[mmns999]

Hi Everyone,
I've done all the Googling I can but can't seem to find someone else that has had the same issue I have, so I thought I would reach out here.

I have a new to me 2011 x3 28i xDrive (i.e. the N52) at around 96,000 miles. When the car comes to a stop at a red light, it some times shudders/has a rough idle as if the engine is misfiring (though I feel like it is starting to happen more frequently). The first time it happened, it felt like some one rear ended/tapped the rear of the car. When it happens the RPMs will blip higher, from a steady 600 to ~1,000 or a tad under.

The car is not throwing any CELs, seems to get normal MPG (~23 mpg, mostly city), and does not hesitate when accelerating. The car also shows no issue when it is moving. There is also no difference with AC off or on.

I am stumped and can't seem to find the cause; I wish it would just throw a CEL so I know what is exactly wrong with it. The following is what I have done to see what could be wrong:

• I have read online that it could be a faulty MAF sensor, but that doesn't seem to be the culprit. I have switched the MAF with a different one, cleaned it, and also unplugged the thing to see if the car runs differently, but none of that worked, still has the shuddering at the lights.
• I've inspected all the inlet hoses to the throttle body and there are no cracks. Put in a a new air filter.
• There are no leaks along the head gasket that I can see.
• The coils and spark plugs do not have any oil in the chamber.
• No signs of oil around the air inlets from the intake manifold to the engine or around the throttle body (so I don't think its a ruptured PCV system, but I could be wrong).

The previous owner has had some of coils and spark plugs changed (I think only pistons 2 and 4 or something like that; I think he didn't change all of them because his mechanic was taking him for a ride with the pricing he was charging off of parts and labor from what I can tell of the receipts). I am hesitant to change all the coils and plugs since there is no misfire CEL. The O2 sensors and battery was also recently replaced. Finally, I believe the TC and diff fluids have not been changed (could that be it?)

Does anyone have any idea what it can be? What could be causing all this without a CEL?

I'm thinking of actually taking off the intake manifold to check for cracks when I have the time. Does anyone know how to get the electronics off of it (I think its the DME)?

Any input is appreciated!

Cheers,
mmns

[pungo]

Have you used a proper scanner (i.e. ISTA+) to check for error(s) that don't throw a CEL?

[brianhinton77]

At 96k , and new to you, and if you don't have service records, I would change all plugs and coils. I would then do a full fluid change, Engine Oil, Transfer Case, both Diffs , and a transmission drain and fill…..NOT a FLUSH. These are of course my opinions, but this is my ritual on any car I get that is new to me….something that is easy to do and gives peace of mind

[MSport_Jon]

Service everything that can be serviced. Use OE or OEM. Do not go eBay or Ali express on this. Leaks can only be tested by a smoke machine. Visual inspections for intake leaks are useless. There should be two MAP sensors In your vehicle. One is close to the filter and another much closer to the manifold.

Your issue looks more on the engine side than the transmission. If you can replicate the problem with specific driving behavior, test the transmission by placing it on Neutral the next time you want to invoke the problem. If it still does it, it is likely your engine's ignition.

[Opie55]

A traditional CEL is one that can be read with a standard OBDII scanner and gives a code that is universal between all car makes. It does not even "see" most of the modules in a modern car, and was never intended to. Once you get a BMW-specific scan tool you'll be stunned how many modules it reads. A car can have hundreds of stored error codes and not have a CEL.

[mmns999]

Thanks for all the replies everyone. I am glad to see that the F25 forum is active.

Originally Posted by pungo

Have you used a proper scanner (i.e. ISTA+) to check for error(s) that don't throw a CEL?

I have not used a proper scan tool since I don't have access to one as a I just moved to a new area. I am trying to do all the self diagnosis I can before sending in the big guns.

Originally Posted by brianhinton77

At 96k , and new to you, and if you don't have service records, I would change all plugs and coils. I would then do a full fluid change, Engine Oil, Transfer Case, both Diffs , and a transmission drain and fill…..NOT a FLUSH. These are of course my opinions, but this is my ritual on any car I get that is new to me….something that is easy to do and gives peace of mind

This was always the plan. I have previous service records but the previous owner said that its not complete. I was planning on doing all the fluids in 2k miles as that's when the next oil change is, but that may have to be sooner rather than later. Same with the ignition stuff. May I ask, why just a drain and fill and not a flush?

