Hello, Could someone give me some ideas on why my car failed on the emission test when she went for mot.

This is what is says

Fast idel test : Fail

Engine speed : Pass
2500-3000rpm 2844rpm

CO: 0.20%vol
0.75%vol Fail

HC: 200ppm vol
32ppm vol Pass

: 0.970-1.030
1.024 Pass

Natural Idle test : Fail

All that means nothing to me so any advice would be really helpfull!

 

This is the typical scenario for emissions failure i.e. too high a CO content on the Fast Idle Test.

First, you defo have a catted downpipe (or at least one in the centre section), yes? (I'm guessing so, because the HC ppm content is only 32!).

Things to check in order of ease/expense:-

- check for very clogged air filter
- check Lambda sensor's output voltage is correct i.e. that it's performing properly
- check spark plugs for fouling/cracks/general overall condition - clean them thoroughly if okay
- whiilst checking plugs, check condition of coilpacks and/or HT leads (as appropriate for your MY).

 

but the lambda is a pass at just over 1.0
I would suggest the cat is fooked, personally

find a friendly garage, or a mate with another CAt you can use

 

"1.024 Pass"

Doh! Overlooked that...

 

make sure you'r mass airflow sensor is working coreectly (a fast, or otherwise poor quality idle wouild point to the MAF too) and you are running it on premium fuel. low grade fuel or/and a dodgy MAF can lead to the ECU getting a bit upset and if it starts detecting the on-set of det it will start over fuleing and retarding the timing to protect the engine, but at the same time this will make it burn less efficently and alot less cleanly


Hope you get here through without too much hassle, my first MOT with a scooby is coming up soon too!

Ash

 

As I normally run a GEMS ECU I do have fun at MOT time so a bit of slight of hand is usually required. One other thing is to take the car for a GOOD blast before hand to get everything upto temp and cleaned out. Also try to ensure that the emission test is done on arrival, take the other half with you and get her to ring to say you might be a few minutes late due to traffic. Turn up 5 mins late so everything is HOT.

 

Ok thanks, Well i've done these things :-

*I've had the plugs changed about a month before she went for mot.
*As for the lambda sensor some else told me that because when she is hot she seems to misfires
* I checked the air fillers last week because i was cleaning the mar sensor and the filter looks clean
* As for the coil pack and HT leads I dont know! The garage told me not to bother changing them. Maybe I should have!

I'm completly new to all this stuff.