My trucks pulling a lean code ??

BurbMan wrote:
I would agree on the O2 sensor. Here is a way to test the O2 sensor to see if that is the problem.

If you have the actual code I can look up the diagnostic tree in the shop manual if you like. Is this the 5.3?

I agree the oxygen sensor is a likely culprit. A 2000 Suburban should be using port injection rather than TBI (throttle body injection), so therefore it is unlikely that the problem is all four injectors on one side. TBI normally uses one injector for each V8 bank and if one side fails, the entire bank is affected. The mass air flow sensor always affects both sides if it is single hot-wire.

The test shown on You-tube does seems a bit rinky-dink, but it inspires further investigation. It does prove whether the oxygen sensor reacts or not. The tech mentioned himself that the sensor would respond to both heat and oxygen level, so once the sensor is hot, the reaction could be oxygen level, or lack thereof, of exposure to the Ox-depleting propane flame.

Using a high-impedence multimeter, a man should also be able to measure underway, and see his Oxygen sensors work while driving the truck. By high-impedence meter, I mean that the meter should take very little current to operate and not drag down the meager voltage by it's own greedy sampling. The sensor on the lean bank of cylinders should measure different than the normal side, and if one was ambitious, he could swap sensors side-to-side and prove that the error was the sensor, if the error-measurement moved with the swap, or prove that the bank is truly lean if both sensors read the same in the same hole. In reality, this is somewhat impractical to sample both sides underway, but one could theoretically measure the sensor in place without removing it, perhaps even in the shop.

Somewhere around here I have a detailed GM fuel injection book, but it has been a while since I read it.

Wes
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