I have a 2007 F150 STX 4x4. All diagnostics point towards a restricted exhaust. Can it be catalytic converters? I had a shop do a backflow test, but they said they were ok. I have also been told that the material in the converters can expand after the truck warms up and can be the cause. Any ideas are welcome...I am past frustrated.

O2 sensors are good
MAF sensor is good
No vacuum leaks
No intake, exhaust leaks
Fuel pressure is good

Code reader pulls misfire and rich mixture at both sensors before the converters. Thanks for any insight!

 

FYI, A rich mixture over a period of time can cause a converter to overheat and eventually become restricted. If the check eng lite has been coming on it tells you something is going on and should be corrected. Unfortunately, after the rich mix problem is corrected , the converter problem now appears.

 

So if I read this correctly, the converters should be replaced? If not, what could be the problem? FYI...I also changed the plugs and none of the coil packs are showing misfires.

 

The emission system should alert you if there is a problem and the emissions are out of range. The fact that there are/were possible mixture problems should be checked out with a scan tool to isolate a particular area with a problem. If it was due for plug replacement, that could have corrected a problem. Replacing the converter(s) without verifying everything else is OK is only half the job.

 

u feel any jerking or misfire...? if u feel anything related firing first arrest that one and check any trouble code related catalyst system like p0430/p0420