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E34 (1989 - 1995)

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  #1  
Old 03-26-2015, 06:26 AM
Mike5442 Mike5442 is offline
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Location: Connecticut
 
Join Date: Nov 2014
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Mein Auto: 1993 525i
Failed Emissions

I have just taken my car for the dreaded emissions test here in CT and have failed due to high Hydrocarbon output on the dyno at the 25mph test. My reading was 270 and the limit is 120.
The other specs were below the limit so I don't think my cat is the problem? Sounds like rich mixture maybe?
The car has no engine light and she runs just fine. I don't even know where to start
Any suggestions on what to look for on the E34?

Thank you!!
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  #2  
Old 03-26-2015, 09:10 AM
imae34driver imae34driver is offline
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Location: Orange County , CA
 
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Mein Auto: 1995 540i SPORT /6 spd
Change plugs,change oil, air up tires.. Drive it like you stole it and smog it got hot!
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  #3  
Old 03-26-2015, 10:15 AM
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TheEinstein TheEinstein is offline
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Mein Auto: E34 540i
^^+1^^ and I'd add, you may have a small vacuum leak. It may be worth cleaning the Mass Air Flow sensor while you're at it. You can use carb cleaner according to me, but I'd recommend sensor cleaner.
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1995 E34 540ia
160,000 Miles
VIN# ...GF32404
Hellrot Red

Fuelly

My Basic Repair History (Edited 1/27/2015)

Ongoing comparison between two E34 540ia's

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Last edited by TheEinstein; 03-26-2015 at 11:08 AM. Reason: Wording
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  #4  
Old 03-26-2015, 10:34 AM
Mike5442 Mike5442 is offline
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Location: Connecticut
 
Join Date: Nov 2014
Posts: 6
Mein Auto: 1993 525i
Quote:
Originally Posted by imae34driver View Post
Change plugs,change oil, air up tires.. Drive it like you stole it and smog it got hot!
Do you think changing the oil would really make a big difference in the hydrocarbon output?
I also just came off 30 miles on the highway so I was probably pretty hot too.
I thought I would be safe on plugs- I think I did them maybe 20,000miles ago. I guess that's a cheap way to start though.
The only trouble is I have no way to check if it makes a difference until I go for the re-test and potentially fail. : /
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  #5  
Old 03-26-2015, 11:19 AM
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TheEinstein TheEinstein is offline
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Mein Auto: E34 540i
How close to due is your oil change? If you're burning it... 20k on plugs is a fair amount, and a check of their condition would definitely be worth it. There's an additve made by CRC called something like "Guaranteed Emissions Pass." I think it's just a stabilizer/cleaner, but the point is to be sure your fuel system is clean. There are many things that can effect HC, engine operating temp comes into play quite heavily. What Imae suggested is easy, and in any case sounds like worth maintenance to be sure it is or isn't a simple fix.

Sorry to say, your catalytic converter isn't out of the woods yet either. Has it ever been changed? How old is it? Depending on the mileage on it, it could be long past it's life expectancy, and just not be efficient unless it's being pushed. How were the HC at idle numbers vs. allowed? And at ~50?
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1995 E34 540ia
160,000 Miles
VIN# ...GF32404
Hellrot Red

Fuelly

My Basic Repair History (Edited 1/27/2015)

Ongoing comparison between two E34 540ia's

OBC4 Hidden Functions : Link 1, Link 2
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  #6  
Old 03-26-2015, 11:19 AM
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TheEinstein TheEinstein is offline
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Location: Denver, CO
 
Join Date: Mar 2014
Posts: 900
Mein Auto: E34 540i
Duplicated above??? IDK
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1995 E34 540ia
160,000 Miles
VIN# ...GF32404
Hellrot Red

Fuelly

My Basic Repair History (Edited 1/27/2015)

Ongoing comparison between two E34 540ia's

OBC4 Hidden Functions : Link 1, Link 2

Last edited by TheEinstein; 03-26-2015 at 11:20 AM. Reason: The post appeared twice
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  #7  
Old 03-26-2015, 11:42 AM
Mike5442 Mike5442 is offline
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Location: Connecticut
 
Join Date: Nov 2014
Posts: 6
Mein Auto: 1993 525i
Quote:
Originally Posted by TheEinstein View Post
How close to due is your oil change? If you're burning it... 20k on plugs is a fair amount, and a check of their condition would definitely be worth it. There's an additve made by CRC called something like "Guaranteed Emissions Pass." I think it's just a stabilizer/cleaner, but the point is to be sure your fuel system is clean. There are many things that can effect HC, engine operating temp comes into play quite heavily. What Imae suggested is easy, and in any case sounds like worth maintenance to be sure it is or isn't a simple fix.

Sorry to say, your catalytic converter isn't out of the woods yet either. Has it ever been changed? How old is it? Depending on the mileage on it, it could be long past it's life expectancy, and just not be efficient unless it's being pushed. How were the HC at idle numbers vs. allowed? And at ~50?
I was considering pouring in some of that "Guaranteed to Pass", guess it couldn't hurt.
Hopefully it is just a simple fix. I will change the spark plugs and oil (I have another few thousand to go before I typically would but it can't hurt either).
The catalytic converter to my knowledge is the original 1993, and I am basically the second owner so it is highly likely.
But from what (I think) I understand is that the other readings, like the carbon monoxide, would also be high if it was the cat that was failing.

In Connecticut on a car this age they just do a reading at 25mph so I'm not sure to be honest. I just know the limit is 120 and mine read 270 on this test.
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  #8  
Old 03-27-2015, 06:05 PM
Larrick Larrick is offline
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Location: Berkeley California
 
Join Date: Sep 2009
Posts: 723
Mein Auto: 1994 525it
I have an interesting past thread on failing and then passing California smog
with a 1994 525i.
Believe it or not, an oil change will really help.
Like everyone has stated….bring it in HOT.

I went as far as to do a SeaFoam clean out through the intake.
There are a few You Tube videos, some with BMW's.

The crazy thing is that the numbers can be very different on smog tests only
a few minutes apart.
Always go to a station that will give a FREE second test.
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