How do I make my truck stop running lean?

Question

My engine light is on in my 1998 Ford Ranger XLT V6 4.0 Liter 2WD, my friends parents own a car dealership and he hooked it up to a computer and said that my truck was running lean and that the light being on is not going to affect my inspection. I just want to double check before I spend money on an inspection and have it fail. Also, is there a way I can have the light off permantle by fixing the problem not having him turn the light off with the computer?

Answer 1

Oh, a 4.0L.

How about fixing the intake manifold gaskets before you destroy the engine?  That's what the P0171/0174 is signaling and it's very common.  

If the lady I talked to at NTB was an indication, you'll need $900 or just ignore this and get a new engine for a few thousand bucks.

How's that for a thought?

Answer 2

1. take the injectors out and have them cleaned on a ultrasonic cleaning bench. ( alot of the time people spend lots of time and money on other things and ignor the injector problem becasue its so expensive)

2. Check the exhaust back pressure.

3. Check the air filter

4. Check the fuel pressure

5. vac hoses.

6. pull just the MAF sensor out of the air box (usually two little tamper proof screws) Clean it carefully with carb cleaner and a razor blade to scrape the dirt off. Be V E R Y  gentle.

7. Most of the time O2 sensors work backwards when they go bad it runs to rich..

Answer 3

Usually if there is a problem, and its just cleared, it will pop back up in 50 miles.  This can also show hidden, without a light before the light actually pops up.  So yes you could fail.  

You might start chasing your tail, depending on where you start.  Running lean, may just be a clogged fuel filter.  Depending on miles and if its been changed, ive seen some plugged at 50k miles.  Maybe a vacuum hose running to the fuel pressure regulator, or the regulator itself.  Fuel pump dying.  

Honestly, it might be an input, meaning a sensor, like the map sensor failing slowly, causing a lighter demand, or leaner condition.  Hard to say, but try a fuel filter if youd like.

Answer 4

Addition to the answer above...

Clean your MAF.  They can get coated in dirt and that will throw off the barometric pressure calculation.

Answer 5

guaranteed to fail. If the engine's running lean, the HC numbers will be low, but the NOx numbers will be through the roof. Running lean could be caused by:

low fuel pump pressure

plugged / fouled injectors

dying map sensor

dying O2 sensor

vacuum leaks

inaccurate engine coolant temp sensor

After the repair is done, the mil light should be reset by clearing the codes via the computer reader.