Another bloody sensor issue...

[Fatty]

whether or not it makes sense to you really is beside the point. a few other people have posted that t doesn't make sense to them either, so rule it out as the cause. with all due respect to these people, they shouldn't be ruling it out as in my experience, there is a correlation. i don't know how, or why, but there is. so just think, a few other people (myself included) who have had the EXACT SAME PROBLEM as you are having, have FIXED THE PROBLEM by REPLACING THE O2 SENSOR.

i know what i would be doing if i were in your shoes.

[lowmiata]

How I understood it was:

The car runs in start up mod for certain time then when it says ok lets look at the o2 reading to change over to fully run it was getting a mixed signal because the 02 sensor was buggered

Easiest way without spending any money to find the problem:-

wait till next day unplug the 02 sensor
(plug is behind coil pack)
if you unplug the 02 sensor the car wont change modes as it cant get a signal back from the 02 sensor and runs in rich mode.

This was how i diagnosed the problem
FWIW mazda couldn't even find the problem they knew it had something to do with it but couldn't explain it as there were no fault codes

I actually drove for a couple of weeks with no o2 sensor as at the time mazda quoted 420 bucks for a new one ( i went to my local exhaust shop and they put me onto the repco one)

so its a no cost test to rule it out
worth a try in anyones language

let us know how you go
02 sensors do fail if the car has run rich for some time this can kill the o2 sensor quickly(don't know how I was told this) so don't quote me on that!

so if you unplug it and the car doesn't stuter and stall after 3 minutes you know what you got to buy!

Ryno.

[Nickers]

Thanks Ryno for taking the time to explain it all.

A pain I know, but you've covered it in brilliant detail! I'll be unplugging tonight and will report back tomorrow with my progress. Appreciate the help!!

Nothing worse than an Orgasmo that stops itself...

[lowmiata]

Thanks Ryno for taking the time to explain it all.

A pain I know, but you've covered it in brilliant detail! I'll be unplugging tonight and will report back tomorrow with my progress. Appreciate the help!!

Nothing worse than an Orgasmo that stops itself...

It was only after reading the last few posts about explaining why it had anything to do with the 02 sensor that i remembered how i solved the problem.

If that doesn't solve the problem maybe try swaping the ecu and see if a known working one works in its place

I would lay money on it that it will solve the problem though!
If your car has 200 or more thousand k's on it then its quite possible its the original o2 sensor!
and as a few have stated they have had to replace theirs!

Good luck anyway!

[Garry]

My first O2 sensor only lasted about 60k km. It didn't show any fault codes on the diagnostic equipment but the guys at Chiptorque checked it out and found it was operating very slowly. Apparently they start doing this a while before they die. The biggest change I noticed after it was replaced was how much smoother the car ran while it was in it's warm up phase.

[lowmiata]

I'll be unplugging tonight

Any news?

[Nickers]

I decided to do things one by one to make sure I know what the cure is when I cure it, and the engine bay was a little warm after a spirited drive home so instead of disconnecting the O2 sensor I reset the ECU last night.

This morning the car seemed a lot smoother when cold, in that it didn't drop revs so quickly. For the first 2-3 minutes of running it still lacked power and any willingness to rev much past 2,500 rpm though, so I'm leaving one more night to properly test. I had to let it warm a little before driving to defrost the ice on the windscreen, so the test may be skewed.

And we're busy packing to move into our first home (owned by the bank) so the missus is 'encouraging' me to get stuff organised, so spare time is minimal.

I've got tomorrow arvo off though, so if it plays up in the morning I'll disconnect the O2 sensor and see how we travel.

[Fatty]

sounds good mate. are you clear on where to disconnect the o2 sensor? if you need a picture or anything let me know.

[Sean]

I might have a spare stock o2 sensor laying around (for a 1.6).

If that turns out to be the problem let me know and I'll go check the shed - if I can find one it's your for whatever postage costs, I can't garauntee I have one at this stage though, I'll check over the weekend.

[Nickers]

Well, this morning the thing is holding revs when cold and blipping the throttle, but it still seems to be running rich for the first few minutes... gets bogged down and struggles to accelerate with any enthusiasm.

This is my first winter with the car, so maybe I'm just expecting too much. Overnight temps here are hitting 0 degrees, and the car is parked in the street overnight. The morning sun doesn't hit it, as it's sheltered by the house so it gets pretty cold. At the new house, the car will be warmed by the morning sun (still outside until I build a garage) but it'll be interesting to see how this changes things.

Thanks Fatty, I had a squizz and found it lead back near the base of the coilpack. Am I on the right track? I might give this a go anyway and just see if things change.

Thanks for the offer Sean, I'll let you know. I'm loving this forum, has saved me weeks of troubleshooting and replacing bits! Tip of the hat to you all!

[JBT]

This is my first winter with the car, so maybe I'm just expecting too much.

I don't think so, it should run fine even at -10 degrees. There is something wrong with it from the descriptions you give.

[Fatty]

Thanks Fatty, I had a squizz and found it lead back near the base of the coilpack. Am I on the right track? I might give this a go anyway and just see if things change.

yep, that's it mate. just unclip it there.

[Boags]

a few other people (myself included) who have had the EXACT SAME PROBLEM as you are having, have FIXED THE PROBLEM by REPLACING THE O2 SENSOR.

I'm interested to see if unplugging it makes a difference. If it's an NA6 then the O2 sensor is well overdue for replacement anyway, but I won't be surprised if it doesn't fix it. I also won't be surprised if it does; the explaination Ryan gave was very clear and makes sense...

It just doesn't sound like the same problem to me... It might just be a difference in descriptions, but the problem Nickers is describing does not sound like what fatty and lowmiata and many other forumites suffered.

It just seems a little fishy to me. Keep us posted Nickers.

Boags

[marky210]

Hey guys

Ive been following this topic as i to have been having similar problems as described by \"Nickers\" in the start of this topic.

I had my suspicions that it was the oxygen sensor and i followed the test procedure that \"lowmiata\" said to try.

I have a NB8A and i unpluged the oxygen sensor which the plug is at the front of the rocker cover- This was done when the car was cold as ice first thing in the morning. After i unpluged the oxygen sensor i then started the car and as soon as it started up fine and was idleing it made a few little stutters and then was fine(i asume the computer could not read or connect with the oxygen sensor and it switched to map mode at this stage) and idled perfectly for a good 10min untill the car was reading warm on the temp gauge. I gave the car a few reves and all was fine The car never run or idled roughly after 3min and still did'nt after 10min

So from what Lowmiata has descibed it would seem like my oxygen sensor is buggered and needs replacing

What do you guys think

Any help would be greatly appreciated

Cheers, Mark

[lowmiata]

Marky the sensor you unpluged was at the back of the cam cover yeah?

you said front in your post