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E34 (1989 - 1995)

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  #1  
Old 01-21-2005, 09:14 PM
balboaislandbob balboaislandbob is offline
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Location: San Diego, Ca
 
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Mein Auto: 95 540i
1995 540i, Rough running at Idle????

Hi all, we just bought a 1995 540i at auction with 105,000 miles on it. My better half Sophia loves the car. It runs rough at idle (shows 750 +/- RPM). We put new spark plugs in, it passed the smog check real clean, and the compression checked out fine. Yet, it still runs rough at idle. Any thoughts out there?
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  #2  
Old 01-23-2005, 09:01 AM
JPower JPower is offline
Ultimate Driving Machine
Location: LA
 
Join Date: Mar 2004
Posts: 5
Mein Auto: E30 sleeper ( Euro. S50 )
Quote:
Originally Posted by balboaislandbob
Hi all, we just bought a 1995 540i at auction with 105,000 miles on it. My better half Sophia loves the car. It runs rough at idle (shows 750 +/- RPM). We put new spark plugs in, it passed the smog check real clean, and the compression checked out fine. Yet, it still runs rough at idle. Any thoughts out there?
most likely the engine is bad , you need to do a leak down test on the engine .
BMW V8 engines between 1993 and 1995 devolped this problem because the sulfer content in the fuel was damaging the cylinder wall coating.
Do not install a used engine most likely it will be the same, you need to buy the block from the dealer, the new blocks have been improved from BMW. Good luck
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  #3  
Old 01-23-2005, 08:50 PM
Bob in San Jose Bob in San Jose is offline
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Mein Auto: 1995 540iA
The first thing to check is if the block is Alusil or Nikasil. Go to koalasport.com, there is a good writeup there on this problem and how to check the engine block casting number to determine the block type. Even if the block is Nikasil, "The Bad Block", there is a good chance it is OK.
The problems with these engines occurred after 30K miles not 100K.
The more likely problems for erratic idle are vacuum leaks. At 100K the intake gaskets, vacuum hoses, and EGR device at the back of the engine have probably developed leaks.
I have a 95 540iA with the Alusil block, replaced the Nikasil block at 39K, that was exhibiting the same problem and I had the above gaskets and hoses replaced to fix it.
A leak down test is a good thing to do if the block is Nikasil but I would check/do the gaskets/hoses if they have never been done.

Bob
1995 540iA
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  #4  
Old 02-01-2005, 10:49 PM
Qamar Qamar is offline
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Location: United Arab emirates
 
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Posts: 3
Mein Auto: 530i, Model 1995, V-8
Stalling in your car

Hi

I have 1995 model, V-8 automatic. I had the similar problem. I had changed the 02 Sensor. Now the car is perfect. Before you change the 02 sensor pl get it checked weather it is working or not. If you know the procedure of checking it is good, otherwise let me know, i will write it back to you.

Qamar
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  #5  
Old 04-29-2006, 07:04 AM
LozinOz LozinOz is offline
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Location: Australia
 
Join Date: Apr 2006
Posts: 1
Mein Auto: 1994 540i
Smile Cure for rough idle

My 540i had a rough idle on cold starts when I bought it. Not severe at first but got worse over 12 mths. An open front door would shake severely for a minute or more after startup and then it would smooth out quite quickly, but still miss quite a bit. I was confident from BMW dealer leakdown test/compression test etc that the engine was in very good order.

Early on I replaced the cover/oil separator at back of intake manifold (without taking the manifold off) on advice from BMW that it was a common point of failure. This didn't fix the problem.

More recently, when it got too severe to leave, I replaced the intake manifold gaskets, front cover gasket, a couple of rubber seals, and had the injectors cleaned. Two injectors were slightly down on delivery and one was down 40% before they were cleaned. About a day's work all-up.

Result was outstanding - engine just purrs and idle is brilliant hot and cold. Fuel consumption went from 13.5 l/100km on a trip to 9.6.
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  #6  
Old 04-29-2006, 06:55 PM
ThoreauHD ThoreauHD is offline
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Location: Virginia
 
Join Date: Feb 2006
Posts: 682
Mein Auto: 02/1994 530i 8cylinder
02 sensor. Intake manifold gasket. Valve cover gasket. Air filter. Oil filter. 0w-40 Mobil 1 oil. Injector clean. Later- Transmission fluid/filter/seal.

Do a idle check at a BMW service center. They'll spot it quick. I bet the thing has a bit of erratic acceleration/shifting too yes? Pretty much all your rubber parts go to hell at that mileage. Don't go to a dealer for this, but a BMW independent service center. 60 and hour vs 100 an hour makes a big difference, since it'll be all labor. The parts don't cost anything.
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  #7  
Old 05-12-2006, 01:47 PM
junoon0977 junoon0977 is offline
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Location: us
 
Join Date: May 2006
Posts: 3
Mein Auto: E34
I have a 1993 525i that idled rough. Mechanic found an air leak underneath the intake manifold due to a missing O ring on the pipe that runs from Idle Valve Controller to the intake manifold. Air leaks are usually the most common reason for rough or irregular idling.
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  #8  
Old 01-27-2011, 07:07 AM
cgmattocks cgmattocks is offline
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Location: Miramar, Florida
 
Join Date: Jan 2011
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Mein Auto: 1995 BMW 540i
I have a 1995 540i that has developed a rough idle most of the times with the check engine light on. After diagnostic my mechanic says I need o2 sensors. After unplugging the mass airfow sensor the engine idles smooth. After replugging this sensor check engine light goes off and car will not idle rough for about 2 days. Then problem will recur thereafter. I am hesitant to buy 02 sensors if its not the problem.
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  #9  
Old 01-27-2011, 07:27 AM
robertobaggio20 robertobaggio20 is offline
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Mein Auto: car
This is a straightforward problem.

