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X3 E83 (2004 - 2010)
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  #1  
Old 10-20-2011, 10:10 PM
Elskunk Elskunk is offline
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Mein Auto: 07' BMW X3
Fluctuating RPMs, Rough Idle, and Engine Light

Hey everyone, this is my first thread on the forum so if there are issues with this post please let me know.

I recently bought a new to me, 2007 BMW X3 from a local dealer here in St. Louis, MO. Everything was going great with the new ride until a random anomaly started to occur (my wife is the primary driver, so the discovery was new to me, but may have been present for some time now). The anomaly was a fluctuating RPM gauge upon idle, the truck would start normally but would pulse downwards for a instant and then resume to normal. The fluctuation would occur during warm and cold days and even after the car had sufficient time to properly warm up. I even took it for a long road trip 1,000 + miles only stopping for gas and it would still fluctuate when stopped at a red light. At this point in time no engine light was present nor rough/shacking vibrations.

I attributed the the RPM to a possible vacuum leak from the CCV and did a recommended trick (plastic bag over the filler cap when the engine was idling to ensure a vacuum) so I moved onwards trying to figure the thing out. I have been searching what to do and with no luck couldn't diagnosis the problem. I was about to take the X3 to reputable Indy shop but then something was added to list of symptoms. The check engine light came on, which may seem like a problem getting worse but now I have a logical point to start from.

The check engine light came on the other morning after the temperature dropped the night before with hours of cold rain. Once again I thought of the CCV with the moisture and the cold weather. I went to Autozone to have the codes read because I have not had adequate time to purchase a PEAK scanner. The truck now vibrates badly with a significant drop in power.

Here are the codes:

P2068 - Fuel Level Sensor B (Circuit High Input)
P0463 - Fuel Level Sensor A (Circuit High Input)
P0305 - Cylinder 5 Misfire

I then proceeded with a multimeter to the fuel level sensor to measure the resistance each sensor was giving.

Here are the results:

Right Fuel Sensor (Driver Side, Yellow Plug) 60 Ohm ~ Empty and 280 Ohm Full
Left Fuel Sensor (Passenger Side, Blue Plug) 60 Ohm ~ Empty and 353 Ohm Full

The wiring harness plugging into the Fuel housing resulted at .2V for both Fuel Sensors and .0v for the Power and Ground; The resistance for each switch was 972 Ohm. Not sure if I need to check the wiring harness but I was there so I figured too much information never hurts.

The On Board Computer, using the hidden testing, Test #6 found that this 1_6.2 indicating both sensors are okay. This really threw me off, the OBC indicated both sensors are okay but by lifting the float in the tank to simulate a full tank resulted in two different resistance levels 280 vs. 353 Ohms.

I need additional help, can someone please recommend the next step. I have also dumped (2) bottles of Techron through the motor on two separate occasions and have only filled up with 93 octane gas 10+ full-tank fill-ups and also ran a bottle of injector cleaner through for good measure. The truck has 44,000 miles on it and I have no indication of previous service records except a 30,000 done at the dealer. According to the Vehicle Title it was registered in Florida and Georgia area before being bought by me in St. Louis.

If the vehicle is parked or stopped on a incline in either direction the fluctuating RPM happens more frequently, every 10-15 seconds opposed to the normal 30-45 seconds. Immediately after filling up with 93 octane gas the fluctuating stopped for a few miles prior to the check engine light appearing. My wife also recalls never seeing the low fuel light ever being lit.

All symptoms point me in the direction of changing the right fuel sensor, except the OBC. Can someone please shed some light on me. Thanks.
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  #2  
Old 10-21-2011, 08:32 AM
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timfitz63 timfitz63 is offline
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Speculation on my part, but the fuel level sensor codes could be old and not applicable to your current bout of 'rough-running engine.' I'm also skeptical that bad fuel level sensors would cause the engine to run poorly -- but it wouldn't be the first time that I got 'fooled' by some strange connection between seemingly unrelated components/symptoms...

The misfire code could be current and valid. The problem initially struck me as vacuum-related as well, but after reading 'the rest of the story,' I'm starting to think fuel delivery... Maybe the fuel pump is going out on you...?
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  #3  
Old 10-21-2011, 11:11 AM
Elskunk Elskunk is offline
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timfitz63.

I will proceed to check the fuel pump to make sure it is getting adequate voltage. I don't have a fuel pressure gauge to check the fuel psi on the fuel rail. While I'm at it, I will check the resistance of all the fuel injectors by starting with cylinder 5 and working my way through a few more. Checking 2-3 others should give me an adequate benchmark for a failing injector.

I know the fuel pump is not entirely dead, but possibly failing.

