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weird values on inspection...fixed?

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EuroGSTSpyder

20+ Year Contributor
1,171
2
Feb 18, 2002
Stockholm, Europe
Ok I went for yearly inspection and I failed emissions. My lambda value were up the roof.

I also checked my logger and the LFT was 137% . I checked up on things and found my ex manifold had 4 broken bolts + lots of cracks in it.

I switched and put on my EVO III manifold and now my LFT is back at 100%. Could this have made my lambda values on inspecition go way high?
 
Yep, An exhaust leak pushes out exhaust and sucks in air. if unmetered air enters the exhaust, then the O2 sensor sees a "lean" condition and would add extra fuel, thus a higher fuel trim number. Removing any exhaust leak before the O2 sensor will allow proper fuel control.

Lambda would be high because the PCM sees a lean condition and is adding fuel to correct. Same thing happens with a defective O2 sensor that will not indicate a rich condition. I assume the Lambda value was from the inspection report. The value is of little use if there are any exhaust leaks- Since the Lambda is inferred (in most all analyzers) by a formula and the tailpipe gases: CO, CO2, O2, HC (and sometimes, but not necessarily NOx). If you add extra air into the sample that was not used in the combustion process, you can throw the number away. All that extra oxygen skewed the number lean.
 
Yepp lambda value was from the inspection.
Here they test the CO value at idle + at 2500 rpm. Those values were perfect.
My HC value was 139 of allowed 100
The lambda was 1,27 out of 0.97-1.03 allowed.

What speaks in favour of the thoughts I had is that before the swap of the manifold the LFT was 137%, and now when I swapped it out its back to 100%. I do not know how much the 37% added would affect the final value of the lambda though but it must definitly affect it in the wrong way.

I will have to go back next week and see how the values are now though.
 
I'm not sure what "Perfect" was, but Lambda at 1.27 means that the mixture was 27% lean as measured through the tailpipe. The vehicle could compensate for this and run rich, and the catalyst will eat up most of it and leave you with good numbers, but easily not as good as it could be. The catalyst converts CO more readily than HC, which could be why your HC is still on the high side. Of course without looking at the vehicle and getting pre-cat numbers it's speculation until you get a new test and confirm!
 
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