Hello all. I have Crawford HFCs installed with a NISMO exhaust and all is well with the combo (apart from a few install problems, sorted with spacers - see other threads). Now, here's the question...after the install, I did not reset the ECU and the combo did not throw a CEL: anyone actually measured what effect of installing HFCs is on the A/F? I mean, the "HF" in HFCs mean a less restrictive flow of the exhaust fumes, right? If no CEL shows, then the ECU still thinks all is well (or thereabout)...but I am pretty sure that A/F will be affected. My question is by how much...

 

you should have installed a wide band before and after. No way for us to know how much your A/F would change since all 350Z's take to Mods differently.

 

Anyone installed a wide band before and after by any chance? Do we know for sure the ECU hasn't gone into safe mode without throwing a CEL?

 

You will not throw one with HFC's only some models with throw it when the run Test pipes.

 

There are 2 subjects to address:

a. SES light because of excessive emissions? High-flow catalytic converters are designed to pass emission tests; therefore you should have no SES because of emission problems.

b. Do mods such as high-flow catalytic converters change the air:fuel ratio and how much? Yes the air:fuel ratio has been altered. And no I don't have the faintest idea how much.

 

Thanks david, that sums up what I think and I am trying to find an amswer to your b.