MGF Emissions fail

[dave21478]

I took the MGF for its CT inspection and it shat the emissions test - I havent got the faintest what I should be looking at to fix this.

 

Idle CO - 0.80%

Fast CO - 0.76%

Lambda 1.020

 

I never got the reading but "the other one" which I assume is HC was also too high.

I dont know what the max limits are but I believe similar to UK.

 

Yes I did remember to put the CAT back on it.

 

Service? oil is pretty recent. Sparkplugs? Fuel filter?

 

Also - is there any MGF specific way to test these. He put the probe in the right hand tail pipe, which emits less gass than the left....if that makes any difference?

 

 

Everything else passed ok....advisories for minor corrosion on a rear brake flexi fitting, minor play in rear suspension, and for corrosion to subframes and boot floor. The headlights were a really borderline pass, but I think I need to take them apart again and clean up the internal glass as its gone opaque.

 

[paulplom]

What about a good hard italian tune up and a dose of cataclean?

 

Sent from my SM-G903F using Tapatalk

[scaryoldcortina]

You often have to plug one of the exhausts when doing a F, otherwise the lambda reading goes to cock.

 

Everything was in limit last time I tested that one though, so you might have a bad lambda sensor, or maybe a small misfire.

[dave21478]

Cheers - Yes I looked out the last MOT and it had a super clean pass.
Is there a realistic way to test a lambda sensor or is it best to just replace it anyway?

[Barry Cade]

Get it on an OBD with a co display and see if the Lambda is switching- Lean/rich/lean/rich.. If it's fairly static,replace it.If it's switching correctly,then it's either fuelling or the CAT itself. If you've had the CAt off and run it that way, it's worth doing a reset to base settings and take it for a thrash to relearn idle etc.

 

HC too high could indicate too rich,so too much fuel or a missfire etc. This can kill the cat if not sorted quickly. Lambda reading isn't too bad

 

My take, going on past experience with the K, and your readings... Cat's U/S.

[tommotech]

To know what is truly going on you also need to know the O2 reading, you could have an air leak after the throttle butterfly but I would expect other side effects.

 

You do need to see the raw signals fluctuating from the oxygen sensor to check sensor function.

 

Good luck!

[Guest Lord Sward]

A good dose of fuel additive into some premium/super unleaded and a damn good thrashing.  Then when its hot, take it for a test.  

[scaryoldcortina]

Last test was done hot, they are always crap when cold. cat was new a year ago.

[DodgeRover]

Is there not an option to pull the probe out and stick it in something else whilst having a fag on the CT then? Seems remarkable strict considering some of the chod I've seen imported with fresh ones...

[dave21478]

Thanks for the help so far.

I had a check of plugs, leads, cap etc...all seems ok. It runs fine with no sign of other problems.

 

I tried my wee ELM327 bluetooth thingy, but this is an earlier car which it wont connect to (I dont seem to have an engine management warning light either?) so I have no way of viewing data.

 

The Lambda sensor looks pretty crusty so I will try replacing that.....beyond that I dunno....will need to find a garage that can be bothered to look at it.

[Eddie Honda]

I dont know what the max limits are but I believe similar to UK.

Teneur en CO et valeur du lambda des gaz d'échappement :

9.1.1.1.1. Teneur en CO excessive ;

La teneur en CO au ralenti ne doit pas excéder 3,5 % pour les véhicules mis pour la première fois en circulation après le 1er octobre 1986. Elle ne doit pas excéder 4,5 % pour les véhicules mis pour la première fois en circulation entre le 1er octobre 1972 et le 30 septembre 1986. Les véhicules mis pour la première fois en circulation avant le 1er octobre 1972 sont dispensés de ce contrôle.

Pour les véhicules dont les émissions sont régulées par un système de dépollution comprenant un catalyseur, la teneur en CO ne peut excéder la valeur spécifiée par le constructeur lorsqu'elle existe ou à défaut les valeurs suivantes :

- 0,5 % au ralenti et 0,3 % au ralenti accéléré pour les véhicules immatriculés jusqu'au 1er juillet 2002 ;

- 0,3 % au ralenti et 0,2 % au ralenti accéléré pour les véhicules immatriculés ou mis en circulation après le 1er juillet 2002.

9.1.1.1.2. Valeur du lambda excessive ou insuffisante

A défaut de spécifications particulières mentionnées par le constructeur du véhicule, la valeur du lambda des gaz d'échappement ne doit pas être inférieure à 0,97 ni supérieure à 1,03, pour les voitures particulières mises pour la première fois en circulation à compter du 1er janvier 1994 et les véhicules autres que voitures particulières mis pour la première fois en circulation à compter du 1er janvier 1997, et dont les émissions sont régulées par un système de dépollution comprenant un catalyseur. Les autres véhicules ne sont pas soumis à ce contrôle.

Tout véhicule pour lequel une contre-visite a été prescrite au titre de la "teneur en CO et valeur du lambda des gaz d'échappement" fait l'objet, lors de la contre-visite, de l'ensemble des contrôles prévus :

- pour la "teneur en CO et valeur du lambda des gaz d'échappement" ;

- pour le dispositif de diagnostic embarqué (si concerné) ;

- pour le ou les points de la fonction 8 ayant rendu le contrôle impossible (le cas échéant).

 

https://www.legifrance.gouv.fr/affichTexte.do?cidTexte=LEGITEXT000020559004

https://fr.wikipedia.org/wiki/Contrôle_technique_des_véhicules_automobiles_en_France

[dieselnutjob]

I tried my wee ELM327 bluetooth thingy, but this is an earlier car which it wont connect to (I dont seem to have an engine management warning light either?) so I have no way of viewing data.

 

You need a pscan.  I sell them. See http://www.pscan.eu

[Junkman]

You can't do an emissions test by poking a probe into one of many tailpipes.

Makes me wonder with which degree of professional expertise the rest of the MoT test was conducted.

[dieselnutjob]

what is the correct way to measure emissions on a V engine which has two exhausts which are not connected?

[scaryoldcortina]

Test both banks, average the results.

[Craig the Princess]

I'm 3-0 on getting cars to pass emissions after failing first time by changing plugs and the air filter after an Italian tune up.

 

That two of the three (the two Vauxhalls oddly) have since been scraped is unrelated.

[Barry Cade]

You can't do an emissions test by poking a probe into one of many tailpipes.

Makes me wonder with which degree of professional expertise the rest of the MoT test was conducted.

You are just taking a sample though, not trying to catch the whole lot..? The gas is the same even if it comes down 100 pipes.