Tricked by the AFR gauge.

[TrailBeast]

Some time back I was driving along down around Phoenix and my car started missing.
I looked at the AFR gauge and it read 19:1 or some such nonsense. (Way lean)
Ok, failing fuel pump so I stopped and picked up another pump in case I had to swap it out somewhere less convenient, but it ran fine on the way home.

A week or so later it did it again, so I swapped in the new pump.
A week or so later it did it again.

It tricked me.
The AFR gauge was showing super lean not because it was lacking fuel, but because there was an intermittent ignition module misfire leaving unburned oxygen in the exhaust.

Brain fart.

 

[67Dart273]

So, how did you find the problem? I admit that would probably throw me off

 

[TrailBeast]

So, how did you find the problem? I admit that would probably throw me off

It finally occurred to me that the motor wasn’t hiccuping and stalling or popping back through the intake.
It was a sudden on/off thing.
Then I finally realized the lean reading was from unburned oxygen.

I always carry a spare 8 pin module in the trunk in my little accessory box, so I swapped out the module and no issues since.

 

[Bewy]

The next time I use an AFR meter....will be the first time.