To simplify my initial thread post. The symptoms were sensitive to:

-Temperature
-Angle of Incline
-Warm vs. Cold motor have no change of impact
-Possibly fuel level in tank ~ could be coincidental

Can anyone verify that the left and right fuel level senders have different full resistance. I don't have access to a repair manual at this time (No CD from eBay, yet). From reading others' posts it appears that the left and right fuel sending units resistance should be the same but have yet to find information regarding the X3, maybe due to the limited number of users with repair manuals.
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  #4  
Old 10-21-2011, 02:29 PM
fivepointnine fivepointnine is offline
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stupid question, but have you tried cleaning your MAF, checking your intake boot and cleaning your IACV? sounds like the symptoms of a CCV, but not the codes I got when mine failed......
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  #5  
Old 10-22-2011, 04:29 PM
Elskunk Elskunk is offline
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Update today. I checked the resistance on 5 of 6 the fuel injectors, didn't feel like measuring the one closest to the fire wall. My readings were 12.2 on (2) and 12.4 on the other (3). Fuel Injectors are not the issue.

Had the codes read again today just after messing with everything and I was able to drop p2068 Fuel Level Sensor (Circuit High Input), therefore I still have P0463 - Fuel Level Sensor A (Circuit High Input) and P0305 - Cylinder 5 Misfire.

fivepointnine.

I tried to clean the Idle Air Control Valve (IACV), but I could not find it . This is my first BMW and I'm not familiar with the engine build. I did some preliminary searching online and could not find a photo reference for a 07' X3, sure I can find location photos for other BMW makes but they did not help me to locate the IACV on a X3. I inspected the intake boot and there are no rips or tears. I did not clean the MAF, I heard a few people mentioning it ruins the electrical connections; even though this is common practice in the field I opted not to. I would have seem a lean condition or O2 sensor codes from both banks if the MAF was the culprit.

Does anyone know which fuel level sensor is responsible for sending a signal to the cluster indicating the fuel reserve is being consumed, i.e. 2-3 gallons left in the tank before empty?
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  #6  
Old 10-22-2011, 04:54 PM
Elskunk Elskunk is offline
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Video of the fluctuating idle as it pulses downwards. Sorry for AC air sound.



You can also see the low fuel light coming on when key is positioned in "On" position.
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  #7  
Old 10-22-2011, 05:23 PM
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timfitz63 timfitz63 is offline
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Mein Auto: 2007 X3 (MT)
I guess I wouldn't call that RPM fluctuation abnormal, but I also can't hear or feel the engine running in the video, so I couldn't say if that would alter my perception. Since you have a SES light, there's obviously something amiss...

The 'Fuel Low' light coming on when you initially turn on the key/start the engine is normal, I believe; this is just part of the standard gauge cluster light check that's performed on every start-up. The codes for the fuel level sensors might be coincidental at this stage; and since one has already cleared, the other might also after a number of successful start cycles without whatever error caused it in the first place.

Apparently I'm not going to be of very much help to you in troubleshooting this SES... Sorry!
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  #8  
Old 10-22-2011, 06:05 PM
Elskunk Elskunk is offline
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When I mentioned the fuel light on, I was inferring that the bulb is not burnt out. If everything was normal when the tank is near empty and the truck is running off of the reserve fuel (2-3 gallons) the light should normally be lit, indicating the low fuel.

No matter what is causing the cylinder #5 misfire, I have a continuity issue with the fuel sensor. Somewhere between the sensor and the cluster the ground is not properly functioning. I could assume this to be the faulty Fuel Sensor A and attribute the misfire to it, but I don't dare assume just yet.

Instead of throwing parts/time/money at the situation, I have determined it is beyond my skill level. I will be seeking help from an actual mechanic in the next coming days. I hate to do it but with a little math its not worth the gamble.
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  #9  
Old 10-22-2011, 11:09 PM
fivepointnine fivepointnine is offline
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IACV is located above your throttle body, you need to pull off your intake boot and DISA to get to it.
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  #10  
Old 10-23-2011, 02:45 AM
Elskunk Elskunk is offline
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Thanks fivepointnine.

I actually pulled the DISA half way out to inspect the gasket for flat spots, it was right in front of me the entire time, I even removed the throttle body. Upon removal of the throttle body I noticed a ring of oil concentrated along the bottom of the seal, the amount wasn't a lot but I did notice it. Could oil along the throttle body be a telltale sign of a failing CCV, how much is considered tolerable? Either way the sign of oil up to the throttle body means I need to clean the IACV with some brake cleaner.
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  #11  
Old 05-20-2015, 09:45 AM
e83__2008 e83__2008 is offline
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Elkskunk,

Did you ever figure out what went wrong here? It sounds like I'm having the same issue with my '08 x3... it was running fine 2 days ago, then yesterday morning when I started it up, all of this started happening out of nowhere. Same symptoms, check engine light, pretty rough idle, rough when trying to accelerate up hill (not as much power and shaky).

Last edited by e83__2008; 05-20-2015 at 09:56 AM.
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  #12  
Old 05-20-2015, 10:25 AM
joylove joylove is offline
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Quote:
Originally Posted by e83__2008 View Post
Elkskunk,

Did you ever figure out what went wrong here? It sounds like I'm having the same issue with my '08 x3... it was running fine 2 days ago, then yesterday morning when I started it up, all of this started happening out of nowhere. Same symptoms, check engine light, pretty rough idle, rough when trying to accelerate up hill (not as much power and shaky).

