Check engine light on but runs better

[GSpan]

Heres a good one. My check engine light comes on every so often and won't go out until I disconect my battery. I do notice and increase in power, and much better gas milage when it comes on. Just for the hell of it I drove a tank full of gas with the light on, and my gas milage increased by 4 mpgs. Does anyone know why this is, and can I get the truck to run like this without the engine light on?

 

[shamaal]

When the light comes on, bring it to an Autozone or similar place, and have the codes read for free. Post the results and await adulation and praise.
You most certainly have my interest!

 

[GSpan]

Engine light came on this afternoon I'll take it to Auto Zone in the morning.

 

[NightRock]

its very interesting to know... give us the feed back

 

[mrboyle]

The reason is because there is a problem with one of your sensors. With out the light on the sensor is giving bad enough readings that the computer is trying to compensate by adjusting the fuel and or timing to meet its desired parameters. Once the sensor finally exceedes the set parameters and sets the CEL the computer goes into a fixed mode and no longer adjusts its parametres, thus not changing the fuel or timing curve. The fact you are getting better fuel economy is just a fluke and could likely be dur to the fixed parameters leaning out your engine (which isn't good on the engine or cat). Do yourself aand your X a favor and find out what the problem is, then fix it. You aren't helping anything by reseting the computer everytime the CEL comes on, your only delaying the inevitable.

 

[Turdle]

its very interesting to know... give us the feed back

+1

 

[GSpan]

The reason is because there is a problem with one of your sensors. With out the light on the sensor is giving bad enough readings that the computer is trying to compensate by adjusting the fuel and or timing to meet its desired parameters. Once the sensor finally exceedes the set parameters and sets the CEL the computer goes into a fixed mode and no longer adjusts its parametres, thus not changing the fuel or timing curve. The fact you are getting better fuel economy is just a fluke and could likely be dur to the fixed parameters leaning out your engine (which isn't good on the engine or cat). Do yourself aand your X a favor and find out what the problem is, then fix it. You aren't helping anything by reseting the computer everytime the CEL comes on, your only delaying the inevitable.

This is good to know. I'm going to take it in to Auto Zone in the AM. I tried to do it this weekend, but they were swamped and could'nt get to me. Some one told me the samething about the sensors and said its most likely an O2 sensor. Thanks for the info.