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Old 29th June 2019, 22:59   #1
Madderz
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Default curious exhaust emissions behavior

So today I've been servicing my mates '09 Berlingo van, and as I'm a curious fellow i thought I'd fire up my gas analyser to get some kind of idea what's going on inside the engine 'before and after' the service.....

Before we were getting an efficiency ratio of 1.4 (very bad lol) and 2400 ppm of C0.
After we got a ratio of 0.8 and 1200 ppm to start with.... However!
After 4 minutes sat at 2500rpm all readings suddenly dropped off, and not by a little bit, by miles!
Suddenly we had a ratio of 0.0004 (brilliant verging on unbelievable) and 28ppm, that's 28 parts per million!

As we were both struck with the sudden difference we did the same test on my '11 VW Caddy van, and it did exactly the same thing after the same 4 mins at 2500 rpm.


What's going on?!
Might try the ZT tomorrow to see what happens
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Old 29th June 2019, 23:42   #2
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Ha! So Peugeot had the same emissions fixing programme that VW got slated and fined for? Once your vehicles "realise" that they are on an emissions test, the ecu re-sets everything to produce ultra low emissions readings which do not represent true performance under load!
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Old 30th June 2019, 10:49   #3
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I thought as well a software program to help with emissions.
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Old 30th June 2019, 11:27   #4
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Simple answer is after a few minutes the cat has got hot and doing what it should and also the engine has warmed up and gone into closed loop fuel control rather than running on a richer mixture.

Emissions should always be done on a "normal" operating temp engine anyway.

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Old 30th June 2019, 17:22   #5
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Quote:
Originally Posted by Madderz View Post
What's going on?

The catalytic converter got up to operating temperature.


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Old 30th June 2019, 21:32   #6
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Ah, I think I get it then. It's kind of the equivalent to crusing at 70 rather than the constant variables involved in accelerating and changing gear to get there.

I'm used to big oil boilers where things level off to a constant, not suddenly tailing off to next to nothing

Cheers guys
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