i had been having a problem at idle where my car was pumping out hydrocarbons like a gas pump. with no obvious answer I found, via a blowtorch, that due to the larger size pipe of my trueleo headers, combined with them not having the factory heatshielding(1 layer of wrap wasnt enough) the o2 sensor was cooling off during idle within a minute or two, forcing a very rich condition. i went to the parts store and grabed a denso 3 wire o2 sensor and wired it into a relay whcih gets switched by the wire that initilizes the fuel pump (pin A on the connector if i recall right).
Right away the idle stabilized to within 50 rpms and there was a noticable difference in engine note and smoothness. the hydrocarbon output was cut from 1200 to 500-600 and the co2 went from 8% to 11%. driving it is slightly crisper and quieter so i deam this mod a success. Should get even better results with the 7730 ecm.
Ill post the p/n when i get to work but basicly all the narrow band o2 sensors are the same

Did you install the O2 into the original bung? I had read it the original bung was too close to the exhaust manifolds and in turn would shorten it's life.

We haven't heard of idle problems, if others have ahd the same issues maybe that just didnt related them to headers? Glad you posted this info, we'll pass it on the customers and add somethign about it on our installation instructions.

BTW: With our Y pipe the 02 bong is about 1/2"-5/8" high and thus further from the pipe than the stock unit. If you look close at the Y pipe I made for use with stock or Sprint headers youcan see the bong.

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Trueleo.com/fiero.htm
RSpiderII@aol.com

i c a bung, no bong tho, unless its hiding behind the motor. Francias the location of the bUng on my ypipe is in the stock spot just angled around so i cant replace the o2 sensor without lifting the car, i know it was placed higher on the sub 87s. it makes sense that the larger diameter pipe could cool off the o2 too much at idle, i have some pieces of the stock 3.4 liter exhaust from the camero and it looks like they figured it out too and used double walled piping. wraping the pipe didnt produce a big difference whcih contributed to how long it took to figure out but eventually I narrowed it down to the o2 being too cold simply because everythign else was exactly the way it should have been to run right, yet it wasnt.

as for something damaging this setup the only thing i was worried about was thermal shock on the o2 sensor, modern cars pulse the heater circut and delay its activation to allow a natural buildup of heat before the heater circut engages. in my case as long as the key is on the heater is on, old volvos did this too and thats where i got the idea that it might just work. hopefully it lasts.

its super easy to install, if you can wire up a relay and install an o2 sensor youre good to go, heres the o2 sensor i used
Denso 234-3000

i also gotta say im pretty sure i blew my cat apart a while ago, hence my high hc count, 500ppm will not pass emissions in virginia but on the dyno the hcs drop to about 150ppm, add a new cat and it should be near 0. i am going to try and get this thing to put out zero hcs or at least 14%co2. that should save me some gas to not pump out so much without being burned. i cant wait to see what the 7730 can do ontop of this.

In my part of vingina they don't check emmisons! Spotsylvania

My modded 2.8 also has Trueleo headers. And I noticed that when idling for a minute or so, it will drop into open-loop mode. If I rev up the engine, or start driving it, the ECM will quickly return to closed-loop mode. The length of the primary pipes, combined with the sheer volume of the headers, may have something to do with that.

During the closed-loop to open-loop transitions, and vice versa, the idle sometimes will fluctuate a bit. Although, I have a feeling the ECM programming may have something to do with the idle fluctuations. My ECM still hasn't been fine-tuned for this engine.

In any case, I plan to install a heated wideband O₂ sensor in the near future, along with some ECM tuning. So one way or another, the issue will be fixed.

widebands arent a direct fit into a non wideband management system. it uses full volts, 1-5 on some for instance, instead of a range of .0 to .9v with .2 being regarded as decel/lean, .450 being stoic, and .82+ being rich/accel. i have pondered finding a way to step down the voltage but get the same response but judging by how i havent seen anyone do this or make a 'conversion kit' im guessing its not doable. megasquirt can handle them and will use a wideband as an 02 sensor, while ur at it you might as well drop the map and use a maf but this is many dollars. the 7730 +heated narrowband to me seems to be the best when factoring performance gains against dollars spent. the kits that companies sell use a wideband upstream of the narrowband and only desplay the data on a guage which you use for tuning at the track or on the road.

if you do know of a way of integrating a wideband into a narrow band setup id be interested. i also was curious what the 4 wire o2 sensor and the 5 wire were. mabye the detection element in the 4 wire is different and requires its own ground to accoutn for the 4th wire, or low heat and high heat circuts. either way im sure theres other options.

