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[Enceladus]

How did the mechanic fix it? Looks like he cut the pre-cat out with an acetylene torch. But did he weld in a new pre-cat or just weld in a piece of pipe to bridge the gap? Or did he install a new down-pipe and cat from the manifold?

AIUI the pre-cat is part of the Euro 4 emissions compliance. Most Omegas are Euro 3, however 2.2 16V MY2003s are Euro 4. Not entirely sure how it works but the intent is to light-up the main cat(s) faster. Presumably by the pre-cat heating up quickly (due to proximity to the exhaust manifold) and burning off excess hydrocarbons in the rich(er) cold start mixture, such that the downstream exhaust gas is hotter.

Certainly my 2003 2.2 heats up significantly quicker than the 2.5 V6 with (working) secondary air injection into the exhaust manifolds.

For the purposes of any official testing my guess is that it won't matter if the pre-cat is missing so long as the engine and exhaust is warmed up before the test. Not sure about the UK however?

Anyway glad to hear it's working.

[TheBoy]

If the cat failed on a 2.2, I suspect that is a symptom, not the cause.

Get the live data readings.


And personally, I think your mechanic is inept, sorry.

[abokayed]

Crap fuel probably killed it and once blocked, it quickly builds back pressure leading to all  the other issues...

Yes That could be a good reason , i also cleaned the fuel injectors Yesterday to make sure the system is clean and put some fuel cleaner inside my tank

[abokayed]

How did the mechanic fix it? Looks like he cut the pre-cat out with an acetylene torch. But did he weld in a new pre-cat or just weld in a piece of pipe to bridge the gap? Or did he install a new down-pipe and cat from the manifold?

AIUI the pre-cat is part of the Euro 4 emissions compliance. Most Omegas are Euro 3, however 2.2 16V MY2003s are Euro 4. Not entirely sure how it works but the intent is to light-up the main cat(s) faster. Presumably by the pre-cat heating up quickly (due to proximity to the exhaust manifold) and burning off excess hydrocarbons in the rich(er) cold start mixture, such that the downstream exhaust gas is hotter.

Certainly my 2003 2.2 heats up significantly quicker than the 2.5 V6 with (working) secondary air injection into the exhaust manifolds.

For the purposes of any official testing my guess is that it won't matter if the pre-cat is missing so long as the engine and exhaust is warmed up before the test. Not sure about the UK however?

Anyway glad to hear it's working.

Thank you for the valuable information  , what he did is cut that cat and replace it with a straight pipe , im not sure its really a Catalytic Converter , because it doesnt seem to have any kind of stages or anything similar to a real CAT it is just a piece of pipe that have some round metal rings that have small holes in them , i think the previous owner took it to some cheap exhaust shop to replace some parts and this is what they came with

[abokayed]

If the cat failed on a 2.2, I suspect that is a symptom, not the cause.

Get the live data readings.


And personally, I think your mechanic is inept, sorry.

i may agree with you that it is a symptom , but in the first place that wasn't even a Cat , it doesnt seem to be one , it is just a round looking pipe with metal rings inside it with holes in them , and they were broken and making a ringing noise , i think the previous owner took it to some cheap exhaust shop with uneducated staff that replaced the wrong parts in wrong places.

about the live readings what kind of data is needed to tell about my issue , can you please guide me to them

Thanks!

[TheBoy]

Start with the LTFT.

[abokayed]

Start with the LTFT.

i watched some youtube videos to understand the long term and short term fuel trims , so now i can do this diagnosis my self i have my own Bluedriver OBD , ill go test them and see what i come out with , noting that the car now is working perfectly and strong

Thanks for your Guideline!