2.3L ('83-'97) Likelihood of a poisoned O2 sensor after very long rich condition? UPDATE: Silicone Poisoning!! BAD SENSOR!

[corerftech]

Frankentruck is definitely running lean.
90 / 2.3/manual trans.

In other threads I covered wiring and MAF issues, FEAD coils, etc that caused very rich operation while a prior owner continued to drive it.One of the leading issues was over fueling. The MAF corrected this (plus other intake tubing issues)
During repairs I used a full cab of brake cleaner (flammable type) and tested for a vacuum leak. Vacuum at idle is 19-20 inches. Drops to zero on throttle and right back to a stable 19-20.

I had mentioned an exhaust pop on startup. Every other start. As well when letting of throttle I get exhaust pops.
Fuel pressure does leak down when pump is not running, from 35 psi on regulator (new). Either injectors leak or the pump has a bad check valve. But while running pressure is at 30-35 at all rpm depending on throttle position.

Driving I have now noticed that is is lacking power (starving) but drives extremely well. I expect more from the engine and at 18-1900 rpm under load it will sputter like it’s starving.

The O2 sensor saw maybe as much as a year of constant abuse with very very rich conditions.

There is an exhaust leak at the down pipe, the ball/socket shows some black soot from the rich running prior. I know it’s there, I will address the exhaust leak this weekend or sooner.


So there are a few ways to make a lean condition and they are (as I understand):

exhaust leak near o2 sensor (I have that) sucking air in on a closed throttle condition after accel. Causes POP

Start up issue on a cold engine generates POP like a lean pop.
Warm engine same thing occurs, but it’s 50/50 change of happening.

Intake leak/vacuum leak- although I have thoroughly vetted all points from the air box to the head intake flange.

loose or cracked head- well compression doesn’t leak down and is 180/175/175/175

Fuel pump misbehaving- I’ll pressure test the pump at the outlet of the fuel filter this weekend and verify it’s up where it should be and that will verify the check valve.

Injectors misbehaving? Possible for sure.

A bad O2 sensor?? Given the long term rich condition (smoke!) that was like an exhaust leak indicator showing every pinhole on the planet!! I’m sure it’s a durajunk chicom unit as that a what has plagued the car until I got it.

Maybe that bit of info will guide some feedback from someone. The fuel economy is awesome! Like amazing——- like maybe I’m so lean I’m going to do damage! It’s keeping me from driving the car on the highway in 5th as that lands squarely at 1800-2000 rpm, spitterville. And if it’s that lean (you can inhale the exhaust for hours and feel just fine- LOL), even though the coolant temp is low I’m afraid of head temps going up and doing damage.
No CEL, ever. I was able to resolve all other running issues.

There is a window I need to jump from and there are several to choose, need to jump from the most likely…

Thanks in advance.

 

[scotts90ranger]

Those O2 sensors aren't too expensive, but if it comes out without too much trouble I would look at it, if there's a bunch of soot you can burn it off some with a propane torch... which is also not a bad time to check the output with a volt meter. The two wires that are different colors (4 wires, two are the same color which is the heater, the other two are the sensor), should be 0-1V depending on heat and a few other things, I forgot what to look for when playing with a torch...

 

[corerftech]

And the O2 sensor wins the event clearly!

Silicone poisoning!

The last owner used Blue "some kind of RTV" on all the intake flanges....... Why cant people just use good old gaskets and 3M Gorilla Snot?? I do... (did) on the thermostat housing and the IAT that I replaced (on the threads a taste).

Ill post pics, laptop feeling lazy about the cloud right now.

Clearly silicone. Matter of fact all the black soot leaks that were present at the headpipe (very light) are now burned off.

The car starts with no pop, at all.
The car when cold runs like its cold.
The car otherwise idles like a friggen baby (it was smooth but now its just a sewing machine), the low end torque is huge (low throttle, putting along at 1100 rpm in second), and that spot from 1700-2000 rpm, gone. In any gear at that rpm, lugging the engine uphill on no throttle, its just puts along. Extraordinary change in behvior. When fully heated its is just quiet and now has manors at low throttle positions.

The only exhaust note it has is the ridiculously short glass pack and turn down gurgling on decel, no BANG and gurgle or even multiple bangs. Or there is nothing but relatively quiet exhaust flow. Omg its awesome. My wife may just drive the car and not be embarrassed.

Forget the injectors and fuel pump....... its off the list. Night and Day change, took all of 10 mins after I found a 7/8 wrench.
And HE--- BUBBA-- didnt really use much torque on the sensor, Im sure it was leaking a bit from the signs on the crush washer.
Ill remedy the easily accessed headpipe and retorque tomorrow on a cool pipe.

$37 buck Walker Fix. Adios.