failed smog, high HC at idle (pic)

[AMDdude]

Anyone know what might cause high HC at idle only? Limit is 200, I got 291. I have a check engine light, its probably one of the O2 sensors but my CO % passed, although quite close too. Any way to be sure before I spend money on O2 sensor?

Thanks.

[neptronix]

First off, you need to find out what that engine code is before you do anything.
There are way too many things that could cause this.

second off, your car seems to be idling high.. 700rpm? that's not right. Either they didn't warm the car up enough, it was 0 degrees outside, or something is wrong with your car.
My US 328is idles at 500rpm for reference.

[terrysumner]

I agree with neptronix...you NEED to know what that code is before proceeding. Diagnose..don't guess. High HC means it's running rich. Could be misfiring, could be bad O2 sensors or a bunch of other things. Find out the code and post that here...
If there's an Autozone near you stop in and have the code read.
Terry

[strad]

Vacuum leaks can cause high HC. It's called a lean misfire. But it is foolish to proceed without knowing what the codes are.

[neptronix]

High HC does not necessarily mean it's running rich. When catalytic convertors are WAY overdue for a change, these numbers do go out the roof, especially hydrocarbons.
Look at his CO%.. he could have failed on that number also if the stars weren't aligned right

I've got $5 on bad catalytic convertors but it could be a lot of things.

I just replaced mine with some magnaflow cats and my car went from a 'smoke stack on wheels' to 'new off the lot' instantly. Just to provide an example.

[magnaflowrep]

High HC does not necessarily mean it's running rich. When catalytic convertors are WAY overdue for a change, these numbers do go out the roof, especially hydrocarbons.
Look at his CO%.. he could have failed on that number also if the stars weren't aligned right

I've got $5 on bad catalytic convertors but it could be a lot of things.

I just replaced mine with some magnaflow cats and my car went from a 'smoke stack on wheels' to 'new off the lot' instantly. Just to provide an example.

This is a very good exsplanation. what people have to understand about cats is that just because you have a PO420 or PO430 code it does not mean you have a faulty converter. what it states is that there is something that is making the emmission system not work properly giving you a rich or lean condition. If you check the shell of the cat a lot of times it will give you an idea of what the under lying issue is. if the shell is a blue or purplish color than you are running in a rich issue if you have a bronze color to the converter than you have a lean issue. if you have any questions on converters please let me know i would love to help.

[kevinqjhps]

This is a very good exsplanation. what people have to understand about cats is that just because you have a PO420 or PO430 code it does not mean you have a faulty converter. what it states is that there is something that is making the emmission system not work properly giving you a rich or lean condition. If you check the shell of the cat a lot of times it will give you an idea of what the under lying issue is. if the shell is a blue or purplish color than you are running in a rich issue if you have a bronze color to the converter than you have a lean issue. if you have any questions on converters please let me know i would love to help.

BINGO!!!!!!!!!!!!!!!! Treat the cause, NOT the symptoms.

[AMDdude]

They scanned it, said B2S1 O2 sensor (heated circuit failed). So that's the Bank2 pre-cat sensor. I've already ordered 2 NGK sensors from pelicanparts, hopefully that fixes the problem.

[neptronix]

sounds like good news.. so far

[fPortal]

I just had the same thing happen to me, will Autozone scan this for free?

[Blanco]

I just had the same thing happen to me, will Autozone scan this for free?

You have an OBDI car so you can check the codes yourself.
http://www.pelicanparts.com/BMW/tech...de_Reading.htm

[fPortal]

That link is very appreciated. Thank you.
I am not really wanting to shell out the extremely overpriced amount for the cat on this car.

[tk7294]

Just a helpful tip that you may already know. Next time you get your emissions test done make sure that the engine temp is at the highest it can be ie: take your car on some freeway runs b4 you get the test done. I made the mistake of getting the test done cold, it didnt pass and the emissions guy told me what to do. Second time passed with no problems...

[Blanco]

That link is very appreciated. Thank you.
I am not really wanting to shell out the extremely overpriced amount for the cat on this car.

You're very welcome. You can get Magnaflow cats for around half the price of OE replacements. Should cost around $200 at a small custom exhaust shop.

Just a helpful tip that you may already know. Next time you get your emissions test done make sure that the engine temp is at the highest it can be ie: take your car on some freeway runs b4 you get the test done. I made the mistake of getting the test done cold, it didnt pass and the emissions guy told me what to do. Second time passed with no problems...

Very true. I just got my car smog'd a few hours ago and I took it on the highway for about 20 minutes at 70-80mph. I passed everything with super low numbers except HC at idle which was 48/100 with an average of 12. My air filter's dirty though, so that's likely the issue.

[fPortal]

You seem to know the code thing pretty well, may I ask a question?

After running the OBD1 scan thing, I think I am doing it right, I keep getting 1215 then about a 2.5 second of the light being on, then the 1215 repeats, and keeps this up. Does this just mean I need a new MAF?

[Blanco]

Thank you, but I'm still pretty new to BMWs myself.

You probably just need to clean your MAF. There's a DIY on the forum. Make sure you don't use carb/brake cleaner, only use MAF cleaner.

[fPortal]

Thanks for the reply.
I followed that DIY about a week ago. The strange part is that the code for the MAF says
"A big hole in one of your fuel injection intake boots may cause the car to stall and generate this code."
Does not seem to state anything about the MAF.

[Blanco]

Have you checked the intake elbow for cracks? That seems to be a common problem.

[fPortal]

Yea, that was my next move. the two hoses that are attached to the bottom of that part are kinda cracked where they connect to the bend. Do you know what those go to?

[Blanco]

No I don't. I know that the larger of the two on my car is split down both seams. I taped it up and used a hose clamp until I find out, because the opposite end appears to be a larger diameter.

[fPortal]

Yea, that is kinda what I am doing right now as well.

[Blanco]

It worked well enough that I passed smog.

My readings were:

Idle: 729rpm | 15.3% CO2 | 0.0 O2 | 43/100 HC | 0.08/1.0 CO%
2500rpm: 2600rpm | 15.3% CO2 | 0.0 O2 | 12/100 HC | 0.01/1.0 CO%

[fPortal]

My idle was way out, the 2500 rpm part passed. Idle HC was 323/100 or something like that.