1. Idle control valve and its switch. Remove the valve, clean it out thoroughly with carb cleaner, clean the switch connection, spray the cleaner on the switch's leads as well, give it ten minutes to dry, reinstall and replug.

2. Vacuum leaks. When the car is running, spray carb cleaner everywhere around the intake, the air box, the air bellows/air hose leading to the throttle body and the air flow sensor, the throttle body area where it joins the manifold, the manifold at the area where it joins the cylinder head. If the idle suddenly improves, you've found your vacuum leak. What's happening is that the carb cleaner is being sucked into the leak by the engine's vacuum. It goes into the combustion chamber together with the regular airflow and combusts with the fuel. Excess fuel does not generate rough idling, only excess/unpredictable air flow does. So that's how that works.

3. Faulty air mass sensor. This is easily diagnosed. Just unplug the sensor and restart the engine. If the idle improves, then you've found your culprit. You'll either need to tune your car using a computer (if that function is available for it) or you'll need to replace the maf and clear the error codes that would've been logged on the car's computer.

4. Do the stomp test and/or otherwise pull out the error codes on your car. That could lead you to the problem straightaway.

5. #2 and 3 can be tested within 5 minutes. Try that. Then, do No 4, and then no 1. This would be in its rising order of difficulty.

6. You've just bought this car. There are many things you'll need to go through to thoroughly check out, revive and tune it up to normal. You'll have to assume its been abused. All of that will cost you money. But not to worry....pretty much everything that you do, you'll have to do anyway to keep your car in tip top shape, and if you intend to keep it for the long term. And its performance will definitely improve as a result of your thorough tuneup.

7. There are other things you can do for this car that would be classified as preventive action, which would assure you that you'll not encounter a situation where the car refuses to start and you're stuck somewhere. Basically, you'll have to replace the fuel pump, the crank sensor, the cam sensor if you have one and the relays for the dme, fuel pump and O2 sensors. This stuff could cost some money but we've found good sources on Ebay so you won't burn a hole in your pocket for the parts at least. You can keep the old ones as working spares.

8. Is your car an automatic? If so, take a sample of the transmission oil and tell us about it, but don't change it out completely yet. There are precautionary issues involved with end-of-life trannys.


Good luck and congrats on your buy. btw what was your winning bid for the car?

Last edited by robertobaggio20; 01-27-2011 at 09:27 AM.
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  #10  
Old 01-27-2011, 09:33 AM
robertobaggio20 robertobaggio20 is offline
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Mein Auto: car
Quote:
Originally Posted by cgmattocks View Post
I have a 1995 540i that has developed a rough idle most of the times with the check engine light on. After diagnostic my mechanic says I need o2 sensors. After unplugging the mass airfow sensor the engine idles smooth. After replugging this sensor check engine light goes off and car will not idle rough for about 2 days. Then problem will recur thereafter. I am hesitant to buy 02 sensors if its not the problem.
Unless you're throwing an o2 sensor code, your o2 sensors are fine. Your maf is the problem. Try this...unplug your maf, delete all the error codes on your car (read them first via the repeated stomp test...you need to stomp for each code, they don't always come out in sequence automatically)...clean out your maf and your air filter (this may be super dirty, in which case you can always change it), spray carb cleaner into the air hose connecting the maf and the throttle body, if you can, use carb cleaner to clean your throttle body as well, connect everything back, restart the car, and monitor for the next 2 weeks.

The maf needs to be cleaned VERY carefully. Hold your can of electrical contact cleaner or carb cleaner at a distance and spray it at the maf in a staccato fashion (on, off on off rapidly). Do this from both ends. Let the cleaner evaporate off then reinstall.
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  #11  
Old 03-10-2013, 10:44 AM
mjmike93 mjmike93 is offline
Big Mike & his E39 540Ia
Location: Mahopac, New York
 
Join Date: Mar 2013
Posts: 22
Mein Auto: 1997 BMW 540i
Hello Everybody,
I have a 1997 540iA with some of the problems listed above, a friend leant me his smoke leak detector (awesome machine) detected front intake manifold leak right away. Disassembled the intake and found gasket brittle, great I found the easy fix so I thought... Went to local BMW dealer picked und new 11 61 1 729 727, when I installed the gasket into the channel it barely stuck out of the channel and sure enough after assembling and checking it leaks worse than the old one. Has anyone else had this issue?
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  #12  
Old 03-11-2013, 06:00 PM
mjmike93 mjmike93 is offline
Big Mike & his E39 540Ia
Location: Mahopac, New York
 
Join Date: Mar 2013
Posts: 22
Mein Auto: 1997 BMW 540i
Wrong Gasket

I went back to stealer after some research and explained that the item they gave me was the rear intake manifold gasket that the front was thicker and had a dimple on the bottom. They checked and found the wrong parts had gotten into the bin since they are almost identical I understood and they were very apologetic. The counter dude at the stealership asked several times did I need anything else so I mentioned I could use four of the seals for the oil coolers and he gave them to me no charge. Good way to keep me coming back.
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