misfiring engine

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  #1  
Old 12-17-03, 06:02 PM
jda
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Unhappy misfiring engine

Two weeks ago my husband changed the oil in our 1997 BMW 540i. It was cold that day and apparently he did not get all the old oil out. When we drove it the next day, we drove about 40 miles before it started misfiring. The check engine light came on. We were about 20 miles from home but we made it. He called the mechanic and he (the mechanic) thought it could be the plugs. when my husband changed them he noticed oil on the back four. After telling the mechanic this, it was recommended that we have the car towed to his shop. After hooking up to the computer, he found out that there was way too much oil in the car. He let it drain all night, replaced the filter, put in new oil and cleaned the engine. When we got it back it ran great. After a day or so we noticed smoke from the exhaust when it is first turned on. The mechanic said this would happen for a week or so until all the oil gets out. We have had the car back from him for four days. Today the check engine light came back on. I took it to the same guy and he found it about a quart low. He said he was conservative when he put oil in it because he knew the engine had taken in a lot of the oil my husband put in. He reset the light and put a quart in. A couple of hours later, light on again and the engine is misfiring badly! HELP! What could be causing this?
 
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  #2  
Old 12-17-03, 06:15 PM
darrell McCoy
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Hmmm. Time for another mech. I dont see how you could not have gotten all the oil out. Maybe you put in more than book recommended. Only one instance I can remember many years ago, a fellow drained tranny and put an extra 5 qts of oil in his engine. What's with the "He cleaned engine part"??? How many miles are on this engine?
 
  #3  
Old 12-17-03, 06:18 PM
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He has probably damaged the catalytic converter. If it is stopped up it will put trememndous strain on the engine. Have the mechanic do a back pressure test to verify this.
Hope this helps,
Billy
 
  #4  
Old 12-17-03, 07:21 PM
jda
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There are 86000 miles on the engine. We will have the back pressure test performed. Is it safe to drive to the mechanic or should we have it towed?
 
  #5  
Old 12-17-03, 07:24 PM
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Depends on the distance. Not really safe, but you can take your chances.
Billy
 
  #6  
Old 12-17-03, 07:26 PM
jda
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If the catalytic converter is stopped up, does it have to be replaced? Can it be cleaned? How could too much oil damage it?
 
  #7  
Old 12-17-03, 07:33 PM
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Yes it has to be replaced. Never heard of one being cleaned.
Billy


I just noticed that you're in Chapel Hill. Can I inquire who you took your car too? I know alot of the guys there as I used to work at the Chrysler Dealership before it closed in January.
 
  #8  
Old 12-17-03, 07:36 PM
jda
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I was afraid you were going to say that.
We took it to a business in Durham, a place recommended to us
This is a nightmare. I can't believe changing the oil would cause problems like this.
How much are the converters anyway?
 

Last edited by jda; 12-19-03 at 03:36 AM.
  #9  
Old 12-17-03, 07:42 PM
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I wouldnt go off the deep end just yet. Be sure that that is in fact the problem. It is best to rule out a problem than to just replace and find out you spent money you didnt have to.
Billy

I havent heard of that shop I dont think.
 
  #10  
Old 12-17-03, 07:47 PM
jda
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Thanks for the info. My husband is rolling his eyes at me because I am a little freaked out. Mr. M. is a one man operation. He came recommended by someone else. He primarily works on VW's BMW's, Porsche's etc. Is the back pressure test the only way to find out if the catalytic converter is bad? Wouldn't that little computer monitor (I guess that is what that is) give info on the converter? When Mr. M. first hooked it up it had 8 error messages on it. When he drained the oil, cleaned the heads and refilled everything the messages were gone. I guess I will have to be patient and see what he finds out.
 

Last edited by jda; 12-19-03 at 03:37 AM.
  #11  
Old 12-17-03, 07:49 PM
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Those converters are about $790.00 each from the dealer. You have 2. They may be cheaper on the aftermarket, but cant say that for sure.
Billy
 
  #12  
Old 12-17-03, 07:56 PM
jda
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Billy,
Do you know a BMW certified mechanic you could recommend?
 
  #13  
Old 12-17-03, 07:59 PM
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You dont need BMW certified, but if you insist take it to Performance out on 15-501 across from Lowes.
Billy
 
  #14  
Old 12-17-03, 08:04 PM
jda
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I'd rather not go there. Bad experience a few years back. Do you have a couple of people you could recommend? Why do we not have to use someone who is certified?
 
  #15  
Old 12-17-03, 08:06 PM
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LOL... Because Certifications are overrated. No offense to anyone who is certified in anything. I have certifications, but I dont flaunt them.
Billy
 
  #16  
Old 12-17-03, 08:59 PM
mcourson
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common problem

This bmw has a valve on the back of the intake that goes bad and causes this problem..your husband changing the oil only brought a old problem to light..
 
  #17  
Old 12-18-03, 02:57 PM
jda
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Ok, thanks for the info. Just so we do not go into this blind, how do we know the valve is bad? And, if this was an old problem how could it be covered up? We bought the car four months ago and haven't had any problems until now.
Like Billy said, we need to make sure we know what the problem is before we start replacing things.

P.S. We changed from petroleum oil to synthetic oil. Could this have caused any problems?
 
  #18  
Old 12-18-03, 07:11 PM
mcourson
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if you look at the front of the engine and see the throttle body you have to take it off,when you do the front of the intake will be open.Just shine a light in the front of the intake and see if it is full of oil...if it is the valve is bad...
 
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