o2 sensors on 4-1 header

[Strugglebucket]

as some of you know i'm running an s&s 4-1 header. i'm using two oxygen sensors but because it's a 4-1 header the bungs are each on an individual primary vs. the stock manifold's 4-2-1 setup where one sensor is at the merge of the 1 and 4 primaries and the other is at the merge of the 2 and 3. the car runs good but i've been getting a code 1 when i take it on the freeway.

any ideas on how i could fix this?

[white ricer]

thats wierd my 89 has the two right new to eachother. You could probably just drill and tap bungs where ever on the header. your car runs fine without them hooked up so i doubt the location of the sensors will effect codes.
my .02

[Strugglebucket]

what i'm getting at is that the o2 sensors are seeing half as much o2 as they used to. i haven't checked the voltage yet but i'm guessing it will be low.

[Strugglebucket]

the header's great except for trying to use anything emmission's related with it. what's weird is i gained a massive amount of low end, contrary to what most people expect from a 4-1.

[A20A1]

ahh, you have 666 posts.

Well it's not that 4-1 is stictly top end... what it usually is, is narrower rpm gains but bigger. Where as the 4-2-1 is broader rpm gains with maybe not as high of a gain. Both headers will see gains over the rpm range but the curve is different. What is the rest of your exhaust like?

[TheWatcher]

the header's great except for trying to use anything emmission's related with it.

Translation please? IOW, could you clarify exactly what you mean by relating to emissions.

I read earlier threads that someone had problems lining up the EGR, and someone else had no problems w/ the EGR lining up at all. Could you tell me if you had any problems w/ the EGR.

TIA.

Peace.

[Strugglebucket]

Translation please? IOW, could you clarify exactly what you mean by relating to emissions.
I read earlier threads that someone had problems lining up the EGR, and someone else had no problems w/ the EGR lining up at all. Could you tell me if you had any problems w/ the EGR.
TIA.
Peace.

the egr wouldn't work at all. totally wrong angle on the bung, also wrong sized fitting. i found a fitting from a geo metro that fit, but then i still couldn't get it to line up and my attempts at welding that thin-ass stainless egr piping were a dismal failure. and now it seems i'm have problems getting the stock o2 sensors not to throw a code.

What is the rest of your exhaust like?

i had a 10'' section of flex added to the downpipe because the socket wasn't flexing enough for my liking (i was afraid i was going to break something). from there i have one of those straight-through ebay cats and then a generic resonator to 2¼'' piping ending with a dynomax super turbo muffler with a straight piece of stainless pipe for a tip.

[Strugglebucket]

hmm. i was thinking about it, and i'm almost sure my promlem is from the o2 sensors only seeing exhaust from a single primary. i know it doesn't make a difference in the actual lean/rich composition of the exhaust, but intsead of getting two exhaust pulses per engine cycle it's only getting one. so at steady rpms after a while the ecu thinks the voltage is fluctuating too much. does that make sense, or do the o2 sensors not respond quickly enough for that to make a difference?

BTW, i drove it on the freeway to work today and the code never came on. then again, i was accelerating and decelerating a lot.

[TheWatcher]

the egr wouldn't work at all. totally wrong angle on the bung, also wrong sized fitting. i found a fitting from a geo metro that fit, but then i still couldn't get it to line up and my attempts at welding that thin-ass stainless egr piping were a dismal failure. and now it seems i'm have problems getting the stock o2 sensors not to throw a code.
i had a 10'' section of flex added to the downpipe because the socket wasn't flexing enough for my liking (i was afraid i was going to break something). from there i have one of those straight-through ebay cats and then a generic resonator to 2¼'' piping ending with a dynomax super turbo muffler with a straight piece of stainless pipe for a tip.

Thanks for the 411.

No emissions here YET. But I believe money was allocated by the legislature to do some preliminary work that might eventually lead to emissions here. Good to know.

Peace.

Peace.

[Strugglebucket]

no one's helping me with my questions, so i'll ask another one:

do our ecu's modify fuel from input from the o2 sensors full-time or only under certain conditions?

[A20A1]

If your ignition system; plug, wires, coil, cap, rotor... are having misfires it will give a false reading to the O2 sensor.

[Strugglebucket]

no misfires, all the parts are good. only thing ignition related would be my distributor being slightly retarded due to it being a rebuilt piece of crap.

[Oldblueaccord]

no one's helping me with my questions, so i'll ask another one:
do our ecu's modify fuel from input from the o2 sensors full-time or only under certain conditions?

well i can take a crack at this part. I think our cars look at the O2 sensor from off idle to 5500 rpms. After that I think the car reverts back to WOT preprogramed maps and ignores the sensors reading. I wonder how much it really looks at the o2 sensor because there 1. very inacurate 2. if you use a fuel modifier like an SFC you can go somewhat richer and not see a problem 3. (part of 2) you can turn up your fuel pressure or plug the vacuum line and not see a code also.

And it is my opinion that the car does not look at the o2 sensors at idle.

