[MileCruncher]

I got the engine of my FIAT Uno 1.2 Petrol just overhauled as after 1.07 L Kms, it had started consuming oil in 2 cylinders. Even while it was consuming oil, the emissions as per PUC Certificate was way below the limit. But I got the PUC done yesterday and SPM and CO has increased considerably. I think my Catcon is working perfectly fine as if I hold my hand near the exhaust, I do get water vapour.

So what can be the reason for increase in emissions?

[SirAlec]

It may be many number of reasons. common is improper tuning.

Also how much has it run after the overhaul.

[MileCruncher]

Originally Posted by SirAlec

It may be many number of reasons. common is improper tuning.

Also how much has it run after the overhaul.

I don't think its improper tuning as its an SPFI with ECM and everything is stock and all sensors are perfectly working.

And after rebuild its done about 2k Kms.

[SS-Traveller]

Originally Posted by MileCruncher

...got the PUC done yesterday and SPM and CO has increased considerably.

Increased, but are they within permissible limits? Check your FE and spark plug colour to verify if the engine is running rich. Does the engine hunt/knock/choke when cold or when accelerated hard?

Too many reasons for an increase in emissions. Might be as simple as an ECM setting or faulty injector issue (or even a leaky exhaust before the overhaul), or it might be as bad as a poorly seated exhaust valve.

[MileCruncher]

Originally Posted by SS-Traveller

Increased, but are they within permissible limits? Check your FE and spark plug colour to verify if the engine is running rich. Does the engine hunt/knock/choke when cold or when accelerated hard?

Too many reasons for an increase in emissions. Might be as simple as an ECM setting or faulty injector issue (or even a leaky exhaust before the overhaul), or it might be as bad as a poorly seated exhaust valve.

Yes well within limits. The CO limit for 2000 Make petrol cars is 3.00% and mine is giving 2.16%. Previously it used to hover around 0.5-0.6% . (Need to see the exact figures for SPM)

I'm getting a FE of about 11KMPL which is slightly better than before and the Spark Plugs are biscuit colour. No engine hunting/knocking or chocking, Has become much more free revving than before. While overhauling, the valve seating has been lapped and something minor done to the head also to improve slight performance.

[vigsom]

Originally Posted by MileCruncher

Spark Plugs are biscuit colour. No engine hunting/knocking or chocking, .

that's healthy - It could be just that you need some fine tuning

[SS-Traveller]

Originally Posted by MileCruncher

Yes well within limits. ...mine is giving 2.16%.
...FE of about 11KMPL which is slightly better than before and the Spark Plugs are biscuit colour. No engine hunting/knocking or chocking, Has become much more free revving than before. While overhauling, the valve seating has been lapped and something minor done to the head also to improve slight performance.

Forget about the issue and go to sleep! Check PUC again after 3 months, keep an eye on the FE, and the next time ensure that you've completed a long high speed drive before checking. And switch off that AC at least 15 minutes before checking.

A fuel-efficient car is not usually a polluting car.

Happy driving!