CEL after Doug Thorley Install + Way too loud. Help!

After DTLT install on 07 4.0L I keep throwing a CEL with code P0402. O2 sims also installed but still throwing CEL code P0402. The code translation is: Excessive EGR flow.

My question is this, even though I keep clearing the code with my scanguage, will the ECU eventually learn that the new EGR flow is normal and adjust itself accordingly?

Also, running DTLT's, custom y-pipe that deleted the secondary cats and a Dynomax Straight thru 2 into 1, 18" muffler. It's sounds like I'm running it with open headers. You can litteraly roll a marble down the header and it would drop out the muffler without stopping. Way to f'n loud and tinny sounding. Any suggestions on another muffler that may give a little quieter, lower rumble and not sound so raspy. Thanks all.

 

which y pipe are you running? you might want to add a second mufller to your cat back.

 

Or a resonator.

 

Custom y-pipe that deleted the secondary cats and tucked up a little further in front of the transfer case to keep the whole exhaust system above the frame rails. So there are no cats anywhere in the system. Headers to straight 2 3/4 y-pipe to muffler to tailpipe ending before rear axle. I think I went too far.
I'm just going to have to try a different muffler, flowmaster or something to quiet it down. If it were 20% quieter, it would be perfect.

 

and/or,,, is your O2 sim correctly installed?

I have the APR X-1 controller, it does not read the rear sensors therefore no codes... But, I once forgot to plug back in the rear sensors and threw a similar code.

Try rechecking all your conections, then disconnect the neg battery cable for 10-30 min. Re-attatch, and see if CEL pops up again 50-100 mile down the line.

As far as Sound, you should've known that all CATs removed would = LOUD!!!

j/k... But yeah try the second muffler or resonator. I opted to go back to stock Y-pipe. But now that im Boosted, im looking at runing a test pipe again; and will be running an 18" resonator in front of the Banks muffler.

Good luck, and congrats on the headers...

 

I had this issue as well with same headers and y pipe. One of the 02 sensors on the headers wasn't plugged in well so check everything. I also went back to stock headers and y pipe. Sound and smell made me go back to stock.

 

Thanks all for the responses. Putting resonator(s) on Monday. That should do the trick.

Btw..the code i was throwing was P0420...catalyst problem, not P0402...EGR flow...my bad. I'll try unhooking the batt for 30 mins and see how it goes. At least it's not another issue. I sort of expected the CEL might show up. Thanks again.