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-   -   Shudder or misfire after kicking up some water. Thoughts? (http://www.bimmerfest.com/forums/showthread.php?t=661097)

gnucar 11-28-2012 09:17 PM

Shudder or misfire after kicking up some water. Thoughts?
 
X5 4.8is 2006 model

Starts fine. Idles fine. When gently accelerating it intermittently 'shudders', which I attribute to a misfire. I feel this in the gas pedal, but the RPM gauge is as solid as a rock. It 'sometimes' has a very high propensity for doing this while holding the speed around 30 Mph or gently accelerating from that speed, enough that it makes me cringe worried about damage to the engine. When sometimes running smoother, it will have good power (even when pushed, it does just fine) and runs well....but when coming to a stop, it will shudder just before coming to a full stop (but after the last shift down.). It ALWAYS idles perfectly.

If it is in park and I slowly rev it up to 2.5k RPM, slowly bring it back to idle, or do anything in between, it runs perfectly. It's almost like it does it more under load, regardless of RPM. ...though parking in a parking garage (twice) it runs perfectly, even after shuddering all the way to it.

No error codes. No pending error codes, it's like it thinks it's a normal day.


Background:

It's run perfectly since buying it a year ago, and is generally in great condition. Yesterday I ran through about 4 inches of water (max) at 30 Mph or so, thinking it was much less deep. At 15-25 Mph, I hit more water about 1-2 inches deep or so. Apparently this was the first time I have hit puddles of that depth in this vehicle, as the amount of water thrown up surprised me....far higher than the X5 and massive amounts. Minutes after that, I noticed this happening for the rest of the 20 minutes home, rarely getting above 30 Mph during the drive.

Today I drove it 150 miles because I had to...it seemed better than last night (which was extreme), but behaved how I described above. At highway speed it seems fine but I may just not be noticing because of the higher RPM. On city streets you really notice it. Just before getting home, on a long stretch of 30 Mph, it seemed about as bad as yesterday. ...just after that, I go up a parking garage and it runs great.

Sorry for being long winded, but I wanted to be complete. Any ideas would be GREATLY appreciated...I've got an appt with the dealer for next week and am bracing for the $$.

Lastly, if I am on the brake when it shudders I do not feel it in the brake pedal. On a long shot I turned off DSC in case it went nuts but not luck, no change.

Thanks!

gnucar 11-30-2012 11:43 AM

Update

Due to the RPM's staying solid I began to suspect the trans shifting out and in gear quickly, so I switched to manual mode, but there was no change.

It always idles perfectly in drive (at a full stop) or in park. It also revs perfectly in park, as well as in drive when at a full stop and holding the brake and revving just a little (but not moving).

I have also watched the RPM's very closely and have caught it doing it when changing gears and the RPM's are dropping quickly (as normal)...and it drops perfectly smoothly so I am getting some hope that it may