Running Lean After Exhaust+Test Pipe

[tec_41]

Does this make sense? Yesterday my wideband was reading good numbers, 14-15 at idle...Today I installed a 2.5" catback and a test pipe and the numbers are noticably higher: 16 at idle, peaks at 17-18 while cruising. Under WOT they're decent, but is this normal?

 

[delta448]

Your profile needs updated. Are you tuning with a speed density setup? Improvements in VE that are not accounted for with fuel tuning changes will show up as lean spots in a SD tune.

 

[bullettdsm]

Does this make sense? Yesterday my wideband was reading good numbers, 14-15 at idle...Today I installed a 2.5" catback and a test pipe and the numbers are noticably higher: 16 at idle, peaks at 17-18 while cruising. Under WOT they're decent, but is this normal?

Why yes, yes it is. One of the reasons that the 4g63 guys tune after putting on a bigger exhaust....because they have to, . You have effectively removed a blockage area for your air flow so it is allowing more air to flow and needing more fuel.

Now, I'm thinking that you are still on the stock ECU (no MSnS). If that's the case then just watch them for a little bit. They should start going back toward stoich as the ECU adjusts.

MB

 

[tec_41]

Thanks guys, I appreciate it! I have noticed the numbers slowly starting to drop, idle is back where it should be.

I'll update my profile as well