Technical I need help with emissions

[AndyHill27]

I have a fiat punto mk2 2004 and it had a really bad emissions issue i have no idea what else it could be its high on everything for the test and ive had new catalytic converter new lamb sensors and im just stumped on what to do ive asked everyone i know but befor i did the cat they all said it would be that so i changed it and barely any change on emissions test i really need help

 

[bugsymike]

I have a fiat punto mk2 2004 and it had a really bad emissions issue i have no idea what else it could be its high on everything for the test and ive had new catalytic converter new lamb sensors and im just stumped on what to do ive asked everyone i know but befor i did the cat they all said it would be that so i changed it and barely any change on emissions test i really need help

Can you read the error codes?
Also more details on engine type, size, etc.

 

[AndyHill27]

It is a 1.2 8v 188A400 there are no engine code that i can see with my scanner and nothing on the dash but ive changed everything from spark plugs to injectors and i have no idea what it could be

 

[AndyRKett]

If it’s high on CO (carbon monoxide) you have an issue with the cat still, the whole point in a cat is to turn CO into CO2 through oxidisation and to turn nitrogen-oxides into nitrogen and oxygen through reduction.

If you are still having high CO and high NOX then you have an issue with the cat especially on a petrol car

If you’ve changed everything else and the engine is running well, the o2 sensor works and there are no warning lights on the dash then the problem I still the CAT.

Did you buy a brand new cat from a reputable company or did you get it cheap from somewhere like eBay?

 

[GrandePunto PL]

Show the results from gas analyzer.
What's the oil consumption? Maybe it's burning oil.
Or it's a ECU failure.
Or new "cat" and sensors are chap replacement, or straight fakes.

 

[AndyHill27]

If it’s high on CO (carbon monoxide) you have an issue with the cat still, the whole point in a cat is to turn CO into CO2 through oxidisation and to turn nitrogen-oxides into nitrogen and oxygen through reduction.

If you are still having high CO and high NOX then you have an issue with the cat especially on a petrol car

If you’ve changed everything else and the engine is running well, the o2 sensor works and there are no warning lights on the dash then the problem I still the CAT.

Did you buy a brand new cat from a reputable company or did you get it cheap from somewhere like eBay?

I got a new cat

 

[AndyHill27]

Show the results from gas analyzer.
What's the oil consumption? Maybe it's burning oil.
Or it's a ECU failure.
Or new "cat" and sensors are chap replacement, or straight fakes.

Have already replaced the cat and i had new sensors befor i change the cat

 

[GrandePunto PL]

Answer the questions. We know you have NEW cat. So what.
Is it original or cheap-ass fake?

Besides that, basics (how ECU controls the engine) are: MAP, temperature, ignition system, exhaust leaks, valve clearance (all 8V FIRE units)...

 

[AndyRKett]

I got a new cat

Go back and read what has been said, just because you have replaced it, that doesn’t mean it is not still the problem.

Exhaust gases and the catalytic converter is all basic chemistry, and if you are getting certain gases out of the tail pipe then the cat isn’t working

 

[AndyHill27]

Answer the questions. We know you have NEW cat. So what.
Is it original or cheap-ass fake?

Its from a-z motors brand new

 

[GrandePunto PL]

Cat is not a magic furnace, which burns any junk. The exhaust gases must be fairly clean initially, plus lambda around 1,00 already (0,97-1,03-ish for example).
In extreme cases you can kill the new one if you flood it with fuel/oil/coolant.

First attempt to fix the car was a bit improper. I mean: is (was) the cat just old and faulty (naturally) or something killed it? And now you will repeat the cycle.

Now you (or your mechanic) must do "A-Z" maintenance, go through the full check list. Maintenance tasks/items. Measurements. Adjustments. Diagnostics (OBD2 + oscilloscope + gas analyzer during those checks). "Parts cannon" method failed.

 

[AndyRKett]

Cat is not a magic furnace, which burns any junk. The exhaust gases must be fairly clean initially, plus lambda around 1,00 already (0,97-1,03 for example).

No it’s not a furnace nor does it “burn” anything.

Now you (or your mechanic) must do "A-Z" maintenance, go through the full check list. Maintenance tasks/items. Measurements. Adjustments. Diagnostics (OBD2 + oscilloscope + gas analyzer during those checks). "Parts cannon" method failed.

As usual super helpful

I would just add if you feel the need to pull out an oscilloscope when doing car maintenance, you’ve gone way to far and probably need to go take a lay down in a dark room to calm down.

