Hi to everyone I have been looking on this form and working on my truck for over a year. I have a 1997 F150 4.2 2 x 4 base model standard cab. I have been working on this truck with Mechanics for over a year now. Between me and 2 mechanic no one can figure out what is wrong even with computer diagnosing equipment. Here's what has been done new coil pack new wires new plugs one catalytic converter was clogged. both replaced new O2 sensors both upstream and downstream. New maf Fuel rail pressure tested okay injectors taken out cleaned and tested okay exhaust back pressure tested after catalytic converters are placed okay intake smoked for 2 hours no leaks compression test okay no exhaust leaks around the manifold all studs are good. I have looked around on other sites and here and can't find anyone having a problem like this. bank 2 long fuel trim is locked in at plus 25 Bank 1 Long fuel trim sits at 0 to + 14 how ever under load it will jump to +24 this all started when a catalytic converter clogged the mechanic forgot and couldn't tell me what side it was on. and ever since then I have not been able to get this truck right I can't find the problem one mec keeps saying need a new ecm. can't afford to drive it as it is burning way to much fuel and can't pull a hill at 60mph with nothing in the bed. Has any one had anything like this can it really be the ecm or something else? I am flat out of ideas the mec that has worked on this truck for 6+ years with 30+ years of experience has never seen anything like this. I am at a tolatal loss I have checked every flipping thing that connect to that engine hoping to find something cracked broken or not hooked up. Any ideas?

 

leaking intake isolator bolt seals?
plugged up intake manifold EGR ports?

 

Were the O2 sensors replaced with cheapies or quality ones? I've had people come to me after installing the $12 ones off eBay or Amazon only for the new O2 sensors to be the problem.

 

O2 sensors are Bosch specifically for my F-150.
my Palladium is the metal version before they went to plastic it has the upgraded new gasket as far as I can tell it don' have isolators for that old version. There was quite a bit of buildup of crud inside the Palladium when I was working with the injectors. I cleaned that out and figured that the lower manifold and valves are probably rough as well. so I put the CRC intake valve cleaner through the engines and I actually noticed that when I was feeding the engine with that CRC cleaner the fuel trims would match each other exactly. I will go back and check the egr as far as clogged intake as much crc valve cleaner and sea fome and how smoth the engine idle is now I don't feel like intake clogged would be an issue but I will check it with a borescope.

 

Did you say you replaced all 4 O2 sensors? Is it possible you placed an upstream in a downstream hole visa-versa? If not, maybe try switching your front O2's side to side, clear the KAM and see if the fuel tables climb on bank 1 instead. Perhaps you've done that already.

 

Yes I did swap o2 banks no change I did see that bank 2 was runing clean how ever bank 1 did not look as clean. Makes me think bank 2 is trying to compensate for 1 how ever still need to check the egr and intake for any blockage how ever wether has put me on hold

 

list all of the codes that are shown.

 

only one code P0174
i did not get the borescope down passed the palladium then the bat died. so my 4 hrs to work on it was shot had to keep moveing on down the list. will report back findings next time i can take a look at it

 

Ok so update so I used aimsoil power foam and wow. Clean as new as far as I can get the borescope. I Was runing it I was so happy it is fixed both long trims where in line with only .5 discrepancy. Then all the cleaner burned off and bank 2 peg back at +25 on the long trim at this point I dont know what to do.

 

 

The mechanic that did the smoke test saying he did not see any smoke form any where. To be honest I do not know if he checked the evap. I can try and clamp the evap hose to the engine with some vice grips and check the trims. I need to buy a smoker as I got a 83 diesel Mercedes and it is all vacuum operated. How ever I want to try and build my own smoker frist.

 

If the motor runs ok otherwise but just the code, there is likely an air leak just ahead to the front Ox Sensor for bank 2,.
This would 'falsely' richen up fuel by shifting the LTFT causing the code to set..
Carefully listen for an exhaust leak near the head pipe area and exhaust manifold. Might even use a stethoscope with the probe removed to hear it..
Good luck.
.

 

Well it will run rough from time to time. I know I got a leak after bank 1 o2 where the manifold clamps to the pipe to the cat. As I see it smoke and hear it from the sea foam treatment. But I did not think that will make it peg bank 2 at 25

 

You cannot just ignore those issues and second guess a computer system like that.
Repair everything you find.
More than one problem at time really causes confusion.
No wonder it can't be figured out!
Good luck...

 

That is why I am here I do not think it is the ecm. Like the mec and tec think.