Francias or anyone else, if you duplicate what ive doen id like to get your feedback on using a heated o2. you may not have to do emissions but more gas mileage/performance is always good.

Most of the aftermarket wideband O₂ kits I've seen have a narrowband output, as well. While the sensor itself may not have narrowband output, the controller box included in the kit usually does. This allows you to use the wideband sensor to run your engine and log data simultaneously.

[This message has been edited by Blacktree (edited 04-01-2008).]

you didn't correct his spelling of CAMARO? after bUng? or WraPPing?

[This message has been edited by Nazareth (edited 04-01-2008).]

quote Originally posted by Francis T: Just had a thought, if it don't last you can get a vacuum switch/senor that will close below 15+" or lower of vacuum which would pretty much limit it to idle and off throttle.

Thats actually a really good idea !

Maybe you should supply one along with an O2 with your intake/exhaust parts?

didnt know the widebands gave a narrow output, id looked at a few in the summit and jegs catalogs and they didnt list it or i was just retarded and didnt see it or they didnt list it.
what companies have this kinda wideband?

as for the switch, it sitll wouldnt protect the 02 from the thermal shock on startup.

can you show us which wire is which? on the sensor, not the connector (lots of cars use the same sensor with blue, white and 2 black wires but their connectors are very different!)

i kinda figure grounding the 2 black ones is obvious, what about the white and blue, which one is supposed to be hot and which one is data?

For the O2 heater circuit, how long should it take before that circuit is set to %100 duty cycle?

merlot the o2 youre lookin at is a 4 wire, grab a 3 wire its much easier, plus i dont know what a 4 wire does differently. the heater circut is off of the two black wires, doesnt matter which is + or -. the blue wire is the signal wire. wire the 'on' switch for the relay to the A wire on the fuel pump relay connector. the rest is standard relay stuff. u wont need large wire since it only draws 1.5 amps

as for duty cycle i dunno on this particular sensor but they generally take 10-20 seconds to get to full temp but i dont think the ecu looks at it till the coolant temps hit 150

..

[This message has been edited by PaulJK (edited 04-07-2008).]

megafreakindeth
Check you PMs and let me know if didnt get through, was acting kind of strange?

(friggin forget it) ....

[This message has been edited by PaulJK (edited 04-07-2008).]

We like to keep everything as close to direct swap simple as we can; with that in mind I've been thinking what if 'I simply move our O2 bung from the big lower section up to the section just above the Y in the Y pipe? That would place it in the smaller pipe and also a little closer the exhaust ports and thus it should run hotter.

quote Originally posted by megafreakindeth: as for the switch, it sitll wouldnt protect the 02 from the thermal shock on startup.

I was thinking about this, and wondered if one could use a resistor to reduce the power to the heating element. The fun part would be figuring out the optimal resistance value, to balance between thermal shock and warm-up time.

quote Originally posted by Blacktree: I was thinking about this, and wondered if one could use a resistor to reduce the power to the heating element. The fun part would be figuring out the optimal resistance value, to balance between thermal shock and warm-up time.

Its a better idea to use PWM instead of a resistor, as that it how the controller in a car equipped with a heated O2 works. It doesnt modulate resistance, just how long a voltage is applied to the heater per second.

I was thinking of using a crystal oscillator, prescale and counter IC, variable resistor circuit, PWM circuit, and a flip-flop cut-on. Basically when you turn the key on it starts counting up which will change the resistance and then that will change the duty cycle until it hits a certain point where the cuty cycle needs to be %100 without the counter overflowing. That will be where the flip-flop will keep the regulator to the heater coils at %100 duty cycle, or whatever the maximum duty cycle is.

[This message has been edited by AP2k (edited 04-07-2008).]

I would be curious if you have the stumble when cold problem with this setup. I had a replacement bosch o2 that started working WAY too soon, as in about 15 seconds after starting the car. caused a rough idle and serious bog and stumble with light intermittent backfire. Winaldl logs showed it switching very soon after startup, and since this was early summer, the CTS was just hitting over 80 degrees. Someon posted the ecm setpoint for closed loop is somewhere around 48F which I have to think is not right, but may well be. The net overall effect was going closed loop too soon. This is not a high mileage motor, like 10k after a full rebuild. changedo ut the o2 sensor to an old gm one I had in my box, and car has been fine. I'll be curious to see if this gives you any problems in the warmer weather.

