3.0 rough idle and missfire

[clayborne]

So if the issue is the recessed valve seats per TSB 05-26-3, is there anything a macine shop can do about that? Or would we need new heads with hardened valve seats? I don't think I understand well enough what the valve seat looks like to tell - is it just a part of the same iron casting but with some form of surface hardening?

I may be getting ahead of myself since we don't know that's the issue in either of our cases, but just trying to understand better how things work.

A reputable machine shop can remove the old valve seats and put in better ones. The only reason I could see not going this route is because of the time it would take to remove the heads find a shop and wait a while before they repair yours (the one local to me has a 4-week lead time). The benefit of having new heads is that you can swap right away. That too has its drawbacks If they are new there are possible casting issues and if they are rebuilt originals you might wind up in the same place years down the road.

Of course this isn’t knowledge from my Ranger but from previous head issues from various previous cars. I am assuming there is nothing about the 3.0 heads that make them special in any way so this should be accurate.

 

[Dave18]

Okay well I know this isn't my thread but I finally had time to replace the injectors and didn't see any improvement... I've replaced spark plugs, wires, coilpack, fuel filter and fuel injectors, so I'm now assuming my misfire is a compression issue. I think my next step will be to take the truck to a shop and have them do some testing to determine whether the leak is from the valves or the rings (suspecting the exhaust valve(s) because of the TSB), to make sure the block is worth buying new heads for. Does this make sense?

I'm hoping from a dry+wet running compression test we could at least get an idea of how much is leaking through the heads (valves) vs. the piston rings... is there any other test that would be worth asking for? It's possible to view the state of the cylinder walls with some kind of scope, isn't it? Thanks everyone!

 

[superj]

vacuum test can tell a few things too. i imagine between a compression test and vacuum check, it should tell you whats wrong.

 

[WutUp Clegg]

Okay well I know this isn't my thread but I finally had time to replace the injectors and didn't see any improvement... I've replaced spark plugs, wires, coilpack, fuel filter and fuel injectors, so I'm now assuming my misfire is a compression issue. I think my next step will be to take the truck to a shop and have them do some testing to determine whether the leak is from the valves or the rings (suspecting the exhaust valve(s) because of the TSB), to make sure the block is worth buying new heads for. Does this make sense?

I'm hoping from a dry+wet running compression test we could at least get an idea of how much is leaking through the heads (valves) vs. the piston rings... is there any other test that would be worth asking for? It's possible to view the state of the cylinder walls with some kind of scope, isn't it? Thanks everyone!

I have one of these and I tried looking at my cylinder walls with it. Worked great. I found scratches in one cylinder.

Milwaukee M12 12V Lithium-Ion Cordless M-SPECTOR 360-Degree 4 ft. Inspection Camera Kit 2323-21 - The Home Depot

 

[bcstoy]

This problem seems to be like mine. I am waiting to get a re-flashed computer. I have better compression. Also I discovered today the previous owner had installed 3 different tires sizes 225/75/15 at the front, 215/75/15 rear driver side and 225/70/15 rear passenger side. I recall seeing p505 in the permanent memory also. I suspect that creates problem for the PCM when shifting gears and determining the right vehicle speed.