Mondeo NCT emissions fail

DerMutt

Hi folks,

Yes, it's yet another NCT emissions thread - hoping someone can tell me if it's the cat or if there's something else I need to look at.

Car is a 06 Mondeo 1.8 Petrol.

Cat was replaced with a cheap one a couple of years ago when the original collapsed internally. I've since read that cheapos may not last that long, hence my prime suspect...

Dash check engine light had come on, so I pulled the battery neg for half an hour, gave it a dose of Dipetane, drove it hard for a couple of days and hoped for the best. Fail!

I asked the NCT man if it was the cat, he said it was running rich.

Here are the results:

Engine/Oil Temperature 86 C

Low Idle (820 rpm)
CO 0.43 vol% Above 0.30 % FAIL/REFUSAL
HC 218 ppm

Lambda: 1.0

Low Idle (2,750 rpm)
CO 0.63 vol% Above 0.20 % FAIL/REFUSAL
HC 203 ppm Above 200 ppm FAIL/REFUSAL

Couple of days later check engine light is back on. The cluster test says "dtc none".

I've ordered one of those OBD gadgets so I can have a closer look. Any ideas in the meantime?

Thanks in advance,
D

Squatman

if its running rich, then your not getting the correct air to fuel ratio. Running rich for extended periods can deteriorate your catalytic converter, however, the catalytic converter will not remove excess emissions when its running rich. you should notice that the revs are not correct, car is spluttery and sluggish, with reduced power.
some suspects for running rich are
Cracked pipes on air intake
MAF sensor - dirty or broken
O2 sensor - someone else will probably diagnose this better than me bases on NCT emission results

DerMutt

Thanks Squatman.

So, it's adding fuel to make up for the extra air? Does that mean it's probably killed the cat anyway?

I had a root around there and can't find any cracks/leaks in the air intake.

Found a guy called Craig on YouTube who has a similar car and seems to have done all sorts of stuff around his engine regarding fuel and emissions. It turns out I don't have a MAF but I do have a T-MAP sensor and an Idle Air Control Valve which I can take off and squirt with cleaner and see if it helps.

I did notice a slight sluggishness when accelerating or going uphill at 2,500/3,000 rpm alright.

martinr5232

There is an engine breather pipe in under the inlet manifold that splits and causes it to draw air. Is your car ticking over higher than normal ??

DerMutt

martinr5232 wrote: »

Is your car ticking over higher than normal ??

Not that I've noticed. I just had a look at the last NCT in 2015 and it was idling at 920 then!

There is a small rubber pipe coming out through the manifold right in the middle. Is that the one? I gave it a tug and it's moving fairly freely. I take it that means it's split - and to get at it the whole manifold has to come off!

Dose

martinr5232

DerMutt wrote:

There is a small rubber pipe coming out through the manifold right in the middle. Is that the one? I gave it a tug and it's moving fairly freely. I take it that means it's split - and to get at it the whole manifold has to come off!

Yeah manifold has to come off to replace. Not sure if you can even reach it with manifold still on its a while since i changed one.

With a reading 1.0 it's not running rich anyway so not sure what the tester meant. If the second decimal is not a zero (1.00), it could be running a bit lean though. The permitted range is 0.97-1.03 but if the actual reading is not 0.99X-1.00X the car will most likely not pass as the catalyst won't be able to reduce the emissions correctly.

With OPs given reading I would say that it's time for a new, and this time a better quality, cat. That aside the HC values are higher than expected, does the engine burn any oil? Are there any signs of misfire?

vandriver

Fabia 1.2 htp
Don't really need ANOTHER thread,so here are my readings from this morning...
Low co .84,HC 300
High lambda 1.02 co 1.95 HC 272
There is a smell of exhaust in the cabin,and it's definitely down on power.
Thoughts(apart from a match and a gallon of premium)

vandriver, as that's one of the famous 6v 1.2 cyls I would start with the compression test to rule out the burned exhaust valve(s) as the cause. Especially if there are persistent misfires on one or more cylinders.

Otherwise start checking for leaks on both inlet manifold and the exhaust system before the cat.

DerMutt

Maybe he could smell it running rich samih? Engine doesn't use much oil. Only hint of anything was when accelerating, more on this below!

My scan tool arrived so I hooked it up and lo and behold there is a code - P0420 Catalyst System Efficiency Below Threshold... Had a look online and set the OBD reader to check the O2 readings. Both before and after the cat are more or less the same, so the cat definitely seems to be dead.

I took it out for a test drive with live scan data, got it warmed up and when I planted the right foot going uphill the engine spluttered and nearly died about 2,500/3,000 rpm and both O2 sensors dropped flat no voltage. The freshly cleaned MAP sensor values went through the roof! Vacuum leak?

Waterson

Low voltages on oxygen sensors show a lean mix, assuming the sensor is reporting correctly. You're in the market for at least a new CAT. The PCV pipe is only accessible after removing inlet manifold, but it's not a massive job, did one myself last week, an hour's work altogether.

jdh1987

vandriver wrote: »

Fabia 1.2 htp
Don't really need ANOTHER thread,so here are my readings from this morning...
Low co .84,HC 300
High lambda 1.02 co 1.95 HC 272
There is a smell of exhaust in the cabin,and it's definitely down on power.
Thoughts(apart from a match and a gallon of premium)

New o2 sensor. Them 3 cylinder engines always go that way same as the polo.

vandriver

jdh1987 wrote: »

New o2 sensor. Them 3 cylinder engines always go that way same as the polo.

New valve guides and seals,new chain,big bill!

DerMutt

So, after being fleeced by main dealer I stripped the manifold (and a couple of knuckles), took me a bit more than an hour Waterson! PCV pipe was perfect As the parts were special order and can't be returned I replaced them anyway. Had a look in the oil separator as I was in there, no sticky mess so all good there. Ordered a new cat from Micks Garage and seeing as it's nearly due a service I'll change filters, oil, plugs, etc. and see how she goes.

One thing I came across is the possibility of a weak or failing fuel pump which might fit with going lean...

rex-x

DerMutt wrote: »

So, after being fleeced by main dealer I stripped the manifold (and a couple of knuckles), took me a bit more than an hour Waterson! PCV pipe was perfect As the parts were special order and can't be returned I replaced them anyway. Had a look in the oil separator as I was in there, no sticky mess so all good there. Ordered a new cat from Micks Garage and seeing as it's nearly due a service I'll change filters, oil, plugs, etc. and see how she goes.

One thing I came across is the possibility of a weak or failing fuel pump which might fit with going lean...

Its not going lean though, your lambda is 1.0 which is perfect. Also a lean reading would have less CO. It looks like your cat is indeed dead but judging by the hc readings the engine isnt running too great, may be poor compression or old spark plugs/coils/ burning oil etc. The burn is not clean as it could be.