Northernexposure

Here's the details...
2013 F150 STX 2wd reg cab short box with a 5.0
This past weekend I removed the exhaust and installed a single in single out exhaust that exits in front of the rear tire. I used a dynomax superflow welded stainless muffler, dynomax stainless intermediate pipe and made the tail pipe from a mandrel bend u-bend (all 3' diameter).
Problem is... Now the engine kinda went flat. Dropped enough power that it's noticable. Also, the engine idles extremely low now (around the 450 - 500rpm mark). No welding was done on the truck... it was all lined up and marked with witness marks and welded on the bench.
Is it possible the the system doesn't have enough back pressure for the engine to run properly?
My only idea is that I now need a tuner with a custom tune to correct for what I've done... something I was trying to avoid while under warranty but was looking forward to when it was off warranty.
Long story short... help?!?!

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dieselhunter44

Unhook the battery terminals for an hour then reconnect. But an exhaust shouldn't hurt your performance or make the truck run badly

Blackpony

Unhook the negative terminal on the battery and turn the headlight switch to the on position. Let sit for 10 minutes the reconnect and drive the truck. It may take 50 or so miles for the ecm to go through all of its checks, but this should help.

RLXXI

3" is too big for stock, after you reset the system with batt disconnect you will either want to reduce the diameter of the pipe or get a tuner for it. You also affected it by shortening the pipe those few feet. Put it back behind the rear tire or you will mess up the finish on that wheel.


It needs a little more back pressure than that 3" pipe will allow.


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Northernexposure

OK, I get the part about resetting the computer by unhooking the battery. Makes sense and honestly, it didn't even cross my mind.
Now, the part about the diameter, honestly, and this is gonna be hard to describe... the exhaust IS three inch... but the intermediate pipe starts at about 2 1/2" where it bolts to the collector. Theoretically, giving it an initial diameter of 2 1/2".
As far as locating it behind the tire... not an option. I realize that the exhaust has some "nasties" with it that can/will effect the finish on the wheel. No biggie.... they make thousands upon thousands of cans of paint every day. The reason it's not an option... because it's different! Seems everyone has these nice systems that exit behind the rear wheel(s) with the shiny tips. Yes, it's a nice look... but it's not my kinda nice. All through life I've walked to the beat of a different drum and I'm not gonna stop now.
I do thank everyone for their opinions and helpful notes for my problem.
I'm gonna try the unplug and reset thing and if that doesn't work I'll plot my next step.
Thanks again guys!

BlueFlameMetallicFX4

You have to jump the battery cables (unhooked from battery) also...this will clear everything in the ECM.

03king

A single 3 inch pipe is not too big, don't let anyone convince you otherwise. The mustang 5.0 comes with dual 2.25 at its smallest point. And dual 2.25 flows more than a single 3.

Gonkey

They are running dual 3 inch on aftermarket mustang systems.

papa tiger

Reset N relearn.

ns_redneck

yeah try the reset, it says in the magnaflow instructions to unhok the battery. i have installed a few of the magnaflow kits and they all idel lower once installed, but they don't lose any power. i never did one the same as yours but it shouldn't be any different. i did a muffler and resonator delete on one and it never had a problem either.