So after the test pipe was installed on my car it threw a CEL due to the 2nd O2 sensor.

My question is would this cause the ECU to make my car run rich? It smells pretty bad out the exhaust now.

Thanks.

 

Well, i'm not an expert on this, but I would think that the reason your second O2 sensor is throwing a CEL is because you no longer have a cat. So obviously the second O2 sensor is gonna chime in and say "hey, the exhaust seems kind of dirty over here" because there is no longer a catalytic convertor cleaning the smog out of the exhaust. And as far as the exhaust smelling bad, same idea, theres no more cat cleaning the exhaust.... that would make sense to me, correct me if i'm wrong. Just puttin 2 and 2 together here.

You do know what a test pipe is right? Its just a straight through pipe that doesn't do anything to the exahust. IE doesn't do what the catalytic convertor does, which is clean the exhaust up a little, so it doesn't pollute as much.....

 

You can get a fooler for the o2 sensor for like $100.

 

Yeah I know but I'm getting terrible mpg and was just wondering if that was associated with having a test pipe.

 

your low end torque will probably suffer as a result of a test pipe because of less backpressure. that might cause you to get worse mpg if its a daily driver and i would guess you shift in the low rpm ranges the majority of the time.

 

with less torque in the low rpms... every time you press down on the gas pedal, you press down further(for the car to pick up faster). that causes you to waste more gas.

**all that aside, in the high end... it really picks up.

 

Hmmmm never thought of that, good point guys.

I'm sooo granny-shifting from now on...

 

i think u missed the point.... even if you granny shift, you are gonna get bad MPG. as long as you are driving around in the low RPM range, your miles per gallon is gonna suffer. may as well rev it up to v-tec everytime!

 

Ahh I gotcha now.

No VTACK here y0 :-(

 

=<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by kennyfsu &raquo;</TD></TR><TR><TD CLASS="quote">Ahh I gotcha now.

No VTACK here y0 :-(</TD></TR></TABLE>


someone should make a valve cover that says like "DOHC VTACK" cuz everyone says that...its sucha gr8 word though

 

maby your o2 sensor is bad, my friend, an idiot, took his cat off and let the sensor just dangle and he started geting worse mpg so he tested it and it was bad, but idk if this is your problem.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by b18tegra &raquo;</TD></TR><TR><TD CLASS="quote">maby your o2 sensor is bad, my friend, an idiot, took his cat off and let the sensor just dangle and he started geting worse mpg so he tested it and it was bad, but idk if this is your problem.</TD></TR></TABLE>

thats a good point... the O2 sensor, since it is throwing a CEL, might be causing the ECU to make you run rich, or run some other way that is not optimal. you might wanna check in to that.

 

well is your engine check lighht on? it sould come on if the o2 is bad, but sometimes not, i guess

 

Yeah the CEL is on and the O2 sensor works.

 

i have a test pipe and no o2 sensor what-so-ever and got 540km w. my last 10 gallons.

 

The reason your MPG's are down is b/c your CEL is on. When it is on it doesn't go into closed loop (running off O2 sensor to meter fuel). Instead, since the ECU is 'assuming' that there may be a problem with the engine, it runs it in safe mode, which is always rich, which is where all your fuel is going.

And yes the reason you're throwing the code (P0420 I'm guessing) is b/c you don't have a cat. You need to either get the 2ndary O2 simulator (where does one get those, BTW?) or you need to put your catalytic convertor back on, or you need to go to OBD1 which does not monitor cataylist efficiency.

WORD.

 

you could always get your car tuned with something like hondata or chrome, i believe both of them can bypass that code with their program.

plus if its not tuned, its a worthwhile thing to check into

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by kchungb17a &raquo;</TD></TR><TR><TD CLASS="quote">The reason your MPG's are down is b/c your CEL is on. When it is on it doesn't go into closed loop (running off O2 sensor to meter fuel). Instead, since the ECU is 'assuming' that there may be a problem with the engine, it runs it in safe mode, which is always rich, which is where all your fuel is going.</TD></TR></TABLE>

This is incorrect. A CEL for a secondary O2 is only indicating that there is a problem with the cat (in this case, it's missing). This will not affect the ECU's closed loop operation and the car will not be in "safe mode".

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by kchungb17a &raquo;</TD></TR><TR><TD CLASS="quote">You need to either get the 2ndary O2 simulator (where does one get those, BTW?) or you need to put your catalytic convertor back on, or you need to go to OBD1 which does not monitor cataylist efficiency.</TD></TR></TABLE>

It's not a tremendous issue if you don't mind staring at the CEL constantly. The main problem is that, since the CEL is always illuminated, you won't be alerted if the CEL is triggered for a different engine problem. Personally, I would suggest purchasing a quality high-flow cat such as the ones offered by SMSP.

 

i rode around for a yr with the CEL for secondary o2 sensor b/c of my high flow cat and then switched to a stock cat for smog and left it on for about 6months...didnt notice any differences in mpg or performance for the most part..