ok i know there are dozens of these threads but i believe i need to make another so you guys know my situation

i have a 1997 ford f150 4x4 5sp 4.6L triton with 144,000 miles. this truck has sat for since 2014 and i just recently got it running, heres everything i have done so far

• motorcraft plugs wires and coil packs
• rebuilt the entire intake aka new gaskets lower plenum oring and injectors
• cleaned throttle body elbow and removed all carbon deposits (including main intake as well)
• triple checked and smoke tested all vac lines
• flushed all fuel lines; new fuel filter and fuel pump assembly
• new egr valve and line with new manifolds
• new crank bearings and timing chain with guides; cams are within specifications
• new starter and stage 2 clutch with lightweight flywheel with new slave and master cylinder
• front and rear differential are also rebuilt

only things i havent done is put new cats in due to the fact that well i havent had the chance last owner did a cat delete.. now this truck sometime like to accelerate and sometimes from a dead stop it acts as if im towing a boat or a car behind me... im at a loss... oh and if yall must know ithe only reason i have done most of this rebuild is because it was bound up with rust pretty bad.... compression isrunning average 145 psi per cylinder, only cel is bank 1&2 sensor 2 o2 sensors

 

IMHO, it sounds like you have an ecm issue because of deletion or shut off of the downstream O2 sensors (common with cat deletion). Let me explain.... defeating the downstream O2 sensors- is just plain stupid! The ECM calibrations have an “inferred catalyst temperature protection model” which constantly calculates the temperature in the hottest part of the hottest catalyst. This calculated temperature is based on many PCM parameters, such as engine speed, load, ingested air mass, time, inlet air temperature, EGR flow rate and many others. When the catalyst model calculates that the catalyst temperature is about to exceed a level that is safe for the catalyst (generally around 1650 deg F), the PCM will richen the A/F mixture as necessary to lower the exhaust gas temperature and cool the catalyst. This richened A/F ratio will decrease power output, but is absolutely necessary to keep the catalyst from being permanently damaged and without the downstream sensors, the PCM can easily, consistently and once too many times over or under richen the A/F mix...making what a software engineer would call, "An erroneous conclusion"... as there is also a "model" for oxygen sensor protection and exhaust valve protection that when not taken into account can cause internal damage to both the exhaust valves (ie Valve Tuliping)....and yes, this does pull HP away from the engine only for component safeguarding....so my swag is the ecm is operating on erroneous readings and basically pully power away from the engine as part of the protection programming.

 

So go to a muffler shop have cats installed and then test to make sure all o2 sensors work?
and go from there?

 

I don't understand this explanation of the rear Ox Sensors for the following reason.
The rear Ox Sensors only monitor oxygen storage in the CATS.
This is the means that has been provided in software to evaluate the health of the CATS..
The operation is based on monitoring the switching ratio between the forward and rear sensors.
Normally the rear sensors do not vary much if the CATS are storing oxygen as they are supposed to do. After all they are oxygen sensors only.
If the rear sensors begin to 'follow' the front sensors in switching, the ratio reduces.
When the switch radio limits are reached in program, a code is set. as 420 and or 421. These codes are catalyst efficiency has been reached which is a failure of the cats to perform within specifications.
If the sensors are physically missing, other codes are set on addition.
These code do not have any effect on system fuel or operation otherwise.
.
Reference pages 24 to 27 in the OBDII Ford document.
.
The CATS should never go much above 800 degrees F in normal operation or their substrates are in danger of melting.
For reference, 900 degrees is just beginning to be a visual dull red in low light levels.
If 420/421 codes are in too long, the CEL could be turned off for those codes because the system does not look at the sensors any longer since they provide no worthwhile operating info or affect the engine control system or drivability..
If either a code clear is done or a computer re-boot is done, the new diagnostics detects the failure again. and re-lights the CEL lamp.
Beyond this point, you need to look at the system with a Scanner to see what data is shifted out of normal limits.
Good luck.