Emissions MOT failure HELP!

[muttsnuts73]

HI all,

My beloved 98 MGF VVC has failed its MOT on several things, a few I can sort out on my own, but I need help with diagnosing the Emissions failure.

Data from the print out is as follows:

Fast idle-
CO=205% Fail
HC= 533ppm Fail
lamba=1.060 Fail

Second Fast Idle
CO= 1.29% Fail
HC= 111ppm pass
lamba=1.027 Pass (just!)

Natural Idle test
CO=0.50% pass (just)

The MOT inspector tried it a couple of times.

Any help on this would be very appreciated.

[hearselover]

Mine did the same, it was a duff cat. Have you had the EWL light pop on so you can get a code.

Ash

muttsnuts73 said:

HI all,

My beloved 98 MGF VVC has failed its MOT on several things, a few I can sort out on my own, but I need help with diagnosing the Emissions failure.

Data from the print out is as follows:

Fast idle-
CO=205% Fail
HC= 533ppm Fail
lamba=1.060 Fail

Second Fast Idle
CO= 1.29% Fail
HC= 111ppm pass
lamba=1.027 Pass (just!)

Natural Idle test
CO=0.50% pass (just)

The MOT inspector tried it a couple of times.

Any help on this would be very appreciated.

Edited by hearselover on Friday 23 April 16:52

[muttsnuts73]

No warning lights at all, Ill take the cat off and have a good look at it.

Cheers mate.

[perdu]

muttsnuts73 said:

No warning lights at all, Ill take the cat off and have a good look at it.

Cheers mate.

check the voltage out of the lambda too

the lambda makes a voltage inside according to the amount of O2 it senses in the exhaust stream

if it breaks down it sends the wrong signal voltage to the ECU and lets the fuelling go all to cock

The wrong fuel kills the cat, it aint designed to drown in excess petrol

I'd advise a diagnostic check if you have a garage you can trust, just a measure of the O2 sensor voltage output will tell most of the story I found (should be low not over a volt A/C usually)

My missus's Monjo had this and it just took a replacement HEGO (ford use heated O2s) to sort it

like £20 instead of £C to sort it (scrap yard HEGO from newer Monjo)

It isnt always the CAT which beggars things up some times

no easy fixes

I'm no expert but it does bear thinking about I think

[hearselover]

Ive had the pre cat 02 sensof go on my ZR 160 before adn that throws a fault code up and causes erattic idling on startup, ive also had the cat go on my MGF which didnt throw a code up and did not cause any other problems apart form emissions failiure. If you find it is the cat dont buy a cheap universal or pattern part its just not worth it in the long run, similarly for the 02 sensors the universal ones are cheap but wont last anywhere enar as long as the oem part. If you are keeping the car fit decent parts.

Cheers

Ash