CEL and hard downshift to 1st(AT)
 

I made a muffler delete just as Berk's was made. Sounded great but he drone started to get to me. So I put a resonator in the middle between the two tips similar to Work's exhale AB-R exhaust. After I left the shop it was fine and everything sounded perfect barely any drone. By now the next day after install I have a CEL and when I downshift from 2nd to 1st its like a small jerk (Automatic transmission). This happened before, when I put in a K&N drop in filter but the symptoms were right away, But went away the next day. Any ideas on whats going on? I barely have 6000 miles.

Did you try pulling the code?

I would've but don't have a device or anything to pull it.

Just don't initiate a downshift to 1st unless you're moving above 20 mph

Its whenever I come to a stop under (10-15 ) mph like a stop sign or a light.

Well...

neither a drop in filter or catback exhaust changes should cause cel code. unless something was damaged or dislodged during install ie maf sensor or hoses causing air leak or connections , O2 sensors are miles away from catback.

you need to get the code it may be totally unrelated to your mods. but car should not be getting cel light, put it back to stock tak it back to dealer

But wouldn't the CEL go on right after the install of the resonated muffler delete? Not a day later?

This is a useless downshift. Let the tranny and TQ converter do it for you with less jerkiness.

-fellow AT driver

Sent from my OnePlus One

Why are ppl trying to downshift into 1st is beyond my....

I'm not downshifting it, the transmission downshifts it.... I'm not using the manual mode( or whatever the thing is called). When I approach a stop around 5-10 it'll go into 1st I'm assuming and I feel that jerk

Update its 2nd gear my bad

not necessarily for example the cat efficiency cel code P0420 can take a week to appear as the ecu compares reading from the two 02 to determine if cat is working to spec. Maf cels can be like that as well its got to be outside certain limits for a period of time.

it may also be a transmission code, or cam actuator code who knows but best to get it sorted before any damage done its under warantee take it to dealer (remove your mods first)

So unbolt my muffler delete put OEM back and should I take out the k&n filter or just leave it