Hey guys quick question. Just picked up a new truck. Its an 07 f150 with 130k on it. Don't bash me on miles its a really nice truck and was one owner but I think they cleared the code before I got it now I'm having this issue. Truck runs great no problems but I'm throwing this code and I've read everywhere that it is bad cats. Hooked it up to a scanner and it is running very eratic at the o2 sensors. I believe it was the passenger side being worse than the driver side with it running very lean and the driver side running slightly rich to normal. Code says catalyst system efficiency below threshold bank 1. My buddy is a mechanic and he said that I need new cats. My question was what cats are you guys putting on these trucks? Its the flex fuel 5.4. I figured I could go ahead and get high flow cats if I'm going to put new ones on it but will they throw a code as well? Should I go factory? Also, is there an underlying issue which caused the cats to go bad? I've read some posts on here saying that it may be a possible misfire. What are you guys thinking? New cats and I'm ok or other things needing fix?

 

Try to find out if the spark plugs have ever been changed - if not, they are WAY overdue.

Replace the cats with high flows that have the O2 bung.

 

GLC, thanks for the info. I was looking them up on magnaflow, everyone seems to like those. These are the part numbers for the direct fit ones. Is that what I should go with direct fit or the universal? PN-Drivers side: 49694 PN-Passanger side: 49695.

 

Those numbers don't look right for high flows.

 

So are the high flows universal fit cats? Because those are their direct fit ones. They are direct bolt up. Do you have part numbers for the high flows?

 

94136.

https://www.f150online.com/forums/ex...installed.html

 

Last question and ill leave you alone lol. Are motor craft plugs still the rule of thumb on these motors? And with high flow cats on should I put an aftermarket muffler on as well? Or can I just do the high flows on a factory exhaust? Thanks for all your help GLC

 

Those aren't 'hi-flow' units, just OEM style replacements. So generally, they will keep the volume lower.

You can run the 94136s with the OEM exhaust without anything going wrong or sounding weird.

The Motorcraft plugs are the best for these motors. SP-515s to replace the OEMs, granted your previous owner never had them replaced.

 

Thank you sir I appreciate it

 

Quick last question, I may as well replace the muffler while I'm doing this to get a good sound. What part # for magnaflow would you reccomend for single in either dual out or single out? I want something moderate on the sound, not really wanting cab drone and dont want something crazy loud just a nice tone.

 

19" Borla ProXS. Tailpipes matter to however many you wish to have.