Still on my O2 sensor...

Leon (and others... :-) ) can you give me an opinion? Today i have measured the tension of the O2 sensor. With warm engine, at idle, are indicated 0 volt. With engine to 3000 rpm, the sensor marks 0,50/0,60 volts, sometimes

0,30/0,40. When the engine comes down at idle the value is 0 for a moment, then go up to approximately 0,40/0,50 for another moment, and finally comes down to 0. Accelerating repeatedly, the value of the O2 sensor go up approximately to 0,50/0,60 volt, but it never doesn't go up to 1,00 volt... Moreover, there is a little lag when i press the accelerator at idle... What do you say?... I replace? Unfortunately I don't find in aftermarket the NTK O2 sensor for my '91... Have any idea to buy an OEM O2 sensor, without spendig 300 euros?! (Is the cost here, in Italy...) Thanks, Stefano
Reply to
Hammer®
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I ask you patience... : -) On the web site

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i have seen 3 different O2 sensor for my '91 Miata The first one is "Bosch", for 21,99$, with comment: "universal". The second is "Echlin", for 25,49$. The third is "Beck Arnley", to 43,99$, with comment: "Replacement Type". My questions are:

1) Which difference between this parts? 2) Is the "Beck Arnley" an OEM part? 3) I have found on
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a Bosch oxygen sensor for 39,95$ (Product ID 712-126); is this the same O2 sensor found at napaonline.com? 4) Someone can suggest me what's the best one? Many thanks :-)

-- Hammer® (30,115,Italy) Mazda Miata

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Reply to
Hammer®

The "beck arnley" is probably manufactured by echlin since echlin bought the echlin company. Beck Arnley is owned by Dana corporation. Your OEM (original equipment manufacturer) O2 sensor was probably NGK since that is what my Mazda had in it. I replaced mine with another NGK but have also used Bosch in other vehicles. As a rule they all have to meet a specified performance criteria and all have a maximum life expectancy of about 80,000 Km's. Some brands seem to stand up better and last longer but I think that is also dependant on the overall health of your engine. Since they all have to meet the same performance criteria to be marketed for that application the choice of how much you want to spend and which brand you want to go with is your decision alone. One final note "universal type" O2 sensors quite often require cutting the wire leads off of the old sensor and splicing them on to the new one since it does not come with the leads. This is done to cut down on inventory since the wire connectors and leads can have dozens of variations using the same sensor. The NGK sensor I put on my Mazda came equipped with the correct lead and plug for my application. One is not better than the other, the way it is is the way it is. Regards, Lugnut

-- "They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety"

Reply to
torque wrench

All I can give you is what the Enthusiast Manual for the 1.6 l says. It should show about 0,55 when steady at 3000rpm. 0,5 to 1 when engine speed rises, 0-0,4 when engine speed falls.

Mazda dealers can conduct more thorough tests, but I doubt that would be much cheaper than putting in a new sensor at the prices you quote.

If Napaonline returns them for the early Miata, they should fit and work.

Leon

Reply to
Leon van Dommelen

Gee, I hope they did not pay any really big money! :)

Sounds like you should go for the cheapest. $20 sensor and a fairly easy instal: they don't come much better than that.

Leon

Reply to
Leon van Dommelen

Sounds like your oxygen sensor is working fine. It's producing signals like it should. If the signals don't match what you expect, look to what would cause the wrong mixture rather than shooting the messenger.

At idle the system is running open loop and apparently runs lean.

Under most operating conditions it should read somewhere around 0.5V, indicating closed loop operation is correctly maintaining the mixture to about stoichiometric.

Under full throttle it should run rich, reading around 1V.

And of course there is a time lag for all these readings.

Reply to
Graham

Many thanks to all, i'm going to buy a new oxygen sensor, probably Bosch. I haven't yet understood if there are two different "universal" Bosch O2 sensor (22$ the first one and 40$ the secon one) or these are identical, except the dealer cost... Anyway...thank you, guys :-)

-- Hammer® (30,115,Italy) Mazda Miata

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Reply to
Hammer®

You've measured the output from your current one and demonstrated it is working.

If the output isn't what you're expecting, look for the reason that the mixture is wrong.

Reply to
Graham

I have checked all that i could check, except o2 sensor... I'll tell you the results... :-) Anyway...Thanks!

-- Hammer® (30,115,Italy) Mazda Miata

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Reply to
Hammer®

As I noted, the EWM says that dealer has special tools to conduct more extensive tests. The existence of those tests indicates that simply measuring rough voltages may not tell the complete story.

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I quote:

"The effect of sensor degradation can range from a subtle shift in air fuel ratio to a completely inoperative closed loop system. With respect to driveability and emissions diagnosis, a silicon contaminated sensor will cause the most trouble.

When silicon burns in the combustion chamber, it causes a silicon dioxide glaze to form on the oxygen sensor. This glaze causes the sensor to become sluggish when switching from rich to lean, and in some cases, increases the sensors minimum voltage on the lean switch. This causes the fuel system to spend excessive time delivering a lean mixture.

It is often difficult to identify a sensor which is marginally degraded, and in many cases, vehicle driveability may not be effected significantly."

I don't know about Hammer, but my sensor is 110kmi old, and my wideband O2 indicates a slightly rich mixture when the engine is heated up. I'll replace mine today. It will at the minimum mean one less thing to worry about.

Leon

Reply to
Leon van Dommelen

OK, thanks for the reference. I had never seen any oxygen sensor failure except complete loss of rich signal.

Reply to
Graham

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