All MotorAll Motor Advanced Performance. Talk about Engine Swaps, Internal Engine work. Not your basic Y pipe and Intake Information.
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I've tried to look for opinions to find out the pros and cons of each, but have come up short, so I'm turning to you guys for input here.
For VQ header installs, I've seen that one camp recommends O2 sims in place of the downstream O2s while the other says to extend and bung the O2 sensors behind the main cat. Is one method better than the other for performance, durability, or emissions test purposes for whatever reason?
Here's what I found:
O2 Sims
Shorter install time (lower labor costs for those not doing it themselves)
No hassle with soldering and wiring
No need for welding new bungs onto the b-pipe
Less likely to have wire resistance matching issues when non-compatible gauge wires are used
Possibility of sim failure (seems to happen occassionally)
Downstream O2s just sitting under the hood
O2 Extension
More effort and time required for install
"Appears" less sketchy for emissions testing
It seems to me that O2 sims are the way to go, yet some people still prefer extending the sensors. Why is that?
Btw, if this is too elementary of a question to be in this forum, just let me know via flaming or sarcasm and I'll delete it and move it to the 5th Gen forum.
This is my take since I spliced into the wiring harness right BEFORE the o2 sensor harness (since the o2 sensor wires themselves are hard to solder)
The only bad thing I can see is that if I ever need to revert back to stock, it will not be a fun job de-soldering and reattaching all the stock wiring
The only bad thing I can see is that if I ever need to revert back to stock, it will not be a fun job de-soldering and reattaching all the stock wiring
Thanks Larry, although I'd assume that this would apply in both cases because if one extended the O2s, they'd have a hard time hiding/securing 3-4 feet of extra wiring if it wasn't reverted.
I'll assume you're asking b/c you will be doing a header install....IIRC, packetattack just had bungs welded in and was able to use his stock O2 sensors; try PMing him and see what he says.
i had mine extended because SR had access to welding equitment. i think the biggest factor would be your emissions testing. do they do a complete visual inspection? charlotte is pretty lax about visual and i have passed with both the simulator and the secondaries extended.
there is no performance difference since secondaries do not affect a/f and therefore do not affect power, mileage, etc. if you do the simulator just make sure the heater wire is left intact so you wont throw that code. the only issue i had with my secondaries extended was a wire fell out of the butt connector and threw a heater code. easily solved once it was discovered.
Thanks Larry, although I'd assume that this would apply in both cases because if one extended the O2s, they'd have a hard time hiding/securing 3-4 feet of extra wiring if it wasn't reverted.
I was thinking that if I had to extend my o2 sensor, I would purchase a new one and extend the wires, therefore I can just plug and unplug back and forth between the two
sloppymax brings up two good points also: emissions testing and availability of a welder on hand
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I was thinking that if I had to extend my o2 sensor, I would purchase a new one and extend the wires, therefore I can just plug and unplug back and forth between the two
Yeah, that's a good idea. I planned to do exactly that when I had a y-pipe since I had to extend my B2S2 by a foot or so (apparently you can pop the clips out and it'll reach, but I went the cut, extend, and solder route anyways). I never did it and now the excess slack is just zip-tied somewhere down there.
Quote:
Originally Posted by Larrio
sloppymax brings up two good points also: emissions testing and availability of a welder on hand
As far as I know, there isn't a visual inspection in VA so either way it shouldn't matter for me...
Anyways, so far it seems that people just pick whichever method is easier/more convenient at the time of install and the edge that the O2 sim route has over extending the O2s is that its an easier install and not that its a "better" method.
removing the rear O2's altogether gets wrid of physical restrictions where they would be welded on in the B-pipe, and of course it also saves you 2lbs, maybe. but you would have to use resistors to cancel out the heater circuit codes in the ECU.
Hey Joel. I got your msg last night a little too late. But to let you know, I actually rewired all my o2 sensors. I had the intention of possibly going back to stock, but if i had to do it over again, i'd do the o2 simulator. It just easier to deal with and i still get the o2 check engine light every once in awhile for the rear o2s.... So that's my 2 cents. The rewiring of the o2 wasnt too bad, and putting in a bung for the o2 was no prob at all.
Not a huge concern, however IIRC per the FSM, if one of the primary 02 fails or more importantly if the performance of the primary 02s degrade, the ECU will default to use the rears as a backup. This of course would cause a CEL and hopefully you'd quickly replace the bad front 02s, however I wonder what would happen when the ECU relies on the simulated 02 signal to calculate fuel trim. Also, those that always have a CEL wouldn't know there was a problem until they checked the codes.
Personally, I'll be extending the rear 02s vs. running a sim.
How about this? I just did a header install and planned to use a sim. It didn't come arrive in time so I did the install expecting to get a code till the sim arrived.
I left the o2 harnesses plugged in, bunched up the wire with the sensors and ziptied it to the radiator hose. It's been 5 full days with no sensors and no sim. The car hasn't thrown a code yet. Do I even need the sim?
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I'm starting to get pissed off at my o2 sim...the light is still blinking but I started to get more codes once again....about 1 month ago I got codes for my rear o2s but the problem went away by itself...I never actually tested the o2 sim like larrio told me awhile back....well now a month later, the codes started coming back again....I'm gonna keep clearing them and see if they come back...if they do...then I'mma check if the sim is running the correct voltage...if not, then I'mma just buy a new one cuz mine took a crap...
I wonder what would happen when the ECU relies on the simulated 02 signal to calculate fuel trim.
I thought about this a bit... so I know the ECU will try to maintain stoichiometric somehow during closed loop.... now if the signal from the sim is constant and the primaries are dead, I would think that the ECU would maintain one constant injector pulse width because the signal is unchanging, and this would lead to a constant rich or lean condition (or stoich) depending on the signal voltage from the sim (which I should go figure out from the FSM: what voltage range the secondaries should be operating within).
I think the only time you would need to worry about this is if both primary O2 sensors went and the MAF blew. But then you would have far worse things to worry about.
I think the only time you would need to worry about this is if both primary O2 sensors went and the MAF blew. But then you would have far worse things to worry about.
I agree, it was just more of a learning exercise for me.
Does anyone have a picture of the O2 sensors extended in the b-pipe? Will doing that affect performance at well? Might be a dumb question but I am not knowledgeable in the area.
No, it won't affect performance. During closed-loop driving, ie low throttle, the ECU only uses the FRONT 02s. During open-loop driving, ie high throttle >40% to WOT, the ECU ignores 02 feedback.
No, it won't affect performance. During closed-loop driving, ie low throttle, the ECU only uses the FRONT 02s. During open-loop driving, ie high throttle >40% to WOT, the ECU ignores 02 feedback.
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