I have been reading through these forums for quite awhile now and wanted to thank everybody for valuable info that has been provided.

I have a 1997 F150, 5.4L engine, 114k miles. I bought it only five months ago. Soon after I bought it the check engine light came on. It ran ok and I didn't do anything with it. Then, I took my camper out for a weekend and the truck ran horribly. It stuttered a lot, kind of like the feel of a when a clutch slips in an manual transmission. On that trip, the alternator went out, which I replaced. After disconnecting the battery to replace the alternator, the CEL went off, but then came back on when driving. Also, I only got about 8 mpg when towing my camper, and there were not a lot of huge hills, and the camper only weighs about 3700 pounds (well below towing capacity). I only get about 10-11 mpg around town, which seems awful for a stock truck.

I went to the parts store and they read the code as being a "slow response" from the front O2 sensor. They cleared the code and I drove it again, and the CEL came back on. I took it back to have the code read, and now it came up as a "lean" code, bank one.

I have read several posts in here about lean codes and need to go through all of my steps - clean MAF sensor, check vacuum hoses that come off pvc valve, etc. I realize the lean code could be from a bad O2 sensor, or it could possibly be that it is not getting enough fuel. I am wondering if the shuttering caused when I towed (and it does it sometimes when I am not towing, just not as bad) could be from lack of fuel rather than tranny problems. There were no trouble codes related to the tranny, although I don't know if slipping trannies have a trouble code?

Finally, there is a buzzing sound that comes from the engine compartment, especially at idle, and you can hear it really good for just a split second when you shut down the motor. Not sure where that is coming from, but thinking it might be a vacuum leak? The truck idles perfectly though, which leads me away from a vacuum leak, and actually drives decent at times, but then the shuttering will kick in a bit.

My hope is that this truck does not have tranny problems, and that it is a fuel pump, fuel filter, vacuum lines, issue that can be easily remedied.

Any thoughts on this would be greatly appreciated. Sorry to be so long winded.

 

Can you post the O2 code and the Lean code that you got?

 

Yea, we need the codes to help. How does it idle on a cold start once it comes down - Reason - The O2's arent activated on a cold start until they hit about 800 degrees. So how does the cold start idle compare to hot idle when the O2's are in control.

 

I believe the first code read PO133, oxygen sensor slow response, and the second time it read PO171, bank 1 lean. Does that help? Thanks again.

 

Well PO133 is bank one as well - replace both forward O2 sensors on bank one and bank two - your lean code will most likely go away.

 

100k is time for some maintenance. When I bought my truck the first thing I did was drop the trans pan and put in a new filter. Sound to me like you need the basic tune up stuff. Cop's plugs o2 sensors. Maybe take off the throttle body and clean it good. That stuff will make it run better guaranteed.