Smog pump removal mess with stock O2 sensors?

[94Blue302GT]

Basically, I don't have the money for a chip or tuner at the moment, but I would like to get rid of my Smog pump. I have the tube gone that goes down behind the cats (well, it's on O/R Hpipe from summit) and I was going to get rid of the pump and injection to the heads all together. Won't this mess with the computers o2 sensors? I have a third sensor that reads the ratio, a one wire that goes to my gauge, and it stays where it is supposed to most of the time, jumps up a bit when i shift and get on it, but then a lot of times while cruizing it dips all the way down and back up, like the regular light show most of us know about! I'm thinking it's due to the air injection, partly the reason i was going to get rid of it. I was thinking it might be the gauge too, but since i got rid of the one pipe (and sealed up my leaky exhuast) it has improved a LOT. So, will it mess with my computer or no? I also have a AFPR to tune the fuel if needed.
Lee

 

[stackz]

but then a lot of times while cruizing it dips all the way down and back up, like the regular light show most of us know about!

your a/f gauge is working properly. the light show is typical when cruising due to the injector pulsing the ecu does for economy purposes....that and if it held the injectors open during cruising they'd overheat and fail

they are afterall nothing more than little gas-resistant reostats.

as for smog pump, taking it off wont hurt the o2 sensors any more than taking the cats off. If you took the smog pump off and left the cats on however, you'd soon have nicely clogged cats.

 

[smokediver27]

Not an expert at all here, but seems that the O2 sensors are before the cats (I think), so getting rid of smog pump should not change a thing there. I've done my smog and EGR with no issues other than the car runs slightly cooler now at highway speed.

I would lean towards the theory that the O2 levels should stay the same, since you have the Summit H-Pipe (same as me), the smog really isnt accomplishing anything anyways, O2 concentration is measured immediately after exhaust leaves the headers.

Get rid of it and enjoy the extra space on the passenger side of the block....

 

[94Blue302GT]

your a/f gauge is working properly. the light show is typical when cruising due to the injector pulsing the ecu does for economy purposes....that and if it held the injectors open during cruising they'd overheat and fail

they are afterall nothing more than little gas-resistant reostats.
...

So the light show i'm getting is due to the injector pulsing? I'm afraid I just don't understand how that works. I know they aren't going to be open the whole time, obviosly, but I figured since it measures the exhaust fumes, wouldn't THAT be what stays the same? Remember, this is a STAND ALONE SYSTEM! I think you might be refering to hooking it up to the other 2 O2 sensors.... NO, this is a third one. If what you say is the case, then no O2 sensor would ever be able to get a constant reading of the A/F ratio?

 

[stackz]

So the light show i'm getting is due to the injector pulsing? I'm afraid I just don't understand how that works. I know they aren't going to be open the whole time, obviosly, but I figured since it measures the exhaust fumes, wouldn't THAT be what stays the same? Remember, this is a STAND ALONE SYSTEM! I think you might be refering to hooking it up to the other 2 O2 sensors.... NO, this is a third one. If what you say is the case, then no O2 sensor would ever be able to get a constant reading of the A/F ratio?

a/f ratio under load is the one that is most necessary. that's where the best chance of breaking something occurs.

are you meaning that you've got a wideband o2 sensor and gauge set? or just something like an autometer pro-comp a/f gauge and you gave it it's own o2 sensor? either way you will see fluctuations while at cruise speeds even with a stand-alone setup for the same reason that when not under load, the system will greatly reduce the injector pulses as injectors just aren't OPEN all the time. you will fry injectors if they are continually in closed loop operation.

hard to explain why it dances at constant cruise speed in a short way but here goes anyway haha...

the engine management whether performance or oem still has to keep the car from blowing up. fuel maps and ignition maps might be fully tweekable for sure but they are still built on the same base as oem units. they are programmed to pulse the injectors unless deemed otherwise to keep the car running safely. Under load this requires that the injectors be full open then they will be full open. you dont need that much fuel at part throttle though....would probably flood the car out anyway to dump that much at part throttle. So instead of full open, it pulses the injectors less or more per revolution to keep the engine running at the same rpm (say if cruise is on) this is affected by the a/f ratio also. if it's dumping more fuel to keep it at that rpm dictated by TPS sensor then you'll see the a/f gauge naturally dance up to the rich side....then as it realizes it doesn't need that much fuel to stay at that rpm...it'll start cutting back on the pulse lengths and of course....less fuel will lean out and suddenly the a/f dances back down to lean...then the ecu realizes it needs more fuel to maintain rpm...adds more length to injector pulse....a/f dances back up to rich again...rinse/repeat.

the exhaust gasses are directly affected by this continual richening/leaning process...and it's happening at 2500rpm which will change the readings very rapidly and thus you get the dancing light.

 

[94Blue302GT]

hey, thanks!!! That actually makes sense (for the most part). So, when i get on the throttle, if the light is slightly on the rich side (i have 4 lights for lean, 4 for ideal, and 4 for rich) then i'm probably fine, right? At cruising it pulses up to the "richest" ideal bar and then goes back down. For just cold air and H pipe and timing bumped i should be fine, right?

 

[stackz]

hey, thanks!!! That actually makes sense (for the most part). So, when i get on the throttle, if the light is slightly on the rich side (i have 4 lights for lean, 4 for ideal, and 4 for rich) then i'm probably fine, right? At cruising it pulses up to the "richest" ideal bar and then goes back down. For just cold air and H pipe and timing bumped i should be fine, right?

yes, as long as it's in the green (rich) when you hit the throttle, then you're fine. You'll need to start worrying if you mash the gas pedal and it's in yellow (stoic) area and you'll want to get off the gas fast if it's in the red (lean) area.

You dont honestly need to worry about this much if you're N/A but if you use forced induction (supercharger or turbocharger) or nitrous then that's when you need to worry because these systems and a lean condition will skyrocket the egt's and you'll melt parts or blow up all together (the hotter it gets the easier it is to detonate even with perfect timing etc, especially if the cam has lots of overlap).

You can actually gain a little power in a N/A car by running a little leaner under load and not hurt anything but you want at least 12:1 a/f when F/I. I normally run 11:1-10:1 when I auto-x with my civic at road atlanta for example.