Lesson learned...
 

In follow up to a previous thread of mine, I've been chasing down the cause of a p020x (injector fault) error. Code comes on different cylinders at different times and only under tow load. Went through the exercise of replacing plugs/wires/cap/rotor. D ran a bit better, but codes kept coming. Took the boat to the Keys anyway. That's when the fun began.

D began to run rough intermittently. Gas milage would plummet to 7 MPG at 60 MPH for about 20 miles and then would return to 11 MPG at 60 MPH for 20 or so miles. Got to Key Largo and noticed a gas smell from the exhaust. Running rich. Rechecked the codes. Now I had p0171 (1/1 Lean Fuel Mix) to go with p020x (Injector Fault). Normally, the p0171 would indicate an air leak somewhere in the system that was allowing excess air to enter the mix, the PCM makes the required addition of fuel and away you go. But that would leave you with a vehicle that was not running as rich as mine was.

No, no. I had an error that was telling me that I had a lean mix detected but CLEARLY had a rich mix in practice. The only answer was that the O2 sensor was providing a false lean reading, the PCM was thickening up the mix and I was getting a rich exhaust instead of a normal compensated exhaust. Swapped out the O2 sensor and everything was fine.

My point is, even though the issue is "typically" related to "something" - p0171 is typically related to a vacuum leak of some sort - you should always look at all of the facts infront of you. If I would have followed conventional wisdom, I'd STILL be looking for a vacuum leak!

Oh yeah, the injector fault errors went away too. They appear to be a byproduct of a bad fuel mix.

WOW!

Thats a great analogy.


Thanks for the update!