I'm using one of the later four wire O2 sensors that's normally mounted in the exhaust manifold near the outlet flange where the runners converge although it is only exposed to the heat stress of 3 cylinders I'm not sure the narrow band sensors are overly sensitive to location in exhaust as far as being to close considering some single wire O2 sensors and heated sensors were placed in stock turbo exhaust housings within inches of the turbine outlet. I believe the distance is mainly for a happy medium between a good exhaust mix between both banks and reasonable time to operating temperature. From my datalog the late model GM O2 sensor works fine, it was thought they were not compatible however, this was on an engine with a big cam and pretty rich idle resulting in a frequent open/closed loop switch. Once closed loop was reached according to my datalog it stayed there with a constant 12v source.

The Zeitronix datalogger I use for tuning has an output to the ECM that sends a converted wideband O2 signal to narrow band but I don't use it. Most of you know that WBO2 sensors are sensitive to high heat and probably wouldn't last long if to close to the exhaust outlet.

sorry, i was away all weekend losing in a drinking contest to a guy who had airborn, special forces, and ranger badges on his chest along with a rack of bars. i consider the contest a tie sicne my gf dropped long before either of us were really pushing it so i had to take her back home, lucky me since i had 5 dollars left.

paul jk i dunno what you posted but sorry for angering you

from what ive read and general common design is that the ecm starts watching the o2 at 150deg. i dont notice the transition anymore, before it would run fine till the car got warmed up and then the idle would suck. now it just warms up and works fine over the whole powerband, though i have no means of qantifying this i deffinatly feel a difference all around. i never felt any stumbeling or bogging with my heated o2 though it hasnt been very long.

as for thermal shock its not a super big deal, old volvos simply turn on and stay on. pulse modulation is a newer thing i think due to Eobd protocalls, i only work on euro cars so i dont know how gms been doing things. volvo didnt feel it nessesary to switch the heater on the front o2 when they added rear o2s to the mix, though they did have a 3 minute switch on the rear o2 because the cat apparently absorbs lots of heat(so do turbos, hence why stock turbos have o2 bungs in them, or precats right after the turbo, to increase lag and reduce emmissions ahem...audi) the use of precats, or cats on the exhaust manifolds may be why they modulate the sensors since the thermal variations are probably greater.

I was looking at possibly adding a heated O2 sensor to my car, just because the gas mileage is so poor. But from the research I did (which could be wrong), the Fiero uses a Titania (Titanium Dioxide, TiO2) oxygen sensor, which is of course a single wire, but works by using a voltage sent from the ECU, which goes to the sensor, whose resistance varies between 1,000 and 20,000 ohms depending upon the oxygen content of the exhaust gas (V = R*C), producing a signal between 0.1 and 0.9 volts. By wiring in a newer heated zirconia O2 sensor, wouldn't the supplied voltage from the ECM throw off the reading? Or what voltage exactly is sent to the sensor? The zirconia senor generates it's own charge, and sends that voltage signal to the ECM. Ideally it would be the stoichiometric 14.7:1 ratio @ 0.45 volts. Also, how would you wire the heater? Is the heater in newer cars constantly on, or does it turn off once the vehicle enters closed loop mode? From the original post, it sounds like the heater is on a long as the car is on?

I believe the difference between the 3-wire and 4wire O2 sensors is that the 3-wires use the exhaust manifold as the ground for the sensor circuit, like our 1-wire O2 sensors in the Fiero, while the 4-wires have a seperate ground for the heater and the sensor circuits.

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1984 Fiero SE

also some wideband systems dont use 2.5 volts as stoic, nor do most wideband to narrow converters call .45 volts stoic. some engine management systems dont even seek out a 14.7:1 ratio so those of you running other engines with other computers may have problems here, the fiero ecm is stupid simple and is the general market for 'universal fit' things

rwd pls, i think the zinconia sensor you speak of is the 4 wire, hence why it uses its own ground. i had figured they operated differently and needed their own circut sepearate from the exhaust, since new cars use them vs old ones i also thought mabye it was better/more responsive but im also poor/lazy so finding out will take time unlesss someone here simply tells me. i do not know what this bosch sensor is made out of but i can tell you that it does sweep normally and drives perfectly fine. ive looked at the datalogs and a 5gas emmissions analizer and its all good so i guess its not a problem. ill be the first to tell everyone if it starts sucking or blows my car up.

here is how to wire it up. its on all the time as long as the car is on, draws 1.5 amps

o2 sensor(pn listed above)
blue-02 signal wire
black- positive(or negative)
black- negative(or positive)

relay-any 4 pin relay, i used 14guage wire)
30 pin-battery +
86 pin- splice into the A wire on the fuel pump relay, this energizes the fuel pump relay and now also energizes my o2 sensor relay
85 pin- to ground, i also wired one of the black o2s wires in with this pin and routed the ground to the ecm harness ground located near the dr side decklid strut
87 pin- to the other black wire(this is now the + wire to the o2 heating element)

[This message has been edited by megafreakindeth (edited 04-07-2008).]

