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I am hoping someone will help me with 2 problems

(1) Can anyone tell me what the symptoms are when the O2 sensor is to give trouble?
(2) Anyone familiar with the plastic clips that hold the fuel lines to the fuel filter on a 1999 NB8A?
I went to change the filter expecting to find the normal metal retaining clamps that you use a pair of pliers to remove. Instead I found plastic snap on type clips that I didn't want to stuff around with.
Can anyone HELP?

Fuel consumption, mostly during light driving and highway running, suffers as the O2 sensor ages. Basically it reads leaner than it really is so the ECU compensates by making the mixture richer than it should be. Sooty exhaust pipe is a useful indicator. If it's really bad then the engine could be obviously rich, like you're running with the choke on in an old carburetted car.

Similar problems can arise from a faulty engine coolant sensor, a thermostat stuck open or a thermostat with too low a heat setting. The ECU richens the mixture because it is told that the engine is still cold.

What that manga guy said Your car will still run relatively fine, and you might feel sluggishness at low revs in higher gears, or when taking off from stand-still, because of inefficient AFR.

WOT acceleration should remain the same as it becomes open-loop and the EMS ignores the Lambda sensor.

Can't help with (2) sorry. Were you just afraid of braking them?

Thanks for the info on the O2 sensor.
Just one thing it runs rough when cold and coughs and splutters in 1st until you give it heaps of revs. It comes good after it has warmed up, but until then it feels like it is running a little rich. You can also feel it in all gears. It almost feels like a flat spot. Can it still be the O2 sensor?

Hi all,
Just to let you know I have solved my problems. It turned out to be a combination of a completely stuffed fuel filter along with a O2 sensor that was acting up. It turned out after checking my records Mazda had not changed the fuel filter at any service. I have been told it is a good idea to change the filter every 20,000km's as there is a bit of crap fuel around. It sounds like good insurance to me so as not to get engine trouble. She is running as she should. I am waiting on a new set spark plug leads.

12 years old and never had a fuel filter change? wow! i do mine every 40,000km.