2004 BMW 325CI Catalytic Converter problems

[Jeanne228]

Hi,

I have 157K on my car and I was told last night by BMW dealership I need new converters at $3800 and don’t have the cash to fix. They tested exhaust back pressure and concluded. I spent 1200 new mechanic last month who failed to read numbers properly and told me converters were fine. No check engine light and no codes displayed.

Car sluggish little power when accelerating shifting. This is my only car and asking about using lacquer thinner in gas tank to clean and hopefully help. If not, removing converters and having them cleaned and reinstalled. Does this make sense ? Has anyone tried this ? I would be grateful for any help.

Thank you

[Ctwide3project]

I would personally highly advise against lacquer thinner in the tank. Removing cats to clean them just seems implausible to me, I've been working on cars for about 25 years and knowing how cats work and the molecular make up of them, I just dont see that happening. At best if you can remove the build up in the hundreds of TINY passageways, chances are you will destroy the catalyst material and create a check engine light with potential driveability issues. Just my opinion

Sent from my SM-G960U using Tapatalk

[All2kool]

I would personally highly advise against lacquer thinner in the tank.

I did this on my 1996 Lincoln Town Car and although it didn't fix the issue I was having (fouled &rusted plug wire discovered later), it didn't hurt anything either.

[nonturbodan]

Clogged cats with no check engine light for catalyst efficiency would seem odd to me. What were the back pressure readings?

[jclausen]

The only m54 cats Ive had to replace was because the weld along the flange to head area was leaking causing an oxygen sensor problem you can al so reed inlet and out let temps to check condition of cats funny there is no check engine light

[Jeanne2004]

Hi, sorry for months later response - was unable to get on the site. I don't know what the readings were on the car but dealer claims I need them. This has been going on for several months and have been forced to rent cars off and on, etc. I drive car sometimes when necessary and have to floor it when shifting in all gears so it doesn't jerk. One code on car only - P0411 secondary air injection system incorrect flow detected. The pump was checked and is fine and was told a hose type item that attaches to it should be replaced $300. I can't imagine this being the culprit of low power. I wish I knew a qualified mechanic somewhere in NY to tow to.

[Jeanne2004]

Hi, sorry for such lengthy time before responding - unable to access site. I have P0411 secondary air injection code - that is only one on car. Pump was checked and find. Was told a hose type short item that attaches to it needs to be replaced but this certainly wouldn't cause the horror with no power and when shifting, I have to floor it in all gears to prevent the car from jerking. Straight roads it runs great

[Muzz258]

Hi Jeanne

The usual backyard test for blocked Cats, is to remove the pre-cat O2 (Lamba) sensors and go for a quick drive. If the performance of the car is improved, then you have blocked cats.

I see that you normally go to the mechanic to get things repaired, so that indicates that you are not very car DIY handy. Suggest you go to your local mechanic and get him/her to do the above test. If you need new Cats, it either buy new or go to the junk yard and see if you can find some second-hand ones. They will be cheaper but not as cost effective as you just don't know how many miles of use they still have in them.

[easymoney]

Hi Jeanne

The usual backyard test for blocked Cats, is to remove the pre-cat O2 (Lamba) sensors and go for a quick drive. If the performance of the car is improved, then you have blocked cats.

I see that you normally go to the mechanic to get things repaired, so that indicates that you are not very car DIY handy. Suggest you go to your local mechanic and get him/her to do the above test. If you need new Cats, it either buy new or go to the junk yard and see if you can find some second-hand ones. They will be cheaper but not as cost effective as you just don't know how many miles of use they still have in them.

It is against the law for junkyards to sell catalyctic converters unless they know you personally. You best bet is to source one out from a private party, CL or Egay.

[Muzz258]

It is against the law for junkyards to sell catalyctic converters unless they know you personally. You best bet is to source one out from a private party, CL or Egay.

Thank you for that. I don't know the laws in the USA on selling second-hand cats.

[nonturbodan]

Yeah, they want you to buy a brand new one rather than a perfectly good used one. Ebay won't let you list them used, but in the case of the M54 its built into the manifold, so if you list them as used manifolds they don't know the difference.

[Mason328i]

Hello Jeanne2004,

Your engine might need a tune-up: new spark plugs, new coil packs, and might also be time for the engine oil & filter change. Might also need a new air filter.
Do to the high mileage, I'll bet that a tune-up is long overdue !
Worn out spark plugs will prevent the engine from developing power, and "driveability" will be terrible.

I believe that those mechanics that can't seem to give you good advice are just trying to create an expensive repair at your expense !

You did say that the engine creates good power and acceleration , when you are driving on a straight road.

There is also the possibility that your car needs new converters.

Very expensive.

Definitely do the tune-up & oil change first, then take your car for a test drive.

Let me know if this helps, or not.

[jclausen]

You need to find a better shop

[nonturbodan]

Hello Jeanne2004,

Your engine might need a tune-up: new spark plugs, new coil packs, and might also be time for the engine oil & filter change. Might also need a new air filter.
Do to the high mileage, I'll bet that a tune-up is long overdue !
Worn out spark plugs will prevent the engine from developing power, and "driveability" will be terrible.

I believe that those mechanics that can't seem to give you good advice are just trying to create an expensive repair at your expense !

You did say that the engine creates good power and acceleration , when you are driving on a straight road.

There is also the possibility that your car needs new converters.

Very expensive.

Definitely do the tune-up & oil change first, then take your car for a test drive.

Let me know if this helps, or not.

No misfire codes, I'm sure the coils are fine. The plugs may be overdue but not to the extent of causing problems. Not without misfiring and cylinder deactivation.