MOT fail! - emissions. Any suggestions would be appreciated!

[..lee..]

When to do the test
It Is recommended that the engine is tested as soon as possible after driving on the road
.

B. Vehicles first used on or after 1 August 1975

1. Check that the analyser probe can be inserted into the tailpipe.

2. Use a suitable exhaust gas analyser to
determine the proportions of carbon monoxide {CO) and hydrocarbons (HC in the exhaust gas over a period of at least 5 seconds at idle.

Note: Any residual hydrocarbons (ie those indicated by the analyser when it is sampling only clean airj should be deducted from the HC reading obtained from the vehicle.

Note: If a vehicle meets the CO requirement at its normal idling speed but fails the HC check, re-check the HC level at a high idle speed of 2000rpm. If the HC reading is 1200 ppm or less, the vehicle will meet both the CO and HC requirements.
. the CO requirement must be met with the engine running at its normal (low) idling speed
. do not use a cold start/cold running mechanism to achieve a high idle speed. Instead, apply light pressure to the throttle pedal.
. HC not applicable to Compressed Natural Gas (CNG) fuelled vehicles.
B. Vehicles first used on or after 1 August 1975

1. The emissions cannot be measured because a tailpipe accessory is fitted which prevents Insertion of the analyser
probe

2. The exhaust gas contains
a. a carbon monoxide content
exceeding the limit for a continuous period of 5 seconds

b. a hydrocarbon content exceeding the limit for a continuous period of 5 sec

[Red Westie]

Ian...missed the CU....but that doesn't make any difference and what I said stands.

Martin

[eddie.eagles]

[quote="Red Westie"]Ian...missed the CU....but that doesn't make any difference and what I said stands.

Martin[/quote

is there a difference then between the engines with regard to your answer, I haven't a clue?

For those of us looking at info/answers with limited technical knowledge, any posts that have 'corrective' answers (Ian Hulley) is confusing......It would lead readers to believe that the engine type you quoted and the answer you gave is inaccurate. Is Ian right or you Martin or have I misunderstood Ian's post and that it makes no difference to your answer but Ian was merely pointing out your dreadful mistake?

[CovKid]

No difference. Emission tests (and how strict they are) are based on when vehicle was manufactured. So both are right

[simony]

were i take mine they dont even check emissions they said on vehicles this age they dont bother unless they smoking bad !

[peteabbott]

This sounds a bit wooly depending on the garage you use. I take my old 93 1.8 petrol cavalier to a pretty good well known garage for its MOT and they do not check exhaust gas as they say it is too old. Dont think I will question it though. Hope your next visit will have a good outcome.

[The_blue]

Finally got a pass on original results but only by telling him i was filling in an appeal form!

it would have failed on the retest, retest! Got CO to .45% (10X under) but HC now 2000+ It's not burning efficient.

Going to try some new plugs.


I'm hearing a popping sound still on idle. It's very slight and when i stuck the colour-tune plug in the 2nd cylinder i could see the flame change in time to the pop. Either a fouled plug lighting the mix late or a valve open i think? The exhaust is finally sealed so it's not that.

Any better ideas?

Ah, things were going so well