Originally Posted by MSport_Jon

Service everything that can be serviced. Use OE or OEM. Do not go eBay or Ali express on this. Leaks can only be tested by a smoke machine. Visual inspections for intake leaks are useless. There should be two MAP sensors In your vehicle. One is close to the filter and another much closer to the manifold.

Your issue looks more on the engine side than the transmission. If you can replicate the problem with specific driving behavior, test the transmission by placing it on Neutral the next time you want to invoke the problem. If it still does it, it is likely your engine's ignition.

Funny (or not so funny in my case) enough, I plan to do a visual inspection because when I was first diagnosing this problem, my first thought was to check the air filter since it's easy to do and it could have been a clogged filter or something simple. When I took out the airbox, the damn thing was cracked! The metal ring post MAF sensor was also bent out of shape. Honestly, I have no idea what could have cause such a failure. I replaced the airbox since I thought that the leak was causing the shuddering and obviously because I don't want a bunch of unfiltered air heading towards the intake. But sadly it wasn't. That's why I am planning to do a visual inspection to see if there are any other major crack like that. I agree that a smoke test is the way to go, but would rather do as much as I can before sending it to a mechanic.

To your other point, the problem still persists when in neutral and park. Which I agree indicates is an engine problem rather than transmission. I should have mentioned that in my original post. I admit that I am getting a bit flustered with this, but such is life owning a BMW!

Originally Posted by Opie55

A traditional CEL is one that can be read with a standard OBDII scanner and gives a code that is universal between all car makes. It does not even "see" most of the modules in a modern car, and was never intended to. Once you get a BMW-specific scan tool you'll be stunned how many modules it reads. A car can have hundreds of stored error codes and not have a CEL.

I agree with you and pungo. I have heard of tools such as ISTA and INPA, but have not looked into it much. Is this an expensive investment? If it is, are there any other tools that do, say, 80% of the job? I've read that tools like ISTA require downloading software onto a laptop and has a steep learning curve. This is the first time where I might have to get a scan tool. I own and owned other BMWs before but have never had the need for such advance diagnostics.


In general, would this be as simple as needing new coils and spark plugs? The issue has been persistent for about 2 weeks now and I thought that if it was ignition, it would have thrown a CEL by now. Right? I would rather not spend ~250 on sparks and plugs if I can further narrow down the issue. Granted, I understand that I might have to bite the bullet just to rule it out. On the other hand, I can find a local shop to smoke test it, but does anyone know how much I should expect for shops to charge for such a service?

Thanks in advance.

[brianhinton77]

Originally Posted by mmns999

Thanks for all the replies everyone. I am glad to see that the F25 forum is active.



May I ask, why just a drain and fill and not a flush?
Thanks in advance.

A transmission flush gets hooked up to a machine that evacuates all the trans fluid and it can also clean the build up inside the tranny. The problem is that all that build up can sometimes end up potentially damaging components or block tight passageways. When fluid is forcefully pushed back into the transmission, debris can be dislodged and possibly block narrow channels or one-way valves.

That’s why at 96k, only a drain and fill is recommended. Also, there is a very specific way to do it…if you have ISTA, you can follow the procedure and do the oil balancing in the program. If you dont have ISTA, you can find the DIY here is this forum…..simply put, drain old oil, drop pan, install new pan, fill until oil comes out of fill plug, start car, go through gears, add oil again until it comes out of fill hole, then go driving, …or watch any of the great FCP euro videos on changing fluids, plugs, and coils.

https://x3.xbimmers.com/forums/showt...sfer+box+fluid

[Opie55]

If you just want to read and clear codes, you can download Bimmerlink to your phone. Also, you need something like Bimmerlink to change tranny fluid because the last fill has to be done with the car running and with the tranny fluid temp between 40 and 50 degrees C. Bimmerlink can monitor that, and many other things, live. It only costs about $30. You also need a blue tooth dongle for your OBDII port.

[MSport_Jon]

Originally Posted by mmns999

Thanks for all the replies everyone. I am glad to see that the F25 forum is active.



I have not used a proper scan tool since I don't have access to one as a I just moved to a new area. I am trying to do all the self diagnosis I can before sending in the big guns.



This was always the plan. I have previous service records but the previous owner said that its not complete. I was planning on doing all the fluids in 2k miles as that's when the next oil change is, but that may have to be sooner rather than later. Same with the ignition stuff. May I ask, why just a drain and fill and not a flush?



Funny (or not so funny in my case) enough, I plan to do a visual inspection because when I was first diagnosing this problem, my first thought was to check the air filter since it's easy to do and it could have been a clogged filter or something simple. When I took out the airbox, the damn thing was cracked! The metal ring post MAF sensor was also bent out of shape. Honestly, I have no idea what could have cause such a failure. I replaced the airbox since I thought that the leak was causing the shuddering and obviously because I don't want a bunch of unfiltered air heading towards the intake. But sadly it wasn't. That's why I am planning to do a visual inspection to see if there are any other major crack like that. I agree that a smoke test is the way to go, but would rather do as much as I can before sending it to a mechanic.

To your other point, the problem still persists when in neutral and park. Which I agree indicates is an engine problem rather than transmission. I should have mentioned that in my original post. I admit that I am getting a bit flustered with this, but such is life owning a BMW!



I agree with you and pungo. I have heard of tools such as ISTA and INPA, but have not looked into it much. Is this an expensive investment? If it is, are there any other tools that do, say, 80% of the job? I've read that tools like ISTA require downloading software onto a laptop and has a steep learning curve. This is the first time where I might have to get a scan tool. I own and owned other BMWs before but have never had the need for such advance diagnostics.


In general, would this be as simple as needing new coils and spark plugs? The issue has been persistent for about 2 weeks now and I thought that if it was ignition, it would have thrown a CEL by now. Right? I would rather not spend ~250 on sparks and plugs if I can further narrow down the issue. Granted, I understand that I might have to bite the bullet just to rule it out. On the other hand, I can find a local shop to smoke test it, but does anyone know how much I should expect for shops to charge for such a service?

Thanks in advance.

Sounds like your have a compromised intake. I would definitely correct the issues you mention and clear codes...

Some issues persist even after you correct the issues that caused them. I had a misfire one time and after replacing the failed coil, the car still behaved the same... As soon as I cleared the code the problem went away.

If you want an OBDI tool that is simple to use, go Carly or Bimmerlink. Some of those have 6 dollars monthly subs.

If you want the real deal, go ISTA D/P. This tool is harder but it will do and recover from stations that other tools will not.

[mmns999]

Thanks for all the info everyone.

I am going to look into getting ISTA+ (hopefully I have an old laptop that meets the system requirements) as reading up on it convinced me its the way to go. Though it does look like a huge process to install and learn...

In the meantime, I found a useful YouTube video on how to diagnose the ignition system. Didn't know that the engine could compensate for a faulty ignition that much and also that I could unplug coils as the engine is running without screwing it up... Fingers crossed for that one.

As always, thank you all for your responses thus far. If anyone has any more ideas or further opinions, please feel free to post as they will be welcomed. I check the forums pretty regularly. I will update here if I make headway or if anything changes.

Cheers,
mmns

[mmns999]

UPDATE:
So I changed all 6 coils and plugs today and that seemed to do the trick! As a note for others in the future who may be changing their ignition coils and spark plugs, I just followed this post https://x3.xbimmers.com/forums/showthread.php?t=1131028.

And because there is a lot of misinformation out there: no, the N52 engine does not need a thin walled sparkplug socket, I just used the normal spark plug socket in my toolbox.

The plugs looked fairly worn when I pulled them out, but nothing too crazy. However, one of the ignition coils had what looked to be the internal spring that was busted and was preventing contact with the sparkplug. I have no idea what would cause that, but what I do know if that my car no longer has the weird shudder!

Thanks everyone for your inputs. Goes to show that sometimes it is just the simple answer.