Theirons84

New pcv valve had no change.

I listened to the injectors using a screwdriver like suggested. They all sounded pretty much the same. I then pulled the connectors to each one, one at a time. I started at the back. The #4 cylinder caused a slight idle drop. The #3 cylinder caused a significant drop in idle, almost to the point of making the engine quit. The #2 had the same significant drop. The #1 cylinder was much like the #4, with not much change, but still a slight drop.

There are definitely two separate noises coming from the top of the engine. The first is a sensor or vacuum valve called the vacuum switching valve for the AC. It is what is making the hissing sound. if I pull the two vacuum lines from it the hissing stops. I don't know if this is hurting anything or not.

The second sounds like it is coming from the valve train. I used the same screwdriver stethoscope trick and it seems like it is most pronounced coming right from the center of the valve cover around the #2 and #3 cylinders. It sounds almost like something in the valve train is physically hitting the valve cover. The sound does not smooth out with rpm increase as I originally thought. The engine revving simply masks the noise.

I have a hard time believing that that there is a broken component or something badly out of adjustment in the valve train and cam, because it did check good on compression. I didn't do a long leak down test but all the cylinders held 150 psi or better for a couple minutes each so I feel like there are no significant leaks.

Here is a video of my actual truck. This is the noise:


I still need to go back and be absolutely sure I am doing all the correct steps to check the timing with a light. I don't remember hearing the idle drop when jumping the diagnostic pins, and then there is also something in this thread about disconnecting the tps or something to be sure the timing reading is right. I guess I'll look at that.

I guess I will pull the valve cover again and maybe attempt to adjust valves.

I'm getting tired of messing with this thing. I think the worst kind of problem is one that is hard to diagnose and we get to the point that we are just going in circles.

an1176

The hissing or ac idle up shouldn't be doing that. If the ac isn't working pull the vacuum lines and stick a bolt in the vacuum lines to plug them. Did you check your timing chain guide when you pulled valve cover? If not pull valve cover and check the drivers side chain guide. If it's loose it's broke, also look just above that guide and see if you can see where there chain is slapping the side of the head. If all that is good I would adjust valves. It's not hard and there are many videos and write ups about it.

Theirons84

OK sounds like a good plan. I did see a video of a guy explaing the difference between the plastic and metal guides and how to check then existing one. I will look at that. Also found the video about adjusting valves. I'll go ahead and do that too.

Flash319

That does not sound like chain issue. The rockers can hit the cover. I have ground my cover down because of it. The aftermarket gaskets need to much squish to seal.

That sounds like piston issue. Id be pulling the head.

wallytoo

iTrader: (1)

don't give up.

at least you now know the injectors are firing. you stated earlier that you tested them for leaks. what procedure? as described in the FSM?

Theirons84

Broken valve springs. There are at least three that I can see so far. I will just replace them all with new and reset valve clearance. Should fix this crap.

Anybody know the cheapest place to get a set?

Flash319

Wow never heard of that on these engines before. Thanks for replying with a solution to your problem. Check engbldr.com or rockauto.com for springs.