Aston V8 Failed emissions test

Aston V8 Failed emissions test

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dad666

Original Poster:

6 posts

37 months

Thursday 25th February 2021
quotequote all
Hi
My 2007 V8 vantage has just failed it's Mot. The Lambda reading was too high.
There are no error codes being thrown up and no warning lights showing on the dash.
Any ideas would be welcome.

paintman

7,669 posts

189 months

Thursday 25th February 2021
quotequote all
Might help to say:
What diagnostic machine has been used to check for any codes?

What were the rest of the emissions figures?

Any leaks in the exhaust system - common cause of high lambda reading & had that on Mrs p's 307 last year. Small hole in the rear silencer.

dad666

Original Poster:

6 posts

37 months

Thursday 25th February 2021
quotequote all



The code reader was just a generic code reader. It did pick up that the exhaust valve circuit was inactive but that has been like that since I bought the car and has always got through all previous MOTs at the same MOT station. There had been a loose clamp on the exhaust but even after it was tightened the readings were still too high and we couldn't find any other leaks with the car up on the ramp.




Edited by dad666 on Thursday 25th February 14:45

Cornwall1

91 posts

53 months

Thursday 25th February 2021
quotequote all
dad666 said:
Hi
My 2007 V8 vantage has just failed it's Mot. The Lambda reading was too high.
There are no error codes being thrown up and no warning lights showing on the dash.
Any ideas would be welcome.
Try posting this in the Aston Martin section, lots of knowledge on there.

stevieturbo

17,229 posts

246 months

Thursday 25th February 2021
quotequote all
dad666 said:



The code reader was just a generic code reader. It did pick up that the exhaust valve circuit was inactive but that has been like that since I bought the car and has always got through all previous MOTs at the same MOT station. There had been a loose clamp on the exhaust but even after it was tightened the readings were still too high and we couldn't find any other leaks with the car up on the ramp.




Edited by dad666 on Thursday 25th February 14:45
I would question the validity of those numbers, as CO and HCC are too low.

But a lot does also suggest an air leak in the exhaust, or flawed test method allowing air to be sampled too

dad666

Original Poster:

6 posts

37 months

Thursday 25th February 2021
quotequote all
Thanks. I’ll get it up on the ramp again and go round every joint again. There is no rust in the system so holes are unlikely.

paintman

7,669 posts

189 months

Thursday 25th February 2021
quotequote all
Tightening up a loose clamp may not have stopped it.
Plenty of sealing paste on joints after the Lambda?

dad666

Original Poster:

6 posts

37 months

Thursday 25th February 2021
quotequote all
Will do.

robwilk

818 posts

179 months

Friday 26th February 2021
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put fuse 22 back in and close the exhaust valves , worth a try. Its always a good idea to keep them moving anyway

dad666

Original Poster:

6 posts

37 months

Friday 26th February 2021
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I'll try that as well thanks.

Frenchenstein

5 posts

64 months

Monday 1st March 2021
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Is the vts getting regular lambda fails? It could be the analyser suffering a sensor fault; happened to us five or six years ago, and a fortnight ago (Boston Analyser).

dad666

Original Poster:

6 posts

37 months

Monday 1st March 2021
quotequote all
I’m afraid not. My old Landrover V8 went through on the same machine no problem.

stevieturbo

17,229 posts

246 months

Monday 1st March 2021
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Still doesn't rule out a problem or user error.

The numbers do not add up.

lexusboy

1,099 posts

142 months

Monday 1st March 2021
quotequote all
With the other readings being low it says to me you have an exhaust leak.

Get a rag of something and hold your hand over the tailpipe (without burning yourself) and see if you can head any more obvious leaks. May need another person whilst you take a look.

Only do it for a few seconds at a time though