Help 997.1 GT3 MoT fail - high lambda?

[BertBert]

The garage doing my MoT test can't get the emissions in spec, the lambda reading is high. He can't see anything awry to cause it, but at the moment it's a fail.

Anyone had this, or got any clues to what might might be?

As far as I know, apart from the sharkwerks rear box, it's all standard.

Cheers
Bert

[PM3]

google thinks ...exhaust leak.

[BertBert]

that is what the MoT man thought it might be, but can't find anything.

[boxsey]

With the air cooled cars (964 onwards) the advice (from Unit 11) was always to ensure that the engine was up to operating temperature before doing the emissions tests. Maybe the same applies to 996/997 GT3?

[Dammit]

If it's got 200 cell cats then (in my experience) it won't pass until it's properly hot - as in, been driven hard on the road. They'd never get hot enough just revving it up when parked.

[PM3]

BertBert said:

that is what the MoT man thought it might be, but can't find anything.

I know, its too easy that way. I'll presume he also ( somehow) eliminated the possibility of a lambda sensor itself starting to fail. it certainly wouldn't be the 1st car to have that happen, even if they can last "life" of car ..and sometimes early life fail .
I'll dip out as have reached the short limit of my knowledge of engine management/pollution control systems.

[Chubbyross]

How friendly are you with the people carrying out the MOT? I know my garage often struggle to get my 7.1 turbo through the emissions test. They say they see this a lot with powerful cars that aren’t used for long periods. My mechanics are extremely sympathetic and have to test and retest several times, often allowing me to take the car off for spirited runs before trying again. It always scrapes through but everything needs to be seriously hot before it passes.

[MrC986]

Chubbyross said:

My mechanics are extremely sympathetic and have to test and retest several times, often allowing me to take the car off for spirited runs before trying again. It always scrapes through but everything needs to be seriously hot before it passes.

OP, I’d try the “Italian tune” method as outlined by Chubbyross in the first instance (give it a serious spanking on the way there and ideally have a first thing slot so you aren’t waiting around) and if necessary when it’s due it’s next test ask them to just put it on the emissions as a pre-test so you can hopefully prevent another failure on it. As an aside it shouldn’t have lambda sensor issues at that age IMO.

[pete.g]

A faulty lambda sensor will throw a code, as will a faulty EGR. Spark plugs or a vacuum leak would lead to fluctuating idle, misfiring or rough running.

Have they told you the reading and how close/far away you are from it?

If you aren't using a premium fuel, then get a tankful and burn through most of it at higher operating speeds and try to get tested whilst it is still warm.

[WindyM]

I'd echo a few of the previous suggestions.
I had a 997.2 T4S which had a lambda sensor go but it threw a check light and went into the limp home mode, so I doubt it's that.
My son's Golf 1.4 S failed last year with horrendous emissions. I filled it with Shell V-Power (he used Sainsbury's unleaded - typical student) and gave it an Italian tune-up before the re-test and it turned in "the lowest figures we have ever seen". Within 1 day! I wonder if their machines are variable?
Good luck and please let us know how you solve it.
(I have a 997.1 GT3 now but it's passed the last two MoTs no problem.)

[Dan911]

Sometimes the cats need to be hot, take it for a quick blast right before the MOT.

Dan

[BertBert]

Thanks all. The range is 0.97 to 1.03. the best this morning was 1.04. got it much hotter this afternoon and all was ok.

Thanks all for the help!

Bert

[Chubbyross]

BertBert said:

Thanks all. The range is 0.97 to 1.03. the best this morning was 1.04. got it much hotter this afternoon and all was ok.

Thanks all for the help!

Bert

There’s proof that the Italian tune-up does indeed work. I only drive my car every two or three weeks. I was advised to use it every day before next year’s test and give it a thorough spanking on the way to the garage.

I’m glad yours got through ok.