Its from a-z motors brand new

First up has it been serviced, has it had a new air filter recently, any leaks in the intake or exhaust system.
Get a can of carb cleaner for about £5 and clean up the throttle body and any intake pipes.

There is usually a crank case breather that vents into the air intake system and it this is pushing out a lot of oil vapour then it can clog up the intake side of things and fowl the throttle body.

Take the plugs out make sure they are gaped correctly that the HT leads are in a good condition and correctly fitted to the coils.

look up on YouTube how to test your O2 sensor, you will need a multimeter, and you can get one on Amazon like this for less than a tenner which will do everything you need it to do https://amzn.to/3PZW6qQ

This will tell you if the O2 sensor is working properly and if not then the engine could be putting in more fuel than is needed leading to incomplete combustion, higher CO higher hydrocarbons.

If it is only marginally outside of spec, then it may need an “Italian tune up” especially if the car used to belong to someone who only ever drove it to the bingo once a month at 20 mph. “An Italian tune up” is code for take it down your nearest bypass screaming the nuts out of the engine in 3rd or 4th gear and not changing up, taking down some country lanes in a “spirited fashion” basically thrash the hell out of it for a few miles, no car likes to be left standing and they like to be driven hard especially these little 1,2 engines they love to be rev’d
In Italy if the car isn’t constantly bouncing off the Rev limiter you’re not driving it properly.

If you are 100% confident you’ve not got a dodgy CAT then these are the things i’d be doing.

If you have a gas analyser then you probably wouldn’t be here and if you have an oscilloscope that that’s a clear signal you have no friends.

 

[GrandePunto PL]

Most folks think that way about "cats": it just cleans exhaust, mate - nope.

If you are professional mechanic and don't have a gas analyzer and scope in your shop, you are f-ing clown. Most are (part swapers).
Rant wasn't about amateurs/hobbyists.

Let's throw another batch of random new parts and see if it helps. And meanwhile spray some brake cleaner into throttle. Now, THAT's helpful.

 

[AndyRKett]

Most folks think that way about "cats": it just cleans exhaust, mate - nope.

I’m begining to suspect you don’t know anything about how a CAT works…..

No mechanics shops have oscilloscopes in them, what mechanic has the time to sit around fiddling about with a scope, which is not going to tell them anything that the car couldn’t tell them itself via the OBD port.

Also you know carb cleaner and brake cleaner have a different composition, you don’t spray brake cleaner on intake parts where as carb cleaner is literally made for that exact job

 

[bugsymike]

I’m begining to suspect you don’t know anything about how a CAT works…..

No mechanics shops have oscilloscopes in them, what mechanic has the time to sit around fiddling about with a scope, which is not going to tell them anything that the car couldn’t tell them itself via the OBD port.

Also you know carb cleaner and brake cleaner have a different composition, you don’t spray brake cleaner on intake parts where as carb cleaner is literally made for that exact job

In 55 years working in the Motortrade for Dealers and later in my own business I have only needed to use one Oscilloscope, that was on a Crypton Tuner in the 1970s where I used it to show how much higher kilovolts were needed to fire resister spark plugs than non resister and that it was the reason HT leads and coils etc. shorted out more in damp weather than in the past. Apart from that we managed with strobe timing lights , volt and amp meters and maybe a dwell meter which would confirm what we had already set the contact points to using feeler gauges.
I accept that modern vehicles are much more specialsed with sensors and ECUs needing high tech equipment to locate certain faults, but in most cases the garages would send the vehicle to a specialist as it was a more economical use of the engineers time.
"Horses for courses " as they used to say. When I did my apprenticeship the mechanic was expected to strip and rebuild engines,gearboxes,axles, suspension, brakes to a high standard and have a good understanding of the charging systems and wiring, whereas now everything is farmed out to a "specialist" as more cost efficient.
A good Specialist would efficient locate the electrical issue in a modern vehicle much quicker than I could, but I very much doubt if he could do all the things I was trained to do either.

 

[AndyRKett]

I think you highlight the point that by the time you are shipping these things out to specialists and the hourly rate that a specialist would charge, you can buy and try a lot of sensors before you out spend the cost of any specialist

Scanning the OBD port will soon tell you if a sensor is not outputting the correct readings a simple multimeter will tell you if there is a wiring problem.

In this case it’s a fairly simple high emissions issue which there are dozens of things to try before reaching for an oscilloscope, and given the value of these cars now I’d say scrapping it and buying another car, given the price of a specialist.


Italian tune up and a can of carb cleaner (not brake cleaner) may well be all it needs