Engine performance wrt catalytic converter.

[Anotrin]

Recently did an engine swap on a locak almera frim qg16 ti qg 18. Was having tranny issues so I swapped engine as well. Complete rewire was done etc. Thr qg18 comes with 2 oxy sensors one at the front and one at rear.. my original set up never had oxy sensors or a cat coverter. I initially I ran the qg18 eith my original exhaust. However to get rid of the error lights I needed to install the 18 sensors and muffler set up. A chop n weld was done to the 18 manifold to my stock exhaust. Having done that I have noticed a significant drop in engine performance. Everything works but the pep that was there before the exhaust change is now gone. Acceleration is poor. The electrician has cleared of any codes and deems all parts functional.

Im not sure what would be causing this. The only difference is either a shoddy muffler join or the cat conveter that is built in to the stock 18 exhaust. Does a cat reduce performance ? Who can I go to to analyze this? Any assistance is much appreciated.

[skylinechild]

Recently did an engine swap on a locak almera frim qg16 ti qg 18. Was having tranny issues so I swapped engine as well. Complete rewire was done etc. Thr qg18 comes with 2 oxy sensors one at the front and one at rear.. my original set up never had oxy sensors or a cat coverter. I initially I ran the qg18 eith my original exhaust. However to get rid of the error lights I needed to install the 18 sensors and muffler set up. A chop n weld was done to the 18 manifold to my stock exhaust. Having done that I have noticed a significant drop in engine performance. Everything works but the pep that was there before the exhaust change is now gone. Acceleration is poor. The electrician has cleared of any codes and deems all parts functional.

Im not sure what would be causing this. The only difference is either a shoddy muffler join or the cat converter that is built in to the stock 18 exhaust. Does a cat reduce performance ? Who can I go to to analyze this? Any assistance is much appreciated.

the catalytic converter is meant to convert carbon monoxide to carbon dioxide and other harmful substances to less harmful stuff.

having one will give you a slight performance drop as its essentially a restriction however the engine designers take this into consideration when designing and building the engine.

if the catalytic converter is bad..now theres another issue.
you can remove the cat converter temporarily by using a test pipe - and see if you feel any difference.
also the Qg 16 exhaust piping may be different...as opposed to QG18...one may be 1.25 inches and the other may be 1.5...

[X_Factor]

the qg16 has the cat converter, its located on the exhaust manifold, similar to ga15

muffler shops usually charge about 150 to take out the manifold type..simply using steel rod to break up the charcoal packing and take it all out

If the muffler join is restrictive it may cause a drop in performance as well

[Anotrin]

Never saw thr converter on my qg16. I didn't even have o2 sensors. The qg18 cat is pretty visible.
The welding I admit looks shoddy. Any recommended muffler guys I can check to redo the welding before I break up the cat?

[X_Factor]

well on the 16 you cant see it, its located inside the exhaust manifold
im from up uwi side and the muffler shop i usually go to is in tacarigua
not sure if u wanna drive up soo far
just go by a shop who has a pipe bender so they can make whatever they need
rather than someone who does not and they will just give u the ratch weld up

IF the qg18 cat is visible then they change that whole piece of exhaust
If you plant to keep the vehicle for some time in the future why not try and source some headers since ur doing exhaust work ?

[X_Factor]

check this out
http://www.amazon.com/Nissan-Sentra-Des ... st+headers

http://www.amazon.com/Nissan-Polished-S ... R64Y92S9PD


user says it works on the qg18 with spot for egr

[Anotrin]

Was actually looking at that but not sure how it will fit up in the almera. will ask around and see if anyone used these on their car. Also a new bung may have to be welded for the second o2 sensor right? Thanks alot for the help!