old school pete

my99 classic uk turbo failed the mot this week on emissions

not really sure what it all the following means and am after some advice before randomly throwing money at things!!

fast idle
co 3.93
hc 197
lambda 0.88

second fast idle
co 4.16
hc 165
lambda 0.87

added this wrongly to an existing thread last night cos stupidly couldnt find how to create a new one, sorry about that

dont know what to start changing (should I start with lambda sensor?), any advice very welcome

thanks

pete

stef_2010

iTrader: (3)

Dont know if Subaru engines would be fine with this but my mechanic stuck loads of engine cleaner/redex in the tank to get my fiesta past the MOT.............

Hadez

Has you car been modified/decatted?

I know without cats at a normal testing station my Scooby would fail miserably. You normally need a friendly mot station/mechanic that will put the cats on for the test.

winker

iTrader: (1)

Thats not to bad its your co thats to high lamba is ok and hc is in limit my mot was fine with a decat did you get the car really warmed up before u went for test?

classicgc8

iTrader: (4)

co level need to 0.30% max,hc limit is only just in,200 ppm is max and lambda is showing massively rich values have to be between 0.97 and 1.03, should be 1.00- (air/fuel ratio of 14.75 to 1 stochiometric)
suggest lambda sensor issue however due to the high hydrocarbon level it may be due to misfire,does the car drive normally

old school pete

thanks for the replies

car is running higher boost and fuel than standard but still has cat

been standing for a while but just had new sparg plugs, fuel filter and oil change

put some fuel addative in and topped it up with super and took at for a good drive on way to test station

the car drives very well - no missing and only a bit lumpy on tick over

Splitpin

Yes, you should start with the lambda sensor. Those two tests indicate that it is running very rich - those figures indicate it is running between 12.7 and 12.93:1 under closed loop. Likiest cause of that is the sensor being degraded beyond the point of usefulness, although it may also be that the catalyst(s) is/are also degraded.

How many cats does it have? As standard it should have two. Have you removed one of them or does it still have both?

What fuel additive did you put in, and was there a reason for doing this? Under normal circumstances this should be unnecessary and depending on what you used, may be counterproductive. If the car has been standing long enough for the fuel to go off, the best option is simply to drain it out of the tank and replace with fresh.

Some care is needed there. While it might be nothing at all, a consequence of the fuel currently in the tank, or simply be a result of overfuelling secondary to a failed lambda sensor, "a bit lumpy on tick over" might be a symptom of the early stages of MAF sensor failure.

Would suggest that you replace the lambda sensor, reset the ECU, ensure the engine is running on unadulterated Super Unleaded/V-Power/Tesco Steroids/etc and then see if this behaviour at idle has improved. If this "lumpiness" is still evident, if you search my posting history you will find some advice that will help you decide whether or not to replace the airflow meter.

Suffice to say for the time being that if you have seen anything elsewhere about a test that involves unplugging the meter with the engine running and seeing whether or not it stalls, that "test" is bull**** and proves nothing - do not attempt it!

Jukesy007

Mine failed on the emissions this year in January and as a result had to have both lambda sensors replaced.

Was pretty expensive but as i got snowed in i couldnt get the MOT done till the very last day and was therefore tied to having to get it done at that particula garage as could not risk driving it without an MOT for the obvious reasons.

But since ive had it done it hasnt once been lumpy on start and has been as good as gold.