Recently the Check Engine light would come on for a day or two and go out. Today it began flickering (later stayed on solid) and it had a loss of power and began running rough. The engine has 310,000 miles. What could this be.

Diver Doug

 

At 310,000 miles it's probably telling you that it's tired and it's time for a rebuild. How is the oil pressure gage reading? Is it in the middle and steady or low and sometimes fluctuating rapidly? In the middle can still be low oil pressure as the gage will read "normal" at 7 psi and over.

 

Thanks for the response. Oil pressure is good, always steady. The gauge reads a bit above the middle. When the milage was just about 200K I replaced the heads (pin hole leak had developed leaking out coolant). That was about 4 years ago. The truck has run great ever since then until now. Now I am thinking maybe the spark plugs. Does a check engine light occur when plugs start to mis fire? Or could this be a coil problem?

 

[quote=diver doug;9249373]Thanks for the response. Oil pressure is good, always steady. The gauge reads a bit above the middle. When the milage was just about 200K I replaced the heads (pin hole leak had developed leaking out coolant). That was about 4 years ago. The truck has run great ever since then until now. Now I am thinking maybe the spark plugs. Does a check engine light occur when plugs start to mis fire? Or could this be a coil problem?[/quote]


It could be either and it will usually cause the CEL to come on and set a code.

 

I had the same thing happen to me and it was a spark plug problem.

 

It is a misfire. Pull your fault codes so you know where to look. Most common failure is a COP.

 

Thank you. I did realize the plugs had about 113K on them so I changed the plugs. For a few days the Check Engine light was off but the truck still had some hesitation and misfiring. After three days when passing on a hill the cutting out came back and the check engine light came backon, flashing. It flased for about 20 minutes and then stayed on continously. A few hours later the light is out. If this is a coil problem wouldn't I have continous sputuring and the light on?

 

READ THE CODES! DO NOT GUESS.