MOT emissions failure where do I start ?

Hi Guys and Gals

I have just put my puma in for its MOT I did all my prep work changed the wishbones, replaced the rear subframe bushes, cv boots, power steering pipes, rear flexi hoses, welded the the rear chassis and changed three tyres and yes all was good except for it failed on the emissions not just on one but all emission tests idle and fast idle. Problem is what do I do first, obviously I have no way of checking any work that I do until I put it in for a re-test, which could fail and then do something else fail again etc. Is there a common fault the car runs as sweet as a nut doesnt burn oil and has done 103,000 miles. Any ideas guys would be great.

Possibly a Lambda sensor/s problem

Possibly best to get the car plugged in and scanned for faults

Good luck with it :thumbs:

Unplug the lambda connector nd check that the pins aren't corroded. That would be one of a few things that would mess up your readings. Clean contacts wit wd40 or electrical contact sprqay. ?Next is a fault code read. Lambdas do fail.
You can check the resistance of the lambda sensor preheater across 2 of the 3 pins from memory it should be 13 ohms. but search for previous info i posted about this

Also if you cant find any faults with Lambds/lambdas, then your Catalytic converter might be goosed, so might need swapping out. Do you know how far out your readings were?

Check pins as DOH suggested, a good squirt with contact cleaner never goes a miss.
Failing that, before shelling out for a dia read out, a bottle of £10 Forte petrol treatment from any respectful garage accompanied with a good (20+ mile) motorway clean out has been known to tell the emissions machine a joke second time around.

Obviously STP etc ect additives are available but Forte is the dogs huckleberries

spoke to a ford dealer today and he suggested i changed the cat and the eco sensor (lambda) not surprised at £600 for a cat and £175 for the sensor. I know I can get these on ebay for £90 and £25 but are they any good anyone used an aftermarket cat. Anyone got an idea of what a scrap cat is worth recycled as I believe some places buy them off of you.

Every scrap yard will buy a cat off you, prices can vary from 25 notes up to 150, IF it has the right materials in it and or is an original

neilus123 - what was the outcome? Was it the CAT?

On Wheeler Dealers Ed China successfully brought down the emissions on the XK8 Jag using a machine which input chemicals into the engine in place of the normal fuel and it cleaned out all carbon from the piston chambers back to the end of the exhaust system. I had never seen this before but at a reasonable price it could be worth a punt .

Later cars throw up an engine management light if the cat has gone. not on the early models though as they only have 1 LAMBDA before the cat. most likely to be CAT or one of the lambdas as previously stated. Wouldn't recommend initially de-coking the engine as it wont fix either of these problems, might be a good idea after the main problem is fixed.

First step diagnostic, around £35-40 from a local garage, otherwise you are shooting in the dark.

I had my cat changed last week as EML was up, got it diagnosed and second LAMBDA flagged up. further investigation, signal from second lambda was reading similar to first so pointed towards cat. part was £130 plus an hours labour.