn't get it to go back in flush

Well I opened up the main harness of the truck right where the wires for the knock sensor connection are and I went about 8 inches further in the harness. The wires inside the main bundle and fine but the ones that come out for the connection and a little brittle so I retaped those and just let it be. I also found out that the rough idle happens only after the engine has got to operating temp and cools off and gets restarted. Again the truck is running surprisingly well for the symptoms it is having