Trying to chase down a rough idle on SOHC after replacing most related sensors. Idle fine, then PCM sets code and idle goes to ****.

[Justin_]

Your timing is probably off from guide wear. Both banks have lower than normal 4.0 sohc compression so it more than likely valve timing.

Well, only hoping to get 6 months off it. I did recently replace the tensioners with OEM Ford ones recently.

I have the timing tool and could try to time it, but I don't want to make it worse. Can definitely make it down and pull the valve covers off. If I take my time what do you think my chances are of actually making it better?

I am kinda worried about it with how big if a deal everybody makes it.

 

[boominXplorer]

If both banks are off then it is more than likely your main tensioner has failed. It is under the timing cover behing the water pump. I don't recommend replacing the individual bank tensioners without pulling the valve covers so you can make sure to keep tension on the guide/chain. If a guide is partially broken it can fall as soon as you pull out the tensioner and you've done more damage just trying to be preventive.

 

[Justin_]

If both banks are off then it is more than likely your main tensioner has failed. It is under the timing cover behing the water pump. I don't recommend replacing the individual bank tensioners without pulling the valve covers so you can make sure to keep tension on the guide/chain. If a guide is partially broken it can fall as soon as you pull out the tensioner and you've done more damage just trying to be preventive.

I can definitely believe that.

Anyway to check the jackshaft tensioner without pulling apart the entire front of the engine?

I guess I could probably pull a valve cover then move the crankshaft and see how much slop I get.

At this point I have seen the top of both chain guides and from there they look okay, but can't say anything about the bottom.

 

[Justin_]

Well the other day I was looking under the truck and found that my one-year-old muffler had nearly completely broken in half.

So that is probably what was "getting worse" about it. New muffler on and it's so much quieter. I can hear new sounds from around the engine that I will look into.

AutoZone's BR exhaust is complete garbage.

I'm also realizing I need to do something with the rear springs. I have some coilovers I ordered so I'll probably start with seeing what those will do but long-term that definitely needs replaced. I REALLY don't think it should be flat, especially with just day to day weight in it.

 

[Exploder321]

Check the connectors to the Fuel Vapor Management Valve, they may be broken or have bad o-rings undermining the fuel vapor management system. On the 01 explorer, one is green, the other white.