Iooping at idle

[Noob]

I have a 93 ford ranger 3.0L with what I am sure is a 91 engine. At cold start it runs great. But once it warms up it starts to loop at idle. I pulled EEC KOEO codes and had 311 air system inoperative, 173 systems indicates rich bank #1, and 177 systems indicates rich bank #2.
I found a small hole on the air intake hose and patched it with JB weld. The engine runs better. Pulled the codes again and just get 173 ad 177.
But it still loops at idle once it is warm.

There is no check engine light present.

If you've read some of my previous posts you can tell I'm a real noob.

The MAF was cleaned and functioning. The TPS was tested with a multimeter and functions. And the IAC was replaced. I located what I believe is the intake air sensor located within the air filter box. I haven't been able to find a way to test this sensor.

The truck ran rich (you could smell it) when I got it. Could the O2 sensors be bad and sending a rich signal which tells the PCM to lean out the mix and cause the looping?

To identify if it is a problem with the O2 sensors do I just unplug them and see how it runs? Or should I be looking elsewhere for the looping issue? I cannot find a vacuum leak. But to be honest I'm not sure where all the hoses are. The diagram under the hood does not match the engine. But I took a stethoscope to every hose I could find.

You can hear the fuel pump prime the lines when you turn the key. But I haven't checked pressure.
The PCV does have suction and rattles when you shake it.
Air filter is brand new.

Thanks!


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[RideFord94]

Have you cleaned the egr?

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[Noob]

I don't believe it has an EGR. The Haynes Manual says that 1990 and later 3.0L are not equipped with an Exhaust Gas Recirculation system.


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[RideFord94]

Hmm. My 98 has one. It usually is a pipe that comes up from the left exhaust manifold and the valve assembly meets up to the intake manifold behind the throttle body. If you suspect the O2 sensors I cleaned mine out with brake clean/carb clean. It helped my gas mileage a bit and she ran smoother but I should still probably replace them.

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[RideFord94]

I heard they tend to get lazy around 80k miles

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[Noob]

So I forgot I unplugged the MAF to take the pictures. Started it up. The check engine light came but it ran great. Even drove it about a mile to work without problems. I've already cleaned it so I think I need a new MAF.


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