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U bend behind catalytic converter



This has got to be a fricken TROLL. Hey SGT whats your name. Post a pic of how that factory downpipe is attached to your SD headers. Better yet, post a pic of the headers installed.
 
Oh ye of little faith. I have a 2.5" pipe welded in there now. Welder was able to get it done yesterday. Funny thing is that the magnaflow catalytic converter I put in a couple years ago was coming apart so it was good timing.
 
and i bet your boost went down again and the kr you had is long gone now. thats a hell of a pinch off from a 3 inch dp to choke through.
 
I ended up with a vacuum leak under the supercharger so I re rtv'd the supercharger and am waiting for it to set up a bit before I check it out. I'm willing to bet I will have at least 1 pound less of boost.
 


still havent figured out the vacuum leak, took the supercharger off and put new rtv on, rtv should be plenty dry after sitting in the garage for 18 hours. fired it up this morning to see what happened, and fuel trims went lean, like they did before. starting to wonder if it is an exhaust leak that I can't find.

the catalytic converter diagnostic makes the fuel go rich, right?
 
Is it reading 16.4?

Leave it running and spray carb cleaner around the blower and core.

My bet is if it's sealed...the core is warped. And it's leaking that way. Or from vac lines. Or the EGR. Or the LIM.
 
it just seems really strange that as soon as I took the catalytic converter off and removed the rear o2 sensor that it went to 16.4. it could be a warped core, but I would be skeptical that it was the egr or vacuum lines. egr is gone, vacuum lines are all relatively new good quality silicone lines. it could be the lim, but like I said earlier, the timing is strange that it would start leaking.
 


If it's from an exhaust leak it's before or close to the upstream o2 but you'd probably hear it if it was bad enough to go to 16.4. Did you use all the rtv when you redid it? :D
 
I was only kidding lol.

I typically do an 1/8" bead and do NOT smush it with my finger. But if you did use too much maybe something is blocked by rtv.

Even if the core is warped shouldn't the rtv make up for that room?
 
I think I figured it out. I think initially the cat diagnostic was running, so I got that disabled, and in the process the tune I loaded didn't have the right injector skew for E85. so I changed the injector skew to 1.25 for E70. now all my fuel trims are within 5% of 0.

can you guys confirm that even if I added 25% more fuel for the E70, it would still run lean if there was a vacuum leak, or not run at all?
 


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