2.3L ('83-'97) 96 Ranger 2.3L Constantly Switching from Open Loop to Closed Loop

[SenorNoob]

The only way I can see it running that rich on all cylinders is if the air is super restricted (like new filter still wrapped in plastic, lol), the FPR is leaking (unlikely it'd hold pressure), or maybe the injectors are stuck open.

 

[ksimp]

Just in case anyone is interested, I'm attaching a FORScan capture.
Thanks

 

[ksimp]

@SenorNoob ,
My guess is the one or two fuel injectors leaking caused the upstream O2 sensor to carbon foul (see uploaded pic). So, it was unable to read oxygen content properly, thus giving a false rich reading. The replacement O2 is responding as expected (with the rebuilt injectors).
I did follow @franklin2 's advice and added seafoam to the gas tank. Maybe I added too much?
Thanks

 

[franklin2]

It will smoke if you add too much, though the catalytic converter might hide that.

 

[ksimp]

@franklin2 ,
Well it is still smoking while it is running, and it doesn't smell exactly like gas burning. Also, the engine surges, or searches, while it's running. Almost like it is not running on pure gas. Which made me think there is too much seafoam in the mixture. It's currently sitting on half a tank. Do you think it would pay to fill the tank with gas to dilute the seafoam?
Thanks

 

[franklin2]

You could. Put the good 93 in it and that should dilute it. Just sitting around with that seafoam in it is doing it some good. It's probably been long enough if it was going to do anything.

 

[ksimp]

I think I've found the issue. Filling the tank with 93 octane didn't help. So, I went around unplugging some things to see if it made a difference. I unplugged each coil, one at a time, didn't help. Then I unplugged the MAF sensor. Cranked up and the engine ran normally. The wiring harness going to the MAF looks rough. So, I'm going to try and replace that, first. If that doesn't do it, I'll also replace the MAF.

 

[ksimp]

The MAF sensor was the running issue. I replaced it with a NTK unit from RockAuto.

It still has the idling issue. I goes up and down until the engine heats up to around 140*. Then it smooths out and runs like a new truck. I'm going to drive it for a while to break in the rebuilt engine. I'll probably revisit the idling issue when the weather warms up.