As far as your problem the only thing I can think of is most headers I have seen only have a bung in the collector not in the pipes.or like i am looking at buying the innova wideband O2 and the want you to weld the bung at the collector about 3 inches from the merge.


wp

[Strugglebucket]

so you think they're rpm dependant? i was thinking they only ran in closed-loop operation and weren't used during WOT and hard acceleration/ decceleration. what bugs me is no one really knows very much about how our ecu operates. it would be nice to know what sensors are active when and how they interact with eachother under what circumstances, what the tables look like, etc.

i know what you're saying about the o2 bungs being in a wierd place. they are about where the collector would be, if it were a 4-2-1 header.

what i'm wondering is if the o2 sensors are very inacurate, they must be giving a really lean reading to the ecu for it to throw a code. i'm going to see what kind of voltage they're putting out this weekend. the exhaust smells kind of rich, but i think that's more because i'm running an empty cat. so far any time i look at the plugs they come out clean as a whistle, making me think that i may actually be running a little lean. which baffles me.

if i reset the code, it takes about 10 minutes of driving at steady throttle for the check engine light to come on. the instant the light comes on the car surges a bit, like it got a little more power all of a sudden. even if i don't reset the code, the light won't be on if i stop the car and restart it. it will take the same 10 minutes at constant throttle to come back on. if i manipulate the throttle with any regularity while i'm driving i never get the code.

[Oldblueaccord]

I vote your lean. if it codes out it goes rich.

Plug the fuel pressure regulator and see what it does. should richen things up a bit. Im wondering if there running to hot being too far up in the pipe. I dunno if the voltage will help last one I looked at the voltage jummped all over the place.

Can you check your pipes temp?. Hot is lean cold is rich. Need an IR gun over or close to a thousand degrees.


wp

[Strugglebucket]

i've got an fpr that i'm already running at 45psi, i could bump it up some more. i doubt it will help though, the fuel pump never keeps up with where i set it at anyway.

[Oldblueaccord]

i've got an fpr that i'm already running at 45psi, i could bump it up some more. i doubt it will help though, the fuel pump never keeps up with where i set it at anyway.

oh 45 psi already..... i wonder if the pump can handle that high or the injectors. One injector could be hanging open or going 100% like you said at steady throttle. Need bigger injectors if your needing that much fuel pressure.

I guess go with the basic see what a plug looks like again. Clean as a whistle means?? White is lean black is rich.

Im forgetting you engine setup.

wp

[Strugglebucket]

i tried bumping up the fuel pressure a little this weekend but it didn't make much of a difference. i'll see what i can come up with as far as a problem with an injector, that's a good idea.

the plugs look clean like they're brand new with barely a tiny bit of tan/white on the electrode. i'm running BPR7 ngk iridiums. my engine setup is a 256/272 cam with the head and stock intake ported and matched. tb bored to 59.5mm, homemade cai, msd sci (6 series), accel super stock coil. um, the header i already mentioned running to 2¼'' exhaust.

[Strugglebucket]

sorry, double post

[Strugglebucket]

what if i ran an o2 sensor on each primary? then i could wire #2 and #3 in parallel to one harness and #1 and #4 in parallel to the other harness. it would be pretty much the same as the stock setup as far as what the ecu sees. only problem is then i have to take the freakin header out again to get new bungs welded.

[Oldblueaccord]

i tried bumping up the fuel pressure a little this weekend but it didn't make much of a difference. i'll see what i can come up with as far as a problem with an injector, that's a good idea.
the plugs look clean like they're brand new with barely a tiny bit of tan/white on the electrode. i'm running BPR7 ngk iridiums. my engine setup is a 256/272 cam with the head and stock intake ported and matched. tb bored to 59.5mm, homemade cai, msd sci (6 series), accel super stock coil. um, the header i already mentioned running to 2¼'' exhaust.

Im reading I just dont have any good suggestions. But here's a few thoughts.

1. I wonder if the 45psi or mores is really doing anything

2. If you want to moniter your O2 sensors find the pin out on your ECU tap into them and use your meter "in cab" to see where your at. I really dont think youll see anything but it be worth a shot.

3. As far as more o2 sensors Im not sure if you really need that many. Im still thinking you want one in the collector. you should be able to drill that your self.If its SS header might be hard to weld up esp under the car. Im not sure how it be wired up.

4. http://www.innovatemotorsports.com/products/lm1.php

this is the wideband im looking at hopefully for Christmas. The thing your going thru proves to me at least how valuable a wide band could be. Otherwise its all guess

5. What ocatane are you running? does higher do anything for you at all? Wonder if the car runs lean/or pings at a certain rpm higher making it hard to hear. you generally cant hear a car ping at high rpm's .


wp

[Strugglebucket]

I wonder if the 45psi or mores is really doing anything

i doubt it.

i run 91 octane most of the time but it runs just as good on 89.
no pings that i can notice, but then my timing is set slightly more retarded than stock until i can find a good distributor.