Calling all 2.9 gurus! 88 ranger idle fluctuation

[88ranger91]

Last night I took the upper intake off, replaced the plugs (all were BLACK), wires, cap, rotor, cleaned the IAC, intake temp sensor, intake, throttle body, checked for vacuum leaks and assembled it all with new gaskets.

Still idles rough jumping between about 900-1400. Still throwing the 41 running lean code.


I have a new motor waiting to be built and put in but want to get this one running ok first. I have a new o2 sensor, map sensor, intake temp sensor, coolant temp sensor, coil, IAC and TPS on order any other ideas on what to replace??? Thanks!

 

[Pauls 4x4]

Check the exhaust. If its leaking air the 02 sees lean and dumps in gas (black plugs... Are they wet?). Or if they are wet, oilly than the 02 tries to lean the mix and throws out warnings from other sensors saying they aren't giving enough gas for what they read. That would be valve seals/ rings. Check your vacuum or compression?

 

[Pauls 4x4]

Also, timing set?

 

[88ranger91]

No exhaust leaks, one plug was wet around the threads. That plug was finger loose and the wet smelled like gas not oil.

Timing has not yet been set as I'm unfamiliar with this type of distributor. I will read up on the process. Thanks!

 

[Pauls 4x4]

one plug was wet around the threads. That plug was finger loose and the wet smelled like gas not oil.!

That's a bad sign. Did it stay tight once torqued?

The 02 reads lean with misfires because it doesn't see the un-fired charge quite right. I'd comp test that cylinder, check the wire... bad exhausts valves/ cracks tend to give me that. Check the injector, etc.
These ol' birds require a lot of detective work OBD2 doesn't!

Sounds like that cylinder is where it boils down to if it's got a wet plug. And if not, you have a second issue

How's the pressure feel out of the tailpipe? Any pops or suction?