Guesswork is for the 1970s. Get a BMW C110 code reader. Chances are it's a coil pack. Since you are probably at around 100k miles it's time to change the fluids in the gearbox, diff and transfer box, using only BMW fluids for the latter.
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  #13  
Old 05-20-2015, 10:32 AM
e83__2008 e83__2008 is offline
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Thanks, and yeah I'm going to see what codes pop up today. Just wanted to check what the diagnosis was for others
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  #14  
Old 05-20-2015, 12:50 PM
SonicBoom SonicBoom is offline
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Quote:
Originally Posted by fivepointnine View Post
IACV is located above your throttle body, you need to pull off your intake boot and DISA to get to it.
Wait a minute...

The N52 has a IACV??? I thought the valvetronic did the metering.

I know we have a throttle plate, but I thought that was only used during warm up.
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  #15  
Old 05-25-2015, 05:47 AM
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jdeday jdeday is offline
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Have you switch the coils around to see if you receive the misfire on a different cylinder?
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  #16  
Old Today, 12:38 PM
BMW X3 HUN BMW X3 HUN is offline
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Quote:
Originally Posted by e83__2008 View Post
Thanks, and yeah I'm going to see what codes pop up today. Just wanted to check what the diagnosis was for others
Can you write that, what was the solution? I have the same problem with my 2008 E83! Ty!
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  #17  
Old Today, 12:39 PM
BMW X3 HUN BMW X3 HUN is offline
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Quote:
Originally Posted by Elskunk View Post
Hey everyone, this is my first thread on the forum so if there are issues with this post please let me know.

I recently bought a new to me, 2007 BMW X3 from a local dealer here in St. Louis, MO. Everything was going great with the new ride until a random anomaly started to occur (my wife is the primary driver, so the discovery was new to me, but may have been present for some time now). The anomaly was a fluctuating RPM gauge upon idle, the truck would start normally but would pulse downwards for a instant and then resume to normal. The fluctuation would occur during warm and cold days and even after the car had sufficient time to properly warm up. I even took it for a long road trip 1,000 + miles only stopping for gas and it would still fluctuate when stopped at a red light. At this point in time no engine light was present nor rough/shacking vibrations.

I attributed the the RPM to a possible vacuum leak from the CCV and did a recommended trick (plastic bag over the filler cap when the engine was idling to ensure a vacuum) so I moved onwards trying to figure the thing out. I have been searching what to do and with no luck couldn't diagnosis the problem. I was about to take the X3 to reputable Indy shop but then something was added to list of symptoms. The check engine light came on, which may seem like a problem getting worse but now I have a logical point to start from.

The check engine light came on the other morning after the temperature dropped the night before with hours of cold rain. Once again I thought of the CCV with the moisture and the cold weather. I went to Autozone to have the codes read because I have not had adequate time to purchase a PEAK scanner. The truck now vibrates badly with a significant drop in power.

Here are the codes:

P2068 - Fuel Level Sensor B (Circuit High Input)
P0463 - Fuel Level Sensor A (Circuit High Input)
P0305 - Cylinder 5 Misfire

I then proceeded with a multimeter to the fuel level sensor to measure the resistance each sensor was giving.

Here are the results:

Right Fuel Sensor (Driver Side, Yellow Plug) 60 Ohm ~ Empty and 280 Ohm Full
Left Fuel Sensor (Passenger Side, Blue Plug) 60 Ohm ~ Empty and 353 Ohm Full

The wiring harness plugging into the Fuel housing resulted at .2V for both Fuel Sensors and .0v for the Power and Ground; The resistance for each switch was 972 Ohm. Not sure if I need to check the wiring harness but I was there so I figured too much information never hurts.

The On Board Computer, using the hidden testing, Test #6 found that this 1_6.2 indicating both sensors are okay. This really threw me off, the OBC indicated both sensors are okay but by lifting the float in the tank to simulate a full tank resulted in two different resistance levels 280 vs. 353 Ohms.

I need additional help, can someone please recommend the next step. I have also dumped (2) bottles of Techron through the motor on two separate occasions and have only filled up with 93 octane gas 10+ full-tank fill-ups and also ran a bottle of injector cleaner through for good measure. The truck has 44,000 miles on it and I have no indication of previous service records except a 30,000 done at the dealer. According to the Vehicle Title it was registered in Florida and Georgia area before being bought by me in St. Louis.

If the vehicle is parked or stopped on a incline in either direction the fluctuating RPM happens more frequently, every 10-15 seconds opposed to the normal 30-45 seconds. Immediately after filling up with 93 octane gas the fluctuating stopped for a few miles prior to the check engine light appearing. My wife also recalls never seeing the low fuel light ever being lit.

All symptoms point me in the direction of changing the right fuel sensor, except the OBC. Can someone please shed some light on me. Thanks.
Can you write that, what was the solution? I have the same problem with my 2008 E83! Ty
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