The downpipe will be a direct bolt in. IDK if it's the same for your car as it is ours, but the new high-flow catalytic converter may throw a code (P0420). But you can just get a sim or a PCM for that.

 

are you still running a mass air flow sensor on the car after the swap? that will also affect the fuel mix if it isnt the right one/not performing right aney affect the miss fire in a way telling the injector to give/lean that piticular cylender thats what happend to mine. did every thing you did checking every thing but that. also the nock sensor as well both went on mine to make a multiple miss fire down to one and now gone.

 

hmm i could look into that..i wouldn't know how to test something like that though. i'm pretty sure it is the original MAF that came with the lower compression LTZ 3.8 (monte carlo 3.8) vs. the higher compression motor I have now 3.8 from a bonneville SSE.

 

I suppose I can find out the part number of the mas air flow on a lumina vs bonneville!

 

dont be supprised it will be around 110 to 240. the one i found for mine that is a better option is about 249 ordered from jeggs. mine is a high flow one that i fond jeggs has for my motor the hunny comb design for my model i found out has a lot of problems even with coming from the dealer. i found one for your motor at jeggs and it is 240 it should help out a whole lot with performance and help clear up the code. i hop the price didnt shock you?

 

dont forget to check the coil's pack one more time. i had to replace them as well after the mass air flow sensor was replaced. it was making one and two cylenders miss fire befor replacing the mass air flow meeter. and the coil packs never ran right afterwards so dont be shocked. do the air flow meter first then dont be supprised about the coil pack. also make a extra ground for your motor

 

man these cars are a little more complicated than my OBD1 honda that is for sure lol. anyway, 240 isn't bad for a high performance cat. cats are expensive in general lol..thanks for the info man.

 

so do u think the fuel pump is fine? it is just my cat being clogged that may cause my car to kill every once in awhile? cuz my car starts again right after it kills and the fuel pump sounds like it priming fine.

 

i was refering to the mas air flow meter the cat is about 190-210 befor shipping

 

ok thanks..still looking into this.