hey yall,
I got a 97 F150 as a gift recently. Engine was rebuilt 5yrs ago, but person opted to remove Catalytic converter. Engine runs great cold, great takeoff when I touch the pedal, and hauls a$$ on the freeway. idling at stop lights are dreadful tho. RPM's bounce up and down below 1K, but never stalls(sounds like it wants too). I have only changed the plug wires so far, would like a 2nd opinion before I do anything else. I read on another thread that no Cat will spit out 2 codes minimum. I had 8 this morning at Autozone. Really only 4 codes but each of them twice. P0171Fuel trim Bank 1 condition, P0420 Catalyst low bank 1 P1537 Intake manifold runner control fault 1, P1538 Intake manifold runner control fault 2. In the military we used jump wires for troublshooting,(trick computer that no fault exists) I was wondering if there was a way to do this for the oxygen sensors, or to remove the cat fault without installing one. I would like to wait until I can afford to run separate pipes on each side rather than Y'ing them together into a single cat and muffler(stock method).
Mainly, I would like your advice as to improve the idling if possible. Exhaust has a rich fuel smell also, if that helps.
Any comments appreciated !!!!!!!

Nate

 

I've heard the phrase "dont look a gift horse in the mouth" and no offense, but your truck qualifies for that. As for your trouble codes, I myself would put the exhaust back to stock condition and just run a "faux dual" after the CAT. and most of your codes should go away. as for the intake, i havent come across one like that yet, and im curios as to know what would cause it. someone else on here will be able to help you out further.

 

Last things first.
Jumping leads etc is a thing of the past.
The system is total software computer control.
You have the problem because there are no operating oxygen sensors.
The system is designed to "go rich" in the absence of the OX sensor functions.
This is why the idle wanders and your fuel mileage should be very poor as a result.
Put a stock cat system back on, then address any other seperate problems per code.
From one code you gave, the motor is a V6.
The truck has just been hacked on by the last owner who didn not know either what he was doing trying to get more power in the wrong ways and/or just one of these people who didn't think he needed all the hardware or could not afford to fix it right.
Good luck.

 

You need to get closer to stock, not add to the madness. The first thing you need to do is replace the cats and run into a single pipe. These trucks are made to run with a single system. You run true duals, you will get lower fuel economy, worse gas mileage, and reduced low end torque versus a proper single system.

You need a get a cat back on there. The cats are not there to make the world a greener place, they are there to consume the unburnt fuel and to maximize power while they are at it. The truck will run better with cats than without.

You need to get a good set of cats. Technically you should have 4 converters, but in your situation 2 will do. Bank 1 fuel trim could indicate a problem with the sensor, but could also be due to a vacuum leak on one side of the engine. It could also be due to an exhaust leak.

You need to get a scanner on there and diagnose what is causing the fuel trim problem. The goal is to get the trim as close to zero as possible. The fuel trim will correct itself when the problem has been corrected.

 

thats the consensus I guess, a buddy at work told me the same thing today. "put the cat back on !" The intake fault has to do with the IMRC, or vac tubes connected to it.