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7 Series - E38 (1995 - 2001)

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  #1  
Old 09-18-2011, 10:22 AM
liam devine liam devine is offline
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Location: South Carolina
 
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Mein Auto: BWM 1997 740 IL
Unhappy 97 740iL - Rough idle

hi,
I need some help in troubleshooting, I have a 97 740il with 257K that runs great, or was running great until the other day. I notice it seemed to be vibrating quite badly while sitting at a red light, when i accelerated the check engine light started flashing. I replaced the spark plugs, which seemed to help somewhat, and fixed the vacum leaks in the MAF system, took it to advanced and it produced the camshaft position sensor code which said it was missfiring on cylinder 7. Before i drop the hundred bucks to replace it, is there anything else i should check that could be casing the rough idle before I spend the money? I would love to talk to someone one on one about this.
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  #2  
Old 09-18-2011, 03:50 PM
A.J.M. A.J.M. is offline
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Location: saint louis
 
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Mein Auto: 740IL
i had a similar situation but replacing the sparks did the trick. check the wires, coils, and distributor. make sure there isnt any oil in or around the plugs.
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  #3  
Old 09-18-2011, 04:06 PM
liam devine liam devine is offline
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Location: South Carolina
 
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Mein Auto: BWM 1997 740 IL
There was alot of oil around the plugs, but I made sure they where good and clean before putting in the new ones. Can you tell me if there is two cam position sensor on this car or just one? the code was p0307 and it said there was a missfire on cylinder 7. It does seem to be running better but not like it should any help would be greatly appreciated as I am about to loose my marbles!!
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  #4  
Old 09-18-2011, 05:43 PM
fredsta170 fredsta170 is offline
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Location: Bronx, New York
 
Join Date: May 2011
Posts: 47
Mein Auto: 740i - 1999
I just also puscahsed a 740i 1999, the idle is fine but as I excelerates it studders a bit, I'm waiting until I burn all the gas in the tank, I will add a fuel injector cleaner to full tank of gas and change spark plugs soon. Khios this will eliminate the problem?

Im not able to fully drive it yet, I had some issues with the license but all squred at the end of the month can't wait.

Keep me posted I'll do the same.
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  #5  
Old 09-18-2011, 06:07 PM
fredsta170 fredsta170 is offline
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Location: Bronx, New York
 
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Mein Auto: 740i - 1999
Oops I meant to say (that I hope replacing spark plugs and adding an injector cleaner would improve and eliminate the sluggish start. I'm also concern it could be sensor? Ie oxygen, octane sensor etc?
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  #6  
Old 09-18-2011, 06:15 PM
A.J.M. A.J.M. is offline
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Location: saint louis
 
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Mein Auto: 740IL
if there is oil, you have to replace the head gasket. do you notice any smoke on your start up?

and fredsta, i would do the spark plugs and then check to see what code its throwing (if any)
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  #7  
Old 09-18-2011, 06:20 PM
liam devine liam devine is offline
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Location: South Carolina
 
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Mein Auto: BWM 1997 740 IL
has anyone ever had the P0307 code come up and if so what was done to fix it?
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  #8  
Old 09-19-2011, 05:40 PM
fredsta170 fredsta170 is offline
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Location: Bronx, New York
 
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Mein Auto: 740i - 1999
You know something I did have oil around the spark plug on all four cylinders, I dried up the area on the driver side. I'll check the passenger side of the engine as well. I though that this could be a possibility as well. I also order a new oil cap for the engine I think the gasket is worn and dried out after 200,000 miles.

Can we use a wire cleaner on the wire spark plug connection to assure that the connections are clean?
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  #9  
Old 09-19-2011, 05:43 PM
fredsta170 fredsta170 is offline
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Location: Bronx, New York
 
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Mein Auto: 740i - 1999
Copy A.J.M which obc reader that's affordable you recommend?
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  #10  
Old 09-21-2011, 11:09 AM
bluebee's Avatar
bluebee bluebee is offline
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Location: San Jose, California
 
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Mein Auto: 02 BMW 525i M54 automatic
Quote:
Originally Posted by fredsta170 View Post
Copy A.J.M which obc reader that's affordable you recommend?
We wrote this for the E39, but for all cars with the OBD2 diagnostic port, I would think the tools would be the same.
- Cheapest CAN OBDII scanner on the net that reads DTCs, pending codes, & clears codes



As for the misfire, maybe this diagnostic tree from the E39 bestlinks will help on the E38:
- How to diagnose a BMW engine misfire (1)
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  #11  
Old 09-21-2011, 06:03 PM
silverhair silverhair is offline
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Mein Auto: 98 740i
Try cleaning your MAF sensor.
Switch #7 with another coil and see if it follows.
Change your valve cover gaskets. (not your head gasket)
Change your fuel filter and or regulator.
Air cleaner?

Just some ideas.
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  #12  
Old 09-21-2011, 08:12 PM
balance balance is offline
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Mein Auto: 97 740iL
I would agree with bluebee and silver hair on this. A flashing CEL means there is a severe misfire.

