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I am working on the new mother-in-laws '96 F150. It only has 53k on the clock, is rarely driven, and when it does get exercise its only short trips. Good news is she takes it to get the oil changed regularly. The check engine light blinks on randomly, and it is throwing O2 sensor lean codes on both banks, upstream sensor. I am guessing that I need to replace the O2 sensors, but everywhere I look I see 3 different part numbers, anyone know what the part # should be? 5.8L, 4x4, AT. Any other thoughts on what would cause the codes to be thrown? I replaced the cap/wires about 2 years and 2k miles ago, plugs looked ok at the time. Unfortunately most of my mechanical experience is with carbs and points ignition systems, so I am a bit of a loss here. Friggin computers. Thanks for the help.
How about a fuel filter? Cheaper, easier to get to. Certainly can't hurt. Its on the driver's side along the inside of the frame. When you are at the auto parts store picking up the filter, make sure you get the Ford Fuel line tool. Otherwise, you'll be fighting those fuel line connectors for hours.
This truck is still very similar to the points ignition you are accustomed to. Fuel delivery is just a little different. We were all intimidated by this at some point or another. Does it feel like its starving for gas?
Do a full tune up when time permits (same stuff you would do on a carb engine). Again, it can't hurt.
list the part #'s here, i would google the part #'s and see if there are descriptions there and see if that helps. i did some exhaust work on my 95 and i haven't gotten the o2 sensor reconnected and i disconnected my egr. i find that the light comes on after a couple minutes, then stays on untill i shut the truck off. then you have to drive a little bit to get it to come on again. if it's going on and off then it's probably not the o2 sensor. the only time i ever had the check engine light come on breifly was when i ran really low on oil
No bogging or any sign of fuel starvation, it pulled a loaded u-haul trailer on the freeway yesterday at 75 mph and inclines with no problem. Only indication of a problem is the occasional check engine light and the codes that were thrown. I read another post about the MAF being dirty and causing the O2 sensors to try to over compensate, which might cause the code I saw. I will try to clean that as well. Will the computer reset and be clear of codes if I disconnect the battery for half an hour?
the only time i ever had the check engine light come on breifly was when i ran really low on oi
That's odd, the computer doesn't know what the oil level is.
The MAF is fragile, so be careful when cleaning the sensor elements. Rubbing alcohol and a q-tip works well, just be very gentle. The codes should reset if you disconnect the battery and turn on some electrical device such as the lights. From what I understand (I'm not as familiar with OBD-II) there are capacitors in the newer computers that must discharge to fully erase the memory (which can also happen over time, turning on the lights just speeds up draining the capacitors).
Sorry, but it sounds like a vacuum leak to me or maybe low fuel pressure.
I would'nt replace the O2's yet. Since both upstreams are throwing lean codes I'd rather suspect too much air getting in or not enough gas getting in.
Yeah, I get lean codes for both banks on my truck. Have for a couple months. I replaced the o2 sensors (the 2 upstream/before-cat ones) on my 96 a few weeks ago, it didn't stop the lean codes :/
I cleaned my MAF sensor by spraying it with electronics control cleaner as well.
I replaced my fuel filter and noticed a huge improvement in acceleration. My CEL didn't come on for a few days, and I thought I had fixed the lean problem.
It is now back
These lean codes are the toughest, apparently they could be caused by a million different things. :/
I agree with Popa Tim... An O2 sensor code does not mean that the sensor itself is bad, it could just be doing its job. Definetly check the fuel pressure before spending $100 on sensors.
I just replaced the fuel pump in my '92 5.0 5 speed 2 wheel drive, and as soon as I did, the check engine light comes on within 5 seconds of strtup, regardless of air-temp, and the truck runs really rough, bogs down, and acts like it running on 6 or 7 cylinders.
Pulled a code, indicated heated ("Hego" sensor, according to the book I have)
was bad...
So, anybody know what other years and model of F-150 will interchange with mine, I want to borrow someone elses O2 sensor and try on mine, before I drop 50-80 bucks for one.
Dad has an '89 4x4 5.0 5 speed 1/2 ton, its different than mine...