My trucks pulling a lean code ??

My Ford was giving a lean code. After several unsuccessful attempts to fix it, I put a couple of bottles of injector cleaner through it and the problem went away.

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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if you truck has an upstream O2 sensor and a downstream O2 sensor.. you will not get a lean burn code and it being a 02 sensor. as one is checked off the other one. when engine is started COLD.

as the converter does no work cold. so exhaust in is the same as exhaust out.

but it could be a dirty mass AIR flow sensor.. clean it first.. otherwise replace.

A restricted fuel filter can cause a lean code as well as a failing fuel pump.

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?

Chuck_thehammer wrote:
an intake leak, hose or manifold ... pull extra air into engine.

cheap and easy check.. with engine idling, use WD40 and spray around vacuum hoses and where the intake makes contact with gaskets and heads, and a round the TBI.

the idle speed and pitch will change when the WD40 enters into leak.

Start the vehicle and let it idle. Take a propane torch. Open the valve. But do NOT light the torch. Point the tip of the UN-LIT torch (with gas flowing) around hoses, head gasket surfaces, etc. When the idle picks up (increases) you have found the (at least one) source of the leak.

I would change the o2 sensor on the left side first

maybe mass air flow sensor ?? I did clean it about 5 months ago but might need more. I will try spraying wd40 or water near intake gasket to see if motor revs up or stumbles. first time a light has appeared on this truck so I wont jump to quick at it. This old chevy pers like kitten !!!!!!!

I just got the same code intermitantly on my 5.3. Changed the intake gaskets on several recomendations (about 2hrs and $50). Thoight it was good but the code reapeared. Ohwell she still runs good and the light is out most of the time.

That's real good advice with the wd40 thanks I am going to try that