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Kevin Halbleib 02-08-2013 07:45 PM

1995 740il Rough idle and drive
I just was driving down the interstate and all of the sudden the car seemed to start running rough. YOu can smell gas after awhile.

Seems to be kind of missing.

I did try to do the OBD1 code pull. I get code 1221. But it keeps repeating and I cannot seem to get it to quit.

Does not die, does not run hot. Easy to start.

Please help.

Espresso 02-09-2013 06:00 AM

02 sensor.
not going into closed loop mode. You are more than likely running rich & fouling plugs which make it hard to start when cold.

Kevin Halbleib 02-09-2013 06:27 AM

Can I just unplug or do I have to replace?

First740i 02-09-2013 09:20 AM

Pull your plugs! First thing to look at. I have 160,000 miles and o2's are fine. Had that symptoms it was plugs

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Kevin Halbleib 02-09-2013 12:51 PM

I pulled the plugs and replaced. Passenger side plugs were dry and old looking. Drivers side were a little normal and a couple were some oily.

Replaced. Seemed to be no change. Car will start and run. At idle speed very rough. If I rev up at higher rpm's smooths out in driveway.

I am assuming next step is 02 sensor. However I am not sure where to start. Should I buy one or can I simply unplug to test? Any advice?

First740i 02-09-2013 06:14 PM

Id save some money and test them. Did the plugs ha a lot of ill on them? If so you need to to valve cover gaskets. As the gasket wears out over time the oil it lest in shorts out the plug sounds stupid I know but true! If there is oil puddling up around them that could very well be your problem!

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Kevin Halbleib 02-09-2013 09:05 PM

There was a little oil puddling. Not to bad. But if I put new plugs in, I would have expected a big improvement.

First740i 02-10-2013 08:42 AM

Yes i agree. I do not know!?

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Ocotillo 02-10-2013 09:14 PM

I am having the same issue on my 98 with 123k miles. I am getting a p0308 error code (misfire on cylinder 8). I have completed the following repairs but the error code still persisting and the car is rough when idle.

1. Tested spark plug coil (error did not move with coil)
2. Replaced all spark plug with Bosch Platinum+4 spark plug
3. Replaced valve cover gaskets
4 Replaced Intake manifold plate (behind engine) and the gasket
5. New fuel pump and fuel filter (for unrelated reason)

Despite all these repairs, the car is still rough when idle but otherwise runs fine when it's moving. What are the symptoms of a bad o2 sensor? Is there a way to test the o2 sensor?

BMWFatherFigure 02-10-2013 10:02 PM

I haven't heard of an O2 sensor test. Onlt thing I can think of is test resistance of all sensors hot and cold and compare results. I guess one or more will be bad. Take results from the 'good' side as correct. Maybe compare with a good known engine?

Kevin Halbleib 02-11-2013 06:18 AM

Interesting enough. I sprayed brake cleaner looking for a vacuum leak. I did get a little on top, engine reved up and I went to try and find it, but it would not repeat. Took the car for a drive and within a few minutes, it started getting better. Went for about a 45 minute drive and it is driving perfect.

I notice a very little rough idle, I still get 1222 & 1221 error codes which are o2 sensor codes. But really runs so good, I am not really worried about it. I used copper plugs and cleaned out the oil.

jitsjaf2009 02-13-2013 01:55 PM

My limited experience, you may be having a failure of your oil separator and getting oil into your intake manifold. This would cause the couple oily pluggs...usually plufs to 'rear' of intake (next to firewall. Also rough idle which smooths out with increased RPMs could indicate intake leaks or vacuum leaks. These are what I would look for first.

BMWFatherFigure 02-13-2013 06:37 PM

O2 sensors fail. Change them.

Kevin Halbleib 02-13-2013 07:40 PM

I will change the 02. Thanks to all!

First740i 02-14-2013 05:31 PM

You still have no changer o2? Holy long process you have gone trought

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Kevin Halbleib 02-14-2013 07:31 PM

I have not done anything further. 02 sensors will be next.

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