Nearly failed MOT on emissions?!?!

[paulo]

Today I had to take my car for its first MOT. Everything was going well (as expected) until the emissions test.

The Lambda was reading high (by quite a bit).

The guy ended up leaving it, doing so other things, and then retesting it. Luckily, everything was ok the second time around.

Now, should the emissions still be acceptable when running in sports mode? The reason I ask, was that before the test, the guys where playing with the sports mode, and revving it a bit. Could this have thrown the readings, even after putting back to normal mode before the test?

Anybody else had problems with emissions?


Paul

[PetrolDave]

I had my first MOT last week and sailed through the emissions tests no problem.

Revving it should, if anything, be a good thing since it will clear out any soft build-ups in the engine/exhaust (remember that the MOT test for a diesel REQUIRES the engine to be run to the limiter before the emissions tests are made to clear out smoke particles etc.).

[S2tuner]

Cats were probably cold, which explains why the car failed on the first test.

[scaghead]

my motor has just failed the emissions test on lambda.....pass is min of 0.970 to max 1.030..my reading was 1.9 to 2.04 slightly high ..... co reading was 0.02 and HC was 31 ppm these two readings were fine... any ideas fellas

[pad125]

Scaghead, Is it in with the dealer for the MOT? They'll probably point to the Mass Air Meter first and want to change that, after that.................it could be a world of hurt!!

[neckarsulm]

scaghead, I'm surprised that it's running so lean and yet spot on with CO and HC

[karl]

Cats were probably cold, which explains why the car failed on the first test.

Cats? What Cats?!

[scaghead]

scaghead, I'm surprised that it's running so lean and yet spot on with CO and HC

yes that is the thing that is a bit confusing.. at low rpm it was at its worst 2.04 as it was reved up to 4000 rpm it feel a little to 1.94.. am i right in thinking if it was the lamda sensor it would mess with the co reading??

[scaghead]

Scaghead, Is it in with the dealer for the MOT? They'll probably point to the Mass Air Meter first and want to change that, after that.................it could be a world of hurt!!

patrick i got the mot done at a friends garage.. the world of hurt dont sound to nice i have had it re-mapped but that was nearly two years ago so i have ruled that one out as it was ok last year..

[neckarsulm]

Standard or Milltek? I'd say possibly post cat air leak in exhaust but could be other things
Do you have Co2 and O2 readings as well?

[scaghead]

standard exhaust system fella.. would it be a case of i dont really use it that often and it needs me to give it a bit of a tanking to clear it out a little the op had the same issue but it self cured while he was there ...i will take it back monday and give it another go... if not a trip to the good old dealers for me..
the only readings i have are those above fella...

[neckarsulm]

It's quite normal for a car to take a couple of goes to get through the emissions test especially if it's been around town a lot.
I'd appreciate Minhea's (S2tuner) view on this but I always thought cold cats (but engine fully up to operating temp) would increase the CO as well as mess up the lambda.

[Dom81]

It's quite normal for a car to take a couple of goes to get through the emissions test especially if it's been around town a lot.

Interesting. I worried reading these posts, so dug out my latest (and so far, only) emission results from an MOT test in March. At fast idle they were -

CO 0.01% (limit =< 0.20%)
HC 8ppm (limit =< 200ppm)
Lamda 1.002 (tolerance 0.97 - 1.03)

No comfort to Scaghead or the OP, but since the car is low mileage and crucially does nothing around town, I guess it might be that the stop / start and cold runs contribute?

[scaghead]

It's quite normal for a car to take a couple of goes to get through the emissions test especially if it's been around town a lot.

Interesting. I worried reading these posts, so dug out my latest (and so far, only) emission results from an MOT test in March. At fast idle they were -

CO 0.01% (limit =< 0.20%)
HC 8ppm (limit =< 200ppm)
Lamda 1.002 (tolerance 0.97 - 1.03)

No comfort to Scaghead or the OP, but since the car is low mileage and crucially does nothing around town, I guess it might be that the stop / start and cold runs contribute?

you could be right there fella. i will see what happens on monday

[sonny]

Was it a dealer or Indy you had the MOT done?