Bad o2 or bad cat?

[j91z28d1]

can't tell from the pics. if it possible to take it apart and inspect the cats visually?

but yes, a plugged up exhaust can cause spark knock.

 

[crownvic31]

Btw i just want to correct something on the cats that i am using.

The ones i am using are these:

MagnaFlow 54959 MagnaFlow Universal Spun Catalytic Converters | Summit Racing

Free Shipping - MagnaFlow Universal Spun Catalytic Converters with qualifying orders of $109. Shop Catalytic Converters at Summit Racing.

www.summitracing.com

 

[crownvic31]

Guys I am at lost here.

Its been a few weeks since I updated but I have no other solutions.

So truck is still doing the same. Ive replaced coils and fuel injectors and yes OEM and pretty expensive. Also replaced rear o2 sensors OEM. All cylinder misfiring, low engine performance, loud vacuum on the driver side rear around the valve cover and exhaust smells some what like burnt gas.

truck parked, 2500RPM STFT are switching between -10 and +10. LTFT are steady at +9.
while I was parked and rpms at 2500 I noticed that both cats were reaching high temps pretty fast. Bank 2 made it to 1043 and bank 1 to 1020. this was holding the rpms at 2500 for about 15 seconds.

 

[crownvic31]

Also,
Ive done several smoke test as well as my mechanic shop and I have zero leak. Can it be possible that my cats are bad causing some kind of back pressure? This is so hard to diagnose.

 

[blondie70]

You could pull out the front O2 sensor and run it to see if it runs better....quick way to reduce back press. Good Luck

 

[crownvic31]

Ok so this is a reading of the o2s. 1st one and 3rd are front o2s. 2nd and last are rear. This is running. Those rear o2 sensors have to much activity i believe.

Can anyone verify this?

 

[crownvic31]

So i did a on board monitor and this showed up. Im guessing that thisnis a bad cat?