missfire and bad smell - urgent

[doely_gti]

well i started the 172 last night and it seems to be running on 3 cyl's (was fine 10 mins before)

also there is the WORST eggy smell EVER coming from the exhaust which i was always told - egg = cat gone

but can the cat being buggered make it run like a bag of spanners?


thanks in advance for any help

 

[allyrs]

have you smelt the egg smell before or was this the first time? usually the smell will get progressively worse with a clogging cat. Over fueling can cause the egg smell too. so a sensor could be to blame.

if you can get the car to kwikfit they can see if there are hot or cold spots on the cat with an infrared heat gun. they should do it for free. then you get to know if its on its way out.

check your plugs for coking and leads.

i very much doubt the cat is to blame for the non starting. more likely an ingnition/sensor/fueling prob.

though if the cat had collapsed excessive backpressure can F the engine, though this is very rare and you would have noticed power loss for several miles and prob a burning smell lol

 

[SBV116]

The smell is due to the unburnt fuel being launched down your exhaust!! Usually the coil pack!

 

[doely_gti]

darn, will have to get the coilpack off tomorrow.

has been perfect until now, no smell etc

ah well cheers guys, mucho grasias