On the headers/Y pipe I'm now building for a customer I'm going to relocated the O2 bong to base of the junction (2 way collector) where header outlet for cylinders 2,4,6 connect to the Y pipe. That should get the temps up and it will also see/read the pulses from all cylinders from.

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Trueleo.com/fiero.htm
RSpiderII@aol.com

Even Beavis and Butthead know it's called a "Bunghole".
http://www.youtube.com/watc...wI7A&feature=related

quote Any muffler shop should be able to weld threaded sensor adapters called 'bungs' into a hole in a header or collector or reducer.

From this article.

http://www.regnirps.com/AutoSense/autosense.htm

[This message has been edited by avengador1 (edited 05-09-2008).]

yeah yeah, but bung just dont have a ring to it like bong

quote Originally posted by avengador1: Even Beavis and Butthead know it's called a "Bunghole". http://www.youtube.com/watc...wI7A&feature=related From this article. http://www.regnirps.com/AutoSense/autosense.htm

After reading this thread a while back, I thought this might be a good idea to try on my base '86. After the engine was warmed up on a hot day and left to sit for a few minutes, the car would not start. Unplug the oxygen sensor, and it would start and run no problem. Today, I installed a bosch universal 4 wire and it makes a huge difference. hot starts are no longer a problem, and the car runs better overall. Like MFD said, if something goes wrong I'll post up, but otherwise I really like the mod.

Technical info:

Black (signal wire) to factory harness
one heater wire (white) connected to switched side of fuel pump relay
other heater wire (white) and ground wire (gray) grounded to transmission (convenient to put all the wires close together.)

Update on the heated O2 sensor on my car.

Burned it out after 15k miles. Possibly due to oil burn-off from leaking valve guides/ seals, or lack of a pulse circuit to slowly warm up the sensor. I'm going to revert back to an unheated sensor and see how it does for apples to apples comparison of two new sensors on a stock engine.

So would it be a bad idea to just put power to the heater? Should it be pulsed on and off instead? I am not worried about it burning up after 15,000 miles, they aren't that hard to change or that expensive.

We've expereinced a number of problems with many brands of O2 sensors. The only ones that have ever worked right have been the AC Delco and the Denso brands.
The Bosch brand seems to work OK too but they don't last. All other brands that we've tried give an unstable idle, either run too rich or too lean and just don't cut it.
You're probelm may be just that you are not using a functioning sensor as the heater in heated O2 sensors is normally just turned on for a few minutes until the engine gets warm, then it is de-energized.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite.
87GT - 3.4L Turbocharged engine, modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

Which cars did the Delco O2 sensor come in so I can just go into a parts store and get one? It will just screw in to the bung on the y pipe right? I have the trueleo header/intake set up too so this may help the idle a bit. Once I get it I will post the difference.

quote Originally posted by Riddick85: Which cars did the Delco O2 sensor come in so I can just go into a parts store and get one? It will just screw in to the bung on the y pipe right? I have the trueleo header/intake set up too so this may help the idle a bit. Once I get it I will post the difference.

AC Delco part # AFS-22 or AFS-21.

That's what I have / bought.

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fierogt28

88 GT, loaded, 5-speed

I have been trying and trying to find a car with a sensor that would work for this but I cant. As far as I can tell from my research AFS-22 or AFS-21 are both singe wire unheated O2 sensors that will fit the Fiero and various other vehicles up to around 93. I have found a few heated ones I think will work but I am not sure, part #'s AFS75 and AFS97. Can someone tell me if I am correct or give me another viable alternative that isn't $70and up. Thank you!

Quick look at the ACDelco site shows the AFS21 was used on 2,633 models starting in 1982 and ending in 1999.

The AFS22 was used on 3,455 models starting with the 79 Cadillac and ending with the 97 Chevy/GMC 7.4L V8.

The Fiero models are on both lists.

seeing this post again thought I'd add, I have since installed heated o2 sensors on both my turbo 86 and my NA 87, both have headers. very happy with the results. I think I used AAP sensor 3000?

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Trueleo.com/fiero.htm
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