-Oil around the plugs means the Valve Cover gaskets are bad, and should be replaced before the oil fouls the new plugs like it did the old ones.

-Switch both the coil and the spark plug of cylinder 7 with the coil and plug of another cylinder and see if the code follows. It would be even better if you swap the coil to a different cylinder than the plug.

-Some may disagree with this, but if the shake and vibration happens at idle, personally, I'd disconnect the cam position sensor while the motor is at idle, and see if the shake is still there. If it is, I would think that the problem is coming from somewhere else.

The catalytic converters are known to go bad on these cars, and if a chunk of the material in the cat has broken off and clogged the exhuast pipe, that could cause some issues with misfires, so that is another possibility, but I would start by checking what was recommended by bluebee and silverhair.

Last edited by balance; 09-21-2011 at 08:14 PM.
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  #13  
Old 01-18-2012, 05:29 AM
mrmanmn mrmanmn is offline
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Location: Washington DC
 
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Mein Auto: '96 750il
Missfire Code(s) - a little rough idle

Hi - i have same issue.

I have '96 750il - 200K.
The misfire code(s) for all cylinders just appeared recently and I have noticed a little rough idling too. The missfiring issue happens only in the morning, I could say when it's cold (it's winter here in VA). When the car warmed up, I reset the code & drive all day w/out new codes.

What I have done within a year:

(4) O2 sensors replaced (did not clear code P0104).
Air filters changed.
ATF & Filter changed due to P0740 code (did not clear P0740).
(2) MAFs replaced (cleared both codes P0140 & P0740).

Code P0300's appeared and the following was done:
Changed new Battery
Changed all plugs (old ones looked normal)
Changed Caps & Rotors
Changed (2) Coils (mine has 2 coils not 12)

I checked all vacuum by spray "starting fluid" on hose

I'm kind of hold-off on the spark plug wire since it's cost $500 for the wires

I still have the misfiring codes - what else can I check?

Thanks in advance for you advice(s)

ManN

Last edited by mrmanmn; 01-18-2012 at 05:46 AM.
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  #14  
Old 01-18-2012, 05:45 AM
mrmanmn mrmanmn is offline
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Location: Washington DC
 
Join Date: Jan 2012
Posts: 7
Mein Auto: '96 750il
Missfire Code(s) - a little rough idle

Hi - I have same issue.

I have '96 750il - 200K.
The misfire code(s) for all cylinders just appeared recently and I have noticed a little rough idling too. The misfiring issue happens only in the morning, I could say when it's cold (it's winter here in VA). When the car warmed up, I reset the code & drive all day w/out new codes.

What I have done within a year:

(4) O2 sensors replaced (did not clear code P0104).
Air filters changed.
ATF & Filter changed due to P0740 code (did not clear P0740).
(2) MAFs replaced (cleared both codes P0140 & P0740).

Code P0300's appeared and the following was done:
Changed new Battery
Changed all plugs (old ones looked normal)
Changed Caps & Rotors
Changed (2) Coils (mine has 2 coils not 12)

I checked all vacuum by spray "starting fluid" on hose

I'm kind of hold-off on the spark plug wire since it's cost $500 for the wires

I still have the misfiring codes - what else can I check?

Thanks in advance for you advice(s)

ManN
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  #15  
Old 01-18-2012, 06:21 PM
silverhair silverhair is offline
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Location: Grand Rapids, Michigan
 
Join Date: Dec 2010
Posts: 126
Mein Auto: 98 740i
Have you considered bad cats?

It's a long read, but check out this thread.

http://www.bimmerfest.com/forums/sho...d.php?t=470150
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  #16  
Old 01-18-2012, 08:40 PM
Cityconstable Cityconstable is offline
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Location: Boston ma.
 
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Mein Auto: 1997 z3 2.8
I just replaced my cam position sensor

Took 5 minutes and 120.00 but the roughness went by by (97 740)
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  #17  
Old 01-19-2012, 03:31 AM
mrmanmn mrmanmn is offline
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Location: Washington DC
 
Join Date: Jan 2012
Posts: 7
Mein Auto: '96 750il
Thanks for the tip... I'll look into that CATs... I'll post the result to share with everyone.

MrManN
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  #18  
Old 01-19-2012, 03:45 AM
mrmanmn mrmanmn is offline
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Location: Washington DC
 
Join Date: Jan 2012
Posts: 7
Mein Auto: '96 750il
OMG - the CATs are ranging from $80 to $800! Which should I get? I plan to keep this vehicle for another year to teach my kids to drive (it's the safest car!)

MrManN
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  #19  
Old 01-19-2012, 04:36 PM
silverhair silverhair is offline
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Location: Grand Rapids, Michigan
 
Join Date: Dec 2010
Posts: 126
Mein Auto: 98 740i
I replaced with Magnaflow high flow. About 70 bucks here locally.
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