Interesting findings with exhaust mods and tuning

[Detroiter]

Originally Posted by guybo

3" catback on a NA 2.0L car? That will kill torque right there. Now that I reread the OP, Deleting the FP cat without a tune may have killed some power. Still, it's odd to me that it performed so much worse.

As for the CEL P0420, the reason it's bad is that the car may not run some self diagnostics when it sees a CEL. You can in theory have hidden issues come up but the ECU isn't running those tests. I'm not sure exactly what tests that'd be but there are techs familiar with techstream in this forum who might know

There have been dyno charts showing no change or even a slight gain with my 3.0in catback just like any other catback on our cars. It does nothing but change the noise. As for the catless FP I can guarantee it has little to no effect on power and torque untuned. I was stating that there is no NEED to get a tune with even a full exhaust system on our cars. Yes it will get you the power and make it run better but there is nothing damaging being done let alone causing it to run that lean.

[steve99]

Originally Posted by guybo

3" catback on a NA 2.0L car? That will kill torque right there. Now that I reread the OP, Deleting the FP cat without a tune may have killed some power. Still, it's odd to me that it performed so much worse.

As for the CEL P0420, the reason it's bad is that the car may not run some self diagnostics when it sees a CEL. You can in theory have hidden issues come up but the ECU isn't running those tests. I'm not sure exactly what tests that'd be but there are techs familiar with techstream in this forum who might know

you will only get the P0420 CEL if you change to cattless header.
Car will light CEL and cruise control is disabled. Other than that noting bad will happen. Having the constant CEL does mask other issues though.


disabling P0420 code in tune just stops the CEL for that particular code and it stops ECU taking action on that code ie disabling cruise control.


however disabling p0420 code will not make the ecu pass the readiness checks it just disables CEl for that code. Readyness checks require data from front and rear 02 sensors, and the ecu wants to see certain patterns in the data from the sensors before. with no cat you will generally fail readiness checks for cat converter and emissions.


no current tune software forces readness check pass

[Joeyb860]

So I have uel cat less headers and cat less front pipe with stage 2 + oft tune but did not change my intake do I need to do anything to the mas sensor? Would I get any more if I change to a trd cold air intake? I was not going to change it because when the 36,000 mile warranty is up I was going to turbo it so didn't want to waste the money on cold air intake. Im going to e 85 this weekend and have seen threads about scaling the maf sensor before going to e 85 any in put on this topic. Thanks.

[NRXRaptor]

Originally Posted by Joeyb860

So I have uel cat less headers and cat less front pipe with stage 2 + oft tune but did not change my intake do I need to do anything to the mas sensor? Would I get any more if I change to a trd cold air intake? I was not going to change it because when the 36,000 mile warranty is up I was going to turbo it so didn't want to waste the money on cold air intake. Im going to e 85 this weekend and have seen threads about scaling the maf sensor before going to e 85 any in put on this topic. Thanks.

I'd just email Shiv on the OFT website. I had questions about my setup and he answered them. He'd know better than anyone on here