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Discussion Starter · #1 ·
Hey guys, I just probed my 02 sensor on my 91 GT (it has ODB1 and I was probing the o2 sensor on the exhaust manifold).

Anyway, I got NO READING from it, and ever since I bought the car, the "check engine" light has been on. I was told by the owner that she was told it was a problem with the o2 sensor in the engine... well the exhaust manufold o2 sensor is the only real o2 sensor I know of... any I probed it and sure enough it´s dead, at least it looks dead from the (lack of) voltage reading Im getting from it.

I just wanted to verify that this was the problem, because I´ve been having this one kinda weird idle problem:

- when I let it idle, then give it just a tiny bit of gas (just to push it off balance a little), the rpm won´t drop back to normal rpms, but it will drop BELOW normal rpms, then back up to normal. It takes about 2-3 seconds for this whole process to happen, and sometimes it drops really low, to the point of almost stalling the engine. Would the 02 sensor have anything to do with this? (I was personally thinking that the ISC valve was the problem, but this o2 sensor may be causing this problem too I guess...)

anyway thanks for any input :-]
 

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oh yeah sirg, how did you do your headlights? Ive been wanting to do something like that for a long time.. can you explain?
 

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Discussion Starter · #4 ·
how can you pass emissions without the o2 sensor? hows your gas mileage? any knocking? how´s the idle?
I´d just imagine it´s tough for your car to know much about the fuel/air mix if it doesn´t have an 02 sensor... I´m planning on digging one out of a junk car at the yard, but I honestly am not totally sure if my o2 sensor is dead or I´m just retarded.

concerning my angeleyes conversion, it´s quite simple, actually. I only used 3 tools for the conversion:
1. clone stamp
2. burn
3. transform
:-]

Actually, to put angeleyes on an escort, not only would you need to first shell out 350 or so bucks for the headlights themselves, but then you´d have to fabricate a mounting bracket and possibly modify the existing bumper and grille to accomidate these new headlights, and then on top of that do the wiring to them also.

I personally am going for a much cheaper alternative, which still has that cool angeleyes effect. allow me to explain:
first, I´ll start off with some E36 headlights, and then run to the machine shop and fabricate some new mounting brackets for em. you can get the headlights for about 80 bucks on ebay.

then, I´d take the casing apart, and run several coils of glowwire around the light socket. here´s what I´d use for the wire:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3006600150&category=20334

Connects to the 12V DC power supply and comes with its own sine transformer. I´d probably get a higher quality one of course, but the same idea. Then, after all is said and done, I´d get that same killer angeleye effect, all for around 100 bucks and an afternoon of fabrication and improvisation.
 

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well my engine dosnt knock or ping, but it did cut my gas milage down, Ive been running the car like this for 2yrs now and it hasnt done anything to it, its actually picked up some power. trust me when ya can dust a stock gt with it, ya can tell... and my idle is nice and level. my idle used to bounce like a crazy person so I replaced my plugs and it quit
 

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Disconnect the O2 sensor and see if anything changes. I´m assuming you´re reading the voltage at a really low level... I forget what the range is for an oxygen sensor, but I know it´s really low (400mV at idle I think). Whenever you disconnect it or the car isn´t getting a signal from it, the computer will assume a rich setting to be safe. If you disconnect it and it runs exactly the same, you may as well replace it... but I´m not sure if that´s your problem.
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when I let it idle, then give it just a tiny bit of gas (just to push it off balance a little), the rpm won´t drop back to normal rpms, but it will drop BELOW normal rpms, then back up to normal.
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[/TD][/TR][/TABLE] I´d check for vacuum leaks and check out the TPS... sounds like the problem I was having before I replaced mine.

But, I am relatively new to these cars and the EFI, so someone please correct me if I´m wrong :-]
 

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Discussion Starter · #7 ·
beav- thanks for letting me know about how he ECU thinks that "richer is safer". That´s good to know so at least if my O2 sensor is fuxored up, then I´m at least wasting money and not killing my car.

I cant hear any vacuum leaks... I´ll check the TPS with a voltmeter.
What hoses should I check for vac leaks? I replaced the intake hose. I was thinking that the hose that leads off the resonator box on the intake hose might have somethng to do with it.... hem.

and I know that the o2 sensor is from 0-1V (0.000 - 1000.000mV) and I read it on the sensitive scale, and I saw ZERO needle movement.

Also, the car runs exactly the same with it connected or disconnected.
 

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Discussion Starter · #9 ·
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11-02-2003 at 17:12, Pimp_scort_89_GT wrote:
DO NOT PROBE AN O2 SENSOR WITH AN ANALOG METER!!!!! You will fry the o2 sensor. Ask Siragan. ;-)
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:-]

ps it was fried before I got to it... now it´s really fried! w0oT!!1 :-] :-]
 

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Discussion Starter · #10 ·
so... what kind of o2 sensor do you guys recommend I get to replace it? where can I get it?

and exactly what is the "right" way to test the voltage on an o2 sensor? I hear it´s to place the red end of your DIGITAL HIGH IMPEDENCE multimeter to the o2 wire itself, and then to attach the negative end to the casing of the o2 sensor. is this right?
 

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This thread is particularly interesting to me. For a while now, I´ve noticed a loss of power, and a smell of gasoline when the car´s cranked and idling, as if running too rich. Performance mods include conical intake, armor-coated Pacesetter 4-2-1 header and Pacesetter catback exhaust. Power was great after the pieces went on, but I´d noticed a gradual decline and the smell. Well today I simply disconnected the O2 sensor figuring that if nothing changed, then the sensor would be bad. What I found was just the opposite - it was as if all my lost power returned. My question - could that be caused because the computer is overfueling, creating a run-rich condition? I would think that would sap power. OR, could the O2 sensor be degraded to the point where it´s not generating an error code but is affecting performance? The difference today was quite noticeable, so much so that I´d consider running with it disconnected, but I just don´t think it´d be good for the car, nor for economy (especially with gas prices being what they are).
 

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You´re right about the method for testing the sensor. A good sensor will switch back and forth, between 0 and 1 volt, about 10 times a minute for a cold sensor. A hot sensor will switch more quickly.

I´d recommend a book by Charles O. Probst, published by Robert Bentley, Publishers. It´s titled "How to Understand, Service and Modify Ford Fuel Injection & Electronic Engine Control"

There are two books with the same title. One is for 1980-1987 cars, the other for 1988-1993 cars. Read this, and you´ll know more than you ever had a desire too.... :-?
 

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14-02-2003 at 15:05, Zeemax wrote:
Performance mods include conical intake, armor-coated Pacesetter 4-2-1 header and Pacesetter catback exhaust. Power was great after the pieces went on, but I´d noticed a gradual decline and the smell. Well today I simply disconnected the O2 sensor figuring that if nothing changed, then the sensor would be bad. What I found was just the opposite - it was as if all my lost power returned.
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Hey, could the exhaust mods have anything to do with the functioning of the O2 sensor? I mean, I thought that the sensor was located at the exhaust manifold, so how was it hooked up when you went to a header? I would think that if an O2 sensor were moved to somewhere other than where it was meant to be, even if the sensor itself were ok, it would have an effect. Just an idea, can anyone shed some light?
:p
And yeah, I bet that running too rich would result in a loss of power, and a gas smell too. Have you checked your plugs to see if they´re fouled up?
 

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Discussion Starter · #15 ·
My 91 GT has a "gassy" smell from the exhaust, also. I think it may be running rich or something, I dunno, but I want the o2 sensor replaced and working. What kind of o2 sensor will fit? It´s a single wire o2 sensor.
 

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The location of the O2 sensor on the stock manifold and the header is about the same spot. So I don´t expect any significant differences in the amount of exhaust gas hitting the sensor. I just noticed that after the parts, power improved noticeably. Couple of months later, power drops, fuel economy drops, and the gas smell appears. Disconnecting O2 sensor restores power. Oh, and plugs are fine, wires in decent shape. We´re under ice right now so as soon as it thaws out I´ll be replacing the O2 sensor. Siragan, you asked what type would fit. I believe you can get a generic one from a local auto supply store. Advance Auto has one for $35.00 - seems to be the cheapest yet. Stock from Ford (provided you can get one) is $85.
 

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Discussion Starter · #17 ·
I was thinking of this one:
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=2403609184&category=33609

What do you mean by "I just noticed that after the parts, power improved noticeably"? What parts? When you took the parts off or put them on?

I´ve tried the o2 sensor connected and disconnected. Both scenearios it seems to drive the same, both senarios it has the "check engine" light on in my idiot lights cluster.

However... I am installing my RX-7/K&N FIPK intake! looks super woot.
 

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15-02-2003 at 23:10, siragan wrote:
However... I am installing my RX-7/K&N FIPK intake! looks super woot.
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i haven´t heard anyone use super w00t before...
get pics up of that intake when yer done!!
 

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Haha. A guy in high school had an old derelict El Camino and he did that spark plug in the exhaust trick. Rigged it up to a piezo ignition like found in gas grills. It´d only shoot a little over 2 feet, but looked the business.
 
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