Bargain Basement Motoring

[Paul-R]

Fortunately exhausts seem to last much longer than they did 30 - 40 years ago.

The last vehicle I had to replace an exhaust (or even part of an exhaust) was my 1989 Austin Montego estate. The 2001 Xsara and 2003 C5 that succeeded the Montego went on to their next owners with original exhausts still present. I think I had to have a minor spot of welding on a bracket on the Xsara but that was all. The current 2013 C5 X7 and 2015 308 have required no attention at all.

[NewcastleFalcon]

The first part of the job is now off the car and on the grass.

The upstream O2 sensor looks decently removable, the downstream one less so.

the Upstream plug at the end of the wiring looks to have been mangled somewhat on one of the pins. More likely on assembly than on removal. May well have caused some gremlins.

Neil

[NewcastleFalcon]

The sensors are out, new ones or reuse that is the question?

Neil

[mickthemaverick]

Now they are out they won't be too hard to get out again if they don't work properly, so I'd carefully clean them with brake cleaner and then insert with a dab of copper grease and try them. If they work you'll save splashing out!!

[NewcastleFalcon]

Thanks Mick, Yes it was quite a surprise when a reasonably sharp blow with a hammer on the end of a 22mm spanner loosened those sensors so any necessary replacements could be done quite easily.
Not sure if a simple resistance test can prove whether an O2 Sensor is good or bad..

On looking at the evidence of my dismantling I could probably have got away with a more bargain basement result ie one clamp renewed between the cat and centre pipe..

Major goal is to get it through that fast idle emissions test at the next attempt, The last test was done with an obvious leak of exhaust gases at the cat/centre pipe join, simply fixing that , may well get the emissions pass needed on its own.

A couple of new O2 sensors might further assist, and that damaged pin on the old upstream one may even be contributory factor to that emissions test initial fail.

Neil

[CitroJim]

Great work so far Neil

Not sure if a simple resistance test can prove whether an O2 Sensor is good or bad..

No, not really, it can only confirm the heating element is not open-circuit.

Do you have a diagnostic system for this car that will show live data from the sensors? That's the only way to know if they are truly good.

[NewcastleFalcon]

Do you have a diagnostic system for this car that will show live data from the sensors?

Not in the bargain basement toolkit Jim


The only intervention is fit new sensors should live data come up with anomalies in the sensor function and I am leaning towards just doing that, plenty on the net local factors under £30, NGK and Bosch a little more. I think the best opportunity for an emissions pass for this MOT in the shortest time, will be fitting new sensors along with the new cat, eliminating the doubt of whether the old sensors are good or bad.

Neil

[CitroJim]

Yep, fully understood Neil!

One way to (kind of) determine if the sensors might be OK is if the Lambda readings on the emissions result sheet is within limits...

[NewcastleFalcon]

Thanks Jim. These were the emissions test results...

One way to (kind of) determine if the sensors might be OK is if the Lambda readings on the emissions result sheet is within limits...

The Lambda min limit/max limit are 0.970/1.030

Fast idle Test results
RPM 2795 (Pass) CO 0.387 (fail max 0.300) HC 17ppm (pass) Lambda 1.028 (pass)

Second Fast Idle Test
RPM 2823 (pass) CO 0.005 (pass) HC 9 ppm (pass) Lambda 1.037 (fail)

Bit of a marginal failure but test was done with a leak of exhaust gases between the cat and the center pipe (after downstream O2 sensor.)

Neil

[CitroJim]

That was quite a marginal fail Neil... I'd say from that the sensors may be a bit tired but the leak will not help. Cat looks as if it might be good...

I've seen tired sensors where they get very slow to react.

[NewcastleFalcon]

The random hand has played its part

When cleaning the downstream sensor it made a break for freedom and escaped the embrace of the cleaning cloth, and landed softly on concrete and came off second best...

Nice when your options are ruled down to one

New sensors it is...

Neil

[CitroJim]

Definitely duff now then!

[CitroJim]

Oh, and don't use cheap eBay ones. They last no time at all in my experience...

[NewcastleFalcon]

Ever wondered what a lambda sensor looks like without some of its clothes?

Not exactly a Big Clive detailed dismantling but the result of a 3 ft. drop onto concrete. Fragile as an egg. The white stuff looks like ceramic of some description.

perched on top the new sensors box

Oh, and don't use cheap eBay ones. They last no time at all in my experience...

Not me Jim, I've gone for quality with those CAMBIARE sensors, right wiring plug, £43 each from the local car parts shop. (Yes I've never heard of them either but right now they'll more than do particularly if in their newness they get the emissions back in the pass zone )

Neil

[CitroJim]

Ever wondered what a lambda sensor looks like without some of its clothes?

Not exactly a Big Clive detailed dismantling but the result of a 3 ft. drop onto concrete. Fragile as an egg. The white stuff looks like ceramic of some description.

Zirconium I believe Neil....

The sensor is, in effect, a small weak battery that uses oxygen as an 'electrolyte'. The downside is that it needs to be very hot (>800 degrees I believe) and hence the need for a heater around it.

Pleased you have good quality ones