hi my girlfriends bravo 1.616v failed its mot today on emmisions! my thoughts are with the lambda sensor! what do you guys think?


first fast idle test min max
co level @2746 rpm = 10.09% fail 0.30
hc level @2746 rpm = 432ppm fail 200
lambda @2746 rpm = 0.73 fail 0.97 1.03


second fast idle test
co level @2627 rpm = 11.33% fail 0.30
hc level @2627 rpm = 705ppm fail 200
lambda @2627 rpm = 0.69 fail 0.97 1.03


natural idle test
co level @ 798rpm = 9.55% fail 0.35

plese help a desperate fiat owner who is havin to run his wife around!

Lambda is very low meaning the car is running very rich.

Either the coolant temp sensor is reporting a wrong temperature, the air filter is blocked, or probably the lambda is faulty.

Those values are very high.

I just had an emmissions test on my decat car, it failed, but only on CO at 2.5%.

Rich running will massively increase the HC and CO as shown.

Cheers,

Kristian

Go and have an injectors cleaning. Before couple of years i had a similar problem with my brava and all the mechanics was telling me the fault is the lamda, the fault is the catalyst, but one told me i will clean your injectors and all will be fine, and yes CO and HC went down. If you do a diagnostic check it will not show you any fault code!

BRAVARulez said:

Go and have an injectors cleaning. Before couple of years i had a similar problem with my brava and all the mechanics was telling me the fault is the lamda, the fault is the catalyst, but one told me i will clean your injectors and all will be fine, and yes CO and HC went down. If you do a diagnostic check it will not show you any fault code!

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yup, it's always best to take your car out for a good run before the MoT especially if it's only taken on short trips. run it at higher revs eg. higher end of 3rd/4th on motorway for just a short time. especially good with diesels you'll get a big black cloud of soot sometimes.

if the 1.6 is anything like my 1.4 tipo (related to the 1.6 but a lot different heads) it runs poorly unless i take it out every now and then for a good run. though that could just be me thinking that.

Basic fault finding for advanced emission test failures:

1. If a vehicle fails for high CO at idle and /or fast idle then.... if Lambda is too low, the mixture is too rich. This can be caused either by a misfire or by a faulty Lambda sensor. If it's running very rich, the 02 and HC will be higher than normal.
2. if it has a high Lambda and high 02 (0.5 to 1.5%), the "CAT" could be faulty. Before condemning it make sure its hot enough to work, the Lambda and other sensors are working OK and the exhaust downpipe hasn't got any leaks.
3. if the vehicle fails for high HC then ...if the CO passes, the vehicle is probably misfiring. Or if the CO fails and the Lambda reading is too low, the mixture is probably too rich and it may also be misfiring.
4. if the CO fails, the Lambda reading is high and the O2 reading is high (0.5 to 1.5%) the "CAT" could be faulty. Again check out the simple measures above before condemning it.
5. if the Lambda fails then...if its too high the Lambda sensor may be faulty, the mixture may be too weak or there may be a hole in the exhaust downpipe. If Lambda is too low the sensor may be faulty, the mixture may be rich or the vehicle may be misfiring.

good news is you can rule out CAT, lambda sensor and exhaust leak.

it is running very rich. on the 1.6 16v that is usually due to the injectors. check the resistance of them all, cleaning wont help with the very common 1.6 fault of failing injectors. do a search and you'll find hundreds of threads on the subject.

put a new lambda in some optimax fuel and a good thrash down the duel carrigeway and she passed today with really low emissions!