MX5Ireland

OK - I've been here before.... as some others have too...... but am feeling well and truly fecked!!!!

Went for NCT, and (surprise, surprise) failed on.......... emissions. Feck sake.

Tester said car was in fantastic condition, and was really sorry, but there was nothing he could do about it. He asked if I had the car warm before the test - I told him I had booted it over to the centre, but they had kept me waiting 30 minutes before testing, so it had obviously cooled. Any way, (I am getting to the point here) high idle pass is approx 3.50, whereas I was at..... over 9! He said it was REALLY high. I left it in to a local garage, and he called back soon after to say the REAR lambda (oxygen) sensor was broken (as in physically broken), and needed to be replaced before he could investigate further. He tried to get a replacement but said none of the motor factors he tried had one, so asked me if I could source one. It's the sensor after the cat. Anyone know where I can get one of these? I sent the following links to him, but he said it is NONE of those shown. He described it as being pencil-like, and bolts onto the cat? Does this make sense? I can't find and pics on line of the part. Am going back to visit him tomorrow or Friday and will see if I can get a photo of it.


https://www.mx5parts.co.uk/advanced_sea ... gen+sensor

https://www.micksgarage.com/d/lambda-ox ... 8/products


Sorry for the long ramble - and thanks in advance.

Graham.

As much as it kills me to say it, go to a main dealer and see what they can offer... if yours is an import, be prepared to suffer the bullshit that they're likely to throw at you..but stand your ground...
Went to a main dealer in Kildare before for a small part..can't remember what for now, but spun them the story that I had used an import as a donor vehicle for a track car build, it shut them up very quickly!!
Good luck!

P.S. it was for a rocker cover gasket..just remembered!!

John

Graham, I’m pretty sure the sensor after the cat is only the cat overheat temp sensor and has absolutely no influence on emissions .
The only O2 sensor for emissions is up near the manifold, have a search on YouTube how to test a single wire O2 sensor with your new multimeter

This might help
https://www.2carpros.com/articles/how-t ... -02-sensor

Having viewed the item today and did some googling, I fear this may be the only option, John.

Just in case anyone knows where to get one of these, here are some photos. Robert, would you have any thing that would suit?

The sensor itself is IN, not after, the cat. It's more of a probe, and when it was removed today it was covered in soot, so clearly the system isn't doing (can't do) it's thang. Car is over-fuelling, hence the sky high readings. I need to replace this first, to see if the emissions come down - and if not, then at least this is ruled out.

Here is the cat, with the bracket attached


The probe that is now broken


Where it attaches to the loom/system


The probe itself, removed from the bracket inside the cat - really sooty!


The open bracket into the cat



If anyone has had to replace this before - please let me know where you got the part!

As before - any help is greatly appreciated.

Thanks,

Graham.

This is the temp sensor
http://www.autolinkmx5.com/cat-heat-sen ... 3293-p.asp
Google it’s use before spending anything though.

That sensor has nothing to do with emission controls. It is a fuse like probe that when overheated (failed cat) triggers a warning light.

Post the readings

Thanks for the replies - And we'll done on finding the desired part Pops?i thought I'd googled the bayjezuz out of the internet and was having no luck).

Perhaps better news is that that items actually seems redundant.

I don't have the fail sheet with me at the moment, but know it failed on the High Idle CO % volume reading. Above .30% is a fail. Mine was over .9!!!!

Thanks again for the replies- and any other ideas on a cure are very welcome.

Graham

Did you test your O2 sensor? Seems they can “go bad” over time.
Thinking of getting one myself as my car is doing roughly 20mpg.
https://rover.ebay.com/rover/0/0/0?mpre ... 2639066927

yeah that's def the cat overheat sensor, you can zip tie up that cable and forget about it, as said above it does nothing but trigger a warning light on the dash.

O2 sensor for the MK1 MX5 is pretty generic "1 wire" sensor, you should be able to pick one up in a local motor factors or just here :
http://www.autolinkmx5.com/oxygen-lambd ... -122-p.asp

We have some of the sensors here but the first thing I would suggest is NEW temperature sensor at rear of engine as its signals the ecu as to eng temp and can cause overfuelling ,high emissions.Been there ,done that, several times , and it worked mostly...

It tell you the cat is bollixed. Nothing more. It's a fuse. When it melts it throws up a light.

Thanks for the replies and help - it'was much appreciated. And as from 5pm today I could change the title of this from ARSE to "YEEEEEES!!!!!". Thank feck - passed the retest with flying colours (and it feels GREAT).... I'm a happy boy this evening. Left the car in with a guy who sorted things out (seems the lambda sensor and Cat were fine). At the initial test the CO reading was over 9% (below 3.5% is a pass) and today CO was 0.26%.

So, what was the issue that he sorted?