Guys, I found your board by searching for a fix for my car.

my 4.2L 98 F150 4x2 keeps hesitating when accellerating and almost stalls at a stand still. Check engine light came on, it registers as "Right and Left" bank running lean. I have replaced the 02 sensors twice no luck, new plugs and wires no luck, k&n air filter installed no luck, new fuel filter no luck... Please advise..

Thanks,
Jeff

 

Glad you found us and hope we can help.
Have you changed the fuel filter? Consider also the fuel pump.
Other possibilites yes, but I'd check first things first. Sound like you are in the process of doing that.
I'd guess a bad (or dirty) MAF sensor could also cause problems if it is supplying inaccurate air flow data to your computer.

Hope we can help and again, glad you found us here at FTE!

 

May also want to consider a throttle position sensor. Also the Intake Air Solenoid.

 

ok, checked maf, its clean. bought fuel filter, project tommarow a.m. Will i ruin the motor driving lean?

Jeff

 

If it is truly running lean, then theoretically you can burn a piston, or a valve. Pull your plugs one at a time and lookat them. If they are white and very clean, youare running lean. If they are a light tan to medium brown, then you should be alright, but this is just a "shadetree" way of checking. The only real way, would be to have someone hook it up to a complete diagnostics machine. They should be able to check fuel pressure also. BTW , are you clearing the codes from the computer after each attempt to fix? If not they will take a long time to go away themselves. Just disconnect the battery, go have a sandwich, and hook it back up, and away you go.

 

burning a piston or valvue happen that often because of running lean? The truck makes some strange noises since this has occured.

Jeff

 

It depends on how lean you are running, how far you drive,how fast, there are alot of variables. It's all just speculation until you prove it's lean or not. As for noise, if it's truly lean, then you will have spark knock, or detonation on 87 octane fuel, maybe even89 octane. Don't try too hard to come up with trouble,I have done this myself many times, most recently w/my overheat problem, sometimes we start hearing things that may be normal otherwise, but w/engine light on, we start to "imagine".

 

Oh no this isn't natural. I have put two 4.2L of the identical year next to each other, plus it stalls at stop lamps once in awhile.
Jeff

 

Check this website out;
www.leakingfords.com

 

stalling sounds like a fuel related issue. You mentioned looking at the fuel filters and pump, let us know how that works. Also, what about injectors?
You wont actually do damage to the engine by running leaner than normal, as long as you dont here any detonation or pinging from the engine.

Garrett

 

I have been hearing pingin since 50,000 miles those ****** at ford told me it was a heat sheild vibration. Now that I think about it, it has been getting worse.


Jeff

 

Pinging huh? I suggest a SeaFoam ingestion.Also,a throttle body cleaning.I prefer CRC-TB cleaner.You might also want to clean your IAC valve too.Use the TB cleaner on it too.If you do the SeaFoam ingestion change your oil afterwards.Good luck and keep us posted.

 

BlueOv,
Throttle Body is cleaned, IAC is clean. As for seafoam I have never heard of it, what does it do?

Thanks,
Jeff

 

It cleans the carbon from the valves,pistons,and some of the intake.There is a thread in this forum about it.It very well could benefit your 4.2.BTW,how is your coolant level?

 

most definately...pinging is a bad bad thing....you need to raise some hell.

Garrett