cat converter fault code; decat or change or trial & error

[mrball]

Hi gurus, have a cat converter fault code on my 2006 e90 320i.
milege 130k.

symptoms:
1. sluggish response when accelerating out of turn; the throttle doesnt react well at 2000rpm and will pulse through to 4000rpm if throttled down.
2. engine dying suddenly on idling.
3. slight fluctuation of +/-50rpm on idling.

i have 3 solutions, wondering which is the best..

1. decat and pray hard that i dont get caught on the roads.(have to find a shop that can help with inspection later)
2. change cat coverter, thats if cat converter is indeed the fault. because i've read the forums and seems like many have problems with fuel pump and o2 sensors with such symptoms, even the workshop cant confirm for me that changing cat converter would solve the problem. (plus the cat is not cheap)
3. change out o2 sensors and fuel pumps for trial and error (since most forummers did those first).

input is much appreciated. thanks

 

[Red_Bean_Bun]

Re: cat converter fault code; decat or change or trial & error

Fuel pump and o2 sensors can be diagnosed for issues before changing it.

And if you disable the o2 sensors and its still having issues then look at the cats. And if its the cats - get a second hand one if you need to replace to cut cost.

Any smells ?

 

[mrball]

Re: cat converter fault code; decat or change or trial & error

thanks for the input!

fuel pump and o2 can be tested? i didnt know that. second hand is possible too since my car only has 3 years to go..

yes there's a slight burning smell.. does it mean anything?

 

[Mel279]

Re: cat converter fault code; decat or change or trial & error

how about your mass airflow sensor? sometimes loss power due to dirt on the sensor, clean it up before going for expensive repair. hope it helps

 

[Mockngbrd]

Re: cat converter fault code; decat or change or trial & error

did u pump at shell yio chu kang?

 

[lf37]

Re: cat converter fault code; decat or change or trial & error

Don't think it's worthwhile to get a genuine cat, try for replacement part?

 

[R2D]

Re: cat converter fault code; decat or change or trial & error

Only certain Cat converter faults results in poor response. This will include a cracked core or a blocked cat. (eg, choked with carbon from engine oil fouling)

What you are describing is usually due to other inherent problems with the engine.

Cat error usually refers to catalytic performance which just means that you are no longer a tree hugger and your car is producing more emissions that designed...

 

[mrball]

Re: cat converter fault code; decat or change or trial & error

Thanks for the input r2d.
I recently found out that the car is completely ok in sports mode, drives like a beast. But when in norml D mode, it feels like a pussy and faces a lack of steam at 2-3k rpm when on half throttle. If full throttle definitely no problem.

I met a few other guys with the same problem, the similarity is that we abuse the car like it was stolen. Lol. If r2d you possibly know whats wrong, could u kindly enlighten? Thank u

 

[sanerling]

Re: cat converter fault code; decat or change or trial & error

Only certain Cat converter faults results in poor response. This will include a cracked core or a blocked cat. (eg, choked with carbon from engine oil fouling)

What you are describing is usually due to other inherent problems with the engine.

Cat error usually refers to catalytic performance which just means that you are no longer a tree hugger and your car is producing more emissions that designed...

interesting. i read on bimmerpost that some of the e90 have this issue too. seems like n46 is not a good block.

 

[R2D]

Re: cat converter fault code; decat or change or trial & error

There are several possibilities, such as oil seperator, crankshaft sensor, DISA actuators and even some aftermarket filters. Of cos there are a few more causes but we would need to diagnose the car before making a more concrete answer.

Rod

 

[Jason8822]

Re: cat converter fault code; decat or change or trial & error

interesting. i read on bimmerpost that some of the e90 have this issue too. seems like n46 is not a good block.

If you say N46 is not a good block then may I know which bmw engine is good ?

 

[canuck78]

Re: cat converter fault code; decat or change or trial & error

3 years to go best to send to good workshop like r2d to get it looked into so you know exactly what's wrong

 

[rvt]

Re: cat converter fault code; decat or change or trial & error

Wah.... Sounds like appendicitis.
If inflamed/infected, just removed it....
If cat got problem, then decat?

I had the same problem.
So, I think... Likely sensor issues.... My opinion.