SOLVED: 2003 X5, 3.0l, runs rough, reset on restart?
 

Hello,

I know some of the symptoms I'm about to describe have been listed elsewhere in this forum, but I've been unable to find a description close to what I'm experiencing. If a solution is on another post, please feel free to direct me there.

Issue: Every so often, my X5 will run EXTREMELY rough, almost as if all cylinders are misfiring. No power, sputtering like crazy, etc. This only happens when the car is at idle and it doesn't matter if the car is warm or cold. It starts with a barely perceptible change in idle RPM then, upon stepping on the accelerator, the car sputters bad. Turning the ignition off, then right back on immediately solves the problem. Again, this always starts at an idle, not while driving. Example: I pull into a store parking lot the other day and sit with the car idling while checking my phone. RPM's drop from around 1000 to about 800 with a barely noticeable change in engine sound. I go to pull out and the engine is sputtering. I stop, shut the car off, and restart and everything is fine. The really strange part is the only code being thrown is a "Misfire, cylinder #2". Now, I've driven a car with 1 cylinder down before and it wasn't nearly as bad as what my X5 is doing. I can't believe that the sputtering that is happening is due to 1 cylinder misfiring, but I have been known to be wrong plenty of times before.

Here's what's been done recently: DISA valve rebuilt, spark plugs changed, intake boots and air filter checked. I just recently purchased this car and, when I changed the spark plugs, I saw evidence that someone had switched coils on Cylinder 1 & 2 in an effort to solve the issue.

Seems like an electrical problem over a vacuum issue because a restart of the car always fixes the problem.

Any help would be appreciated and, again, my apologies if this issue has been addressed elsewhere.

Are your check engine or service engine soon lights working? There have been postings from other new X owners that reported that the previous owner has either tape over these light or remove them from the dash so that they wouldn't be illuminated when a perspective buyer came to look at the truck. Shutting down and restarting tells me that you have a misfire or several misfires that the DME/ECU has recorded and is shutting down the injector(s) to prevent damage to the cats. Restarting the engine just restart the misfire counter in the DME/ECU until it reaches a certain count and then it shuts the injector(s) again.

Yes, SES light is working and that's how I knew to scan for the "Misfire, cylinder #2 code".

Interesting information. I didn't know the computer would shut down an injector after a certain number of misfires. Looks like my next step is to swap a coil pack with another cylinder and see if the issue follows the coil, which I should be able to do tonight.

Again, it seems to me that the sputtering is much more rough than what would be experienced with 1 cylinder out, but I don't have direct experience with this in an X5 and a straight 6 as this has.

Will post more after coil swap.

When a coil pack goes bad, you'd think the engine was going to shake itself out of the car. In addition to running really rough, there is a very noticeable drop in power.

It feels almost dangerous to drive. If you have a misfire code, it might be the coil. Cheap part, easy to swap out.

It is almost hard to believe how badly one bad coil can affect the performance.

Another question for you: Does the computer only shut the injector down after a certain amount of misfires AND only when the car is stopped? That would make sense from a safety standpoint and would further point to an actual issue in Cylinder #2.

I've no clue, but upallnight can probably answer.

The computer shuts down the injector only after a certain number of misfires has been recorded. The computer will shut down the injector even if the car is moving. When the injector is shut down, the computer will turn on the service engine light.

The counter is reset when the engine is turned off. The service engine soon light may go off when the engine is shut down and restarted but will come back on when the injector is turn off by the computer.

upallnight,

Thanks for the information. I have never once had the X5 shut off the injector and run rough while driving. Every single time has been at idle. Once in driveway, twice at redlights, once at store, etc. Is it possible that the coil in cylinder #2 is only misfiring at low RPM's and thus hits the counter only when in idle? Have you ever seen this behavior before?

Picking up a new coil in an hour so this post may be moot, but it would still be great information to know.

Did you ever have a SES light come on while you were driving the car? I had a bad coil one time while I was driving the X. The SES light came on. I carry a bluetooth scanner in the car and use an app on my phone to scan the car. It was for a misfire in cylinder number 2. Swap the coil with another cylinder and clear the code. Drove the X for a while and the SES light came on again. Scanned the car again and the misfire moved to cylinder 3. Bought a new coil at the local auto part store and replace the bad coil. Been fine for the past 4 years.

Along with many others on the forum we all can toss out ideas of what we think the cause of your intermittant issue= this failed component. However as posted, the only way to see what is going on at this point requires you to tap into to the data stream to read "live"/captured activity as the on-board systems try to compensate for the problem. You can see injectors pulse increase/decrease, secondary ignition activity by cyl, etc, ect. All of this will help you and the collective knowledge of our community provide insight on the point of the issue.
Example: it maybe poor fuel causing an issue with a clean burn in the cylinders, or a bad injector/connection turning off fuel flow to a particular cyl, or even a bad coil/wiring pinched that fails. Who knows...
Everything at this stage with out real info is just a SWAG (Scientific Wild Ass Guess) So, based on that thought, my SWAG guess is TPS/Intake Cam Sensor related.

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