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I feel your pain! I had a slight misfire that wouldnt throw a code for a month. I had the truck to the shop several times. I had leak, smoke tests and a bunch Maf cleanings, seafoam , plugs etc. I kept telling my mechanic i thought it was the intake gaskets and he wouldnt listen. Aftet i got pissed and told him to do leak test and smoke test again. He soaked my motor which caused the knock sensor bowls to fill with water. Then my truck went from a slight misfire to limp mode. So i replaced the knock sensors and harness. Got steel fel pro gaskets for the intake. It wasnt a bad job. Next time i would definately remove the hood. But misfire gone and so is my mechanic.
Wow! I think I’ll have to do the gaskets too.
Should I just replace knock sensors at the same time? Are they hard to replace?
If you are pulling the intake off, yes go ahead and replace the knock sensors while you have it off. Very easy to replace once the intake is off.... ONLY use ACDelco knock sensors.
Picture from when I did mine. I went ahead and did the valve cover gaskets too since I was already going all in there. Obviously I also cleaned and painted them red too...
The knock sensors are in the middle with red high temp RTV sealant around the rubber plugs. Once you pry the big rubber plugs out, you squeeze the sides of a connector on the wire and then just use a socket to remove them. You can also see that I cut some foam blocks out of some randor foam packing material I have laying around to plug the intake ports in the heads while I was working to make sure that no debris or anything falls into one. There were even rocks under the intake on mine along with dirt, leaves, etc. I have no clue how a few little rocks can end up there. lol
You can just see them but at the very back towards the firewall end is the oil pressure sensor and camshaft position sensors. If you ever have to replace one of those, that is where they are.
I am in the process of doing mine, New Knock Sensors, Intake gaskets, O2 Sensors and spark plugs (Irodiums) and MagnaFlow dumped before axle. that will be my ECU/Engine tune up, My fuel mileage had gone from 13 to 9.8 before starting so want to see how all this affects that.
Originally Posted by robthomas16
Wow! I think I’ll have to do the gaskets too.
Should I just replace knock sensors at the same time? Are they hard to replace?
Yup, that is about how mine looked too. lol A surprising amount of stuff somehow makes it under there. Careful to not let any fall down into the heads although it would probably just sit on top of a valve and you could vacuum it back out with a small nozzle. Obviously the pic I showed was after cleaning things up.... yours looks like a later one since it has that additional tube coming off the one rocker cover.
Should I just replace knock sensors at the same time? Are they hard to replace?
The knock sensors are working. The source is most commonly caused by carbon deposits on the valves.
Start with an induction service and only use top tier fuel.
I am in the process of doing mine, New Knock Sensors, Intake gaskets, O2 Sensors and spark plugs (Irodiums) and MagnaFlow dumped before axle. that will be my ECU/Engine tune up, My fuel mileage had gone from 13 to 9.8 before starting so want to see how all this affects that.
What a mess.. Take your time cleaning/removing all the carbon deposits. After you are done and start the engine, send some seafoam down the throttle body, then after the smoke clears, change the oil.
Also change the knock sensor wiring harness (Ac delco) they are prone to issues. I also built little u shaped dams around the knock sensors out of silicone just to divert the water around them. I left the back of the sensors open so that if water did get in there it would run out the back instead of sitting there and leaking down into the sensor bowls. Also siliconed the hell out of sensor caps and the hole the wiring harness goes through.
