The question is: Could using a BFH to loosen the exhaust pipe cause 02 sensor damage or anything else to cause severe missing?

Installed the Dynomax catback today. The old muffler was seized on the cat so I tried lots of PB and a BFH to no avail. I ended up prying the old muffler flange off and shook it loose from the cat. There was a fight, for sure.

During test drive there was a bit of smoke, which I figured was normal. Then the engine started missing pretty bad. It would miss intermittently and then have full power for a while before missing again. I tested again a couple hours later and no smoke, but same intermittent skip. The RPM's are all over the place.

The system bolted up great and the extra oomph is obvious. The 02 looks ok and connected, EGR never acted right, but this engine never missed before either.

My guess is I knocked the 02 loose or something. Will that cause such a symptom? EGR?

 

Although the O2 sensor sounds like the issue, and sure how you hit or what you hit with the BFH, but take a look at your cat and look before the cat to see if you cracked anything. When it comes to exhaust, I usually cut and weld things on and off. If you cannot weld, you can buy clamp on pieces. JB

 

I thought the same. I just swapped mufflers and I had some big problems. My fuel pump ended up cutting out. Had nothing to do with the install. Just a coincidence. So make sure you look outside the box. Make sure you test everything before you start throwing money at it.

 

How about an almost burnt through cps wire? Found that it was contacting the front pipe while back probing the 02.

That's gotta be the problemo.