Hey guys, I found out the source of my misfire headaches. Bad Magnaflow cats.

Can someone tell me how to delete the rear o2's with EFI live?
I'm running open headers until I get this problem resolved.

Thanks

 

Someone will correct me if i'm wrong but I think you go to your tune tool. Engine Calibration / Cat Converter / Parameters and disable B0701

 

In the engine diagnostics DTC's, set everything with O2s bank 1&2, sensor 2 to "not report". Should be about 8 things if I remember right. Also set P0420 and P0430 to "not report" also. Do the same thing in the DTC's MIL enabler too.

 

It looks like everything was set correcty but I still get an emissions light. I will have to run the codes tomorrow and see what popped up. To loud for night time...

 

Well, I thought the cats were the problem... But low and behold it's still misfiring like a bitch. It looks like Justin turned all the 02 codes off last time he worked on my tune. The first time I drove it after no cats it ran fine, second time and there-on it got a p0300 epa and a regular p0300.

This is the list of what I have done to troubleshoot thus far:
- Swapped Plugs NGK TR55's w/NGK tr6's
- Swapped Plug Wires and put back on stockers
- Swapped Coils around
- Did Compression test and Leakdown test
- Checked fuse box for bad grounds
- Put in new Walbro 255 fuel pump
- New Fuel filter
- Seafoam in fuel system and PCV
- Ripped Cats off
- Put turndowns on open headers so front O2's aren't picking up pure oxygen.

Things I have not done:
- Swapped rear 02's with front ones (maybe they were bad because of cats backing up.)
- Pulled injectors out to clean them
- Put stock plugs back in

Guys have any more ideas?

 

maybe a bad injector???

 

Are you getting a lot of misfiring that you actually feel, or does it just keep throwing the P0300 code?

 

Mine was missing real bad and it was because of a bad front o2.

Log a run and look on Dashboard B at your voltage on the o2 sensors (ho2s11 and HO2S21. if its moving up and down its working.
Here's when my bank 2 went out.
Log_0000
And when I fixed it.
Log_0006

 

check the plug wires, especially the top on the coils. Its so easy to not set them in all the way.

 

btw. when my o2 went out it didn't throw any codes. but it's worth checking.