What are the symptoms of a dying exhaust O2 sensor?

My EL has been a bit of a whinger for a while.. and its getting worse.

Its never been the same ever since the distributor was replaced by someone who I don't think knew enough about EL's to really get it right, and although its been looked at since and apparently there is nothing wrong with it, and a bunch of things done, its still not running right..

what has been done?

Distributor
Leads
Plugs
Head Gasket
Injectors
Ignition coil
ALternator

symptoms..

Starts ok.
after running for about 20 seconds, the idle drops and it sounds like its running on 5 cyl, then pops back up. Leave it for a little longer and it might nearly stall before the computer suddenly realises "oh my idle is low!" and pops back up again.

Moving away gently, (after getting out of the driveway) trying to accelerate (gently!) and the engine shudders, hesitate, and doesn't want to run like its running out of fuel. Put the boot in, and it comes good (as good as cold gets) and over about 2000 RPM, it seems to run ok, (although not as good as it should be) Obviously though running while its cold like this is not advisable.

Once the engine is warm (and it takes a long while to get warm... 20 minutes or more sometimes) it shows the same symptoms, but not as pronounced. move away from a stop, and it hesitates, and doesn't give you full power, shudders slightly... sometimes pops and splutters mildly. Put the boot in, and it goes like a new one (keep revs high, and it runs well.) At lide at the lights about 50% of the time it pops, and mildly splutters (not a particularly smooth idle.) which is annoying to say the least.


I realise its a 195000Km engine, and transmission, but its been looked after, (I'm not a lead foot, or even an steel foot.... alumimium is about as heavy as it gets) serviced properly, by the right people, and was fine up until about a 2 years ago... Its it just "old car syndrome?"

I've got time of in March, and I'm thinking of taking it back to Crescent, and have it gone right over, top to tail... its due for service then anyway.

anyways sorry for the long winded whinge! Its just frustrating to the point I've been look at ditching the mongrel and getting a new one, but can't afford it. I had originally planned keeping this one for a long time.

Last edited by 96ghia on Wed Mar 12, 2008 12:05 pm, edited 1 time in total.

Sounds like you may have a intake (air) leak,
I had to replace the injector O rings (got a service kit).
Another time it was the fact that the intake bolts (some) were loose, I replaced the intake gasket at that time.

blocked cat by any chance?

When they replaced the distributor, did the set the timing right? It could be out of alignment giving you misfire and causing the popping.

Might check the timing out again with a timing light...

phong =P~

I suspected they didn't, but I'd had the base timing re-checked twice, by 2 different workshops, who both said it was good.
Also, it comes good after about 2-2500 RPM. Its only when the engine is at idle, or going gently that its not right.



I have had an inlet manifold gasket leak before, (when I first got the car) and it was displaying symptoms like this then as well.. thanks for the reminder.

I had the Head Gasket done about 12 months ago now, and this should have all be replaced when that was done I think. I'll get this checked at the next service. The injectors were cleaned off car at about the same time (while the head was off) so I'd guess that any dud O-rings should have been noticed then.

mines beeen doing this for ages too, seems no-one on here has a solution....and ive looked for a long time..

ive found that it doesnt do it when on LPG only petrol.....so that seems to indicate fuel system...ive replaced fuel filter and fuel pump but no improvement....

also i find that if ive run on lpg for a long time and then use petrol it seems to be better

im thinking it might be injectors

I'm having the same symptoms as you, Ill be watching this with intrest. If i manage to fix mine, ill let you know

As 'SgtBourne' advises, check the cat and while your at it the rest of the exhaust for flow.
Of all the many things you list that you've had checked the exhaust doesn't get a mention. At 195k you've well and truly gone past the date for checking the cat. That and the pcv valve are the most neglected parts on a car that can cause so many problems, just like yours.
An exhaust is easily tested yet nearly always ignored.
Cheers,
Paul

how can u test the exhaust without taking it apart...

gogetta, don't know about your car, as a cat problem would be there all the time.
"how can u test the exhaust without taking it apart..."
This is one way, it's not foolproof because it's experience that counts here.
No responsibility taken, act with due care.
Same principle as testing spark plugs/leads, ie if the plug/ lead is good the revs drop, if bad they don't.
Have the car idling a little bit faster than normal and progressively block the tail pipe [eg. with a wet rag].
Judge how quickly the engine begins to struggle and the revs drop. How quick that happens, or if the engine stalls, tells you the condition of the exhaust.
A clear system will continue to run but struggle, a clogged system will nearly die, a really bad one will often stall.
As you've never done it before, try it on a car that has no known problems, [DON'T do it for too long as you may damage a good system] before trying it on the suspect car.
I'm told that after a long run at night, blocked cats can have a red glow on hot spots, I have never seen this but I have known stuffed cats to rattle when shaken.
Any car that has been using the really cheap blended fuels either has or soon will have cat problems, strictly my opinion based on what I've seen and done.
BTW, when anyone gets their cat replaced take the dead one to a recyclers and get at least $50 for it, or ask for a discount because of its scrap value.
Cheers,
Paul

Cheers. I'll get this looked at as well. You're right, exhaust isn't something I've looked at before, as its one of those things that just seems to "work" and I've never heard mention of it, (or assumied that those doing the checking would let me know if there was a problem.

I was hoping to replace the exhaust some time early this year, as its a bit bashed around, but impending fatherhood re-aligned my spending commitments

And I would definately get the cat recycled. The Platinum Palladium and Rhodium is worth big money.

"but impending fatherhood re-aligned my spending commitments"
I know what you mean! My spenging is always being re-aligned. I have 9 children, seven girls and two boys, 41yo to 1.5yo.
Cheaper to run a drag rail and go sailing... combined.
Cheers,
Paul

i had the same problems so i thought it was a cat so i took my o2 sesnor out and took it aroung the block and it came good so i put a new cat on it and it was fine ever since but when i put a new 2.5 inch system i pulled the mufflers aparts and there where bits of my old cat

sorry but what did the O2 have to do with it??

Probably relieved the pressure from the blocked system through the sensor hole as it's before the cat.
Paul