Magnaflow cat emissions-FAIL-

[hoveringuy]

So I just upgraded the exhaust from the e36 OBD2 system I had been running for the last year. I replaced that boat anchor with a Magnaflow metal cat/ Borla combo.

The old system passed fine, the new system failed for HC at idle and was generally dirtier for CO. Update: see post 6 for the retest with factory cats swapped back in
e36 m3 cats

. ............HC (ppm).. CO(%) ..CO+CO2(%).. O2(%)
limit .......150 ............1........... 6.............. n/a
cruise .....49........... .16 ....... 15.6........... .16

limit .......220.......... 1.2......... 6............... n/a
idle....... 154........... .02....... 14.92............ .87


I may try throwing the old system back on and retesting tomorrow.
Magnaflow universal

............. HC (ppm).. CO(%).. CO+CO2(%).. O2(%)
limit............ 150...... 1............. 6............ n/a
cruise......... 125..... .81.......... 14.61....... 1.46

limit............. 220.... 1.2............. 6.......... n/a
idle............. 343..... .2............ 13.5....... 2.32

[Jalves619]

How many miles have you put on the Cats? You might want to call up Magnaflow and see how long their break in period is, if they have one.

[hoveringuy]

Maybe 35 miles. Enough to get them nice and hot a few times.

[Jalves619]

I've read in the past that it can sometimes take up to 100 miles for cats to break in, but it mentioned it in regards to oxy sensor and ecu calibration. I'm not sure of how the "break in" that they describe would affect your emissions directly, but its possible that your computer is overcorrecting for the wacky mixture readings its getting. Or I could be entirely wrong.

[hoveringuy]

I've read in the past that it can sometimes take up to 100 miles for cats to break in, but it mentioned it in regards to oxy sensor and ecu calibration. I'm not sure of how the "break in" that they describe would affect your emissions directly, but its possible that your computer is overcorrecting for the wacky mixture readings its getting. Or I could be entirely wrong.

I have a wideband and it's been reading 14.7 at idle and cruise so I think it's plently adjusted. Like I said, I hope to have it retested with the factory cat tomorrow which should be interesting.

A direct comparison!

[hoveringuy]

Retested today with the M3 cats back on. Same station, same lane, same operator. Same underwear.

Red is Magnaflow cat.
Green is OEM cat

............. HC (ppm).. .....CO(%).. CO+CO2(%)........ O2(%)
limit............ 150........... 1................ 6................ n/a
cruise........125 54...... .81 .08 ... 14.61 14.88.... 1.46 .25

limit............. 220......... 1.2............... 6................ n/a
idle........... 343 64 ...... .2 .01 .. 13.5 13.81 ......2.32 1.58

Clearly, the factory cats do a much better job than Magnaflow. The Maggy's are Ok, but with the OEM equipment I had baby Koala bears and ducklings coming from my exhaust.

Also, conventional wisdom is that HC is due to unburned fuel in the exhaust and has nothing to do with the cats. My wideband showed 14.8 during the failed test at idle and I don't have any misfires.

Case closed.

[reelizmpro]

This is strange for a cat that isn't blown out. I've replaced a few cats on my other car and passed instantly with 0 miles on them. From the muffler shop, straight to the smog shop next door.