I just iinstalled my magnaflow...If someone had to get the first messed up one it had to be me...Good Ole Luck O' the Irish :evil: , 2 hrs of grinding and viola I can start the install, mid pipe was cake just perfect....Then 2 of the hangars on the muffler were mis-welded....out come the channel locks to gettt hangars somewhat straight. Now I can finally install mufflers. The job took me 6 hours.:???:

Here is the problem, After the magnaflow when I start the Mini it is running extremely rich, I can see the black smoke from the exhaust in my rearview mirror. It idles irratically, as well as rather high about 1700 rpm. The car stumbles and stalls for the first 5 minutes and smells very rich. Once it is warm It runs wonderfully, Idle comes Back to 700rpm, and no stumbling...

I talked to Randy and he suggested reseting the throttle body plate, which I did...Seemed to help but I think the car had warmed up by then. I am afraid when I was wrenching on the stripped bolts I May have pushed the rear o2 sensor into the heat sheilding... Would a damaged O2 sensor cause this?

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2003 MCS, 2002 WRX 220whp, 1951 Chevrolet 360whp.

 

Tim,

Can you disconnect the O2 sensor and see if it makes a difference at startup? It might not help, but it might give ou a baseline for comparison.

 

Tried the O2 removal and it ran much worse...I tend to believe that the Computer is just reprograming itself. The problem has gotten slightly better every day, start up is smoother and the rich condition only lasts for about 1-2 minutes compared to 5 minutes. I know this is realy bizarre, I assume it is probably an issue of Altitude (I live at 8000ft ASL). Thanks for the input.
Has anyone else had this happen? Running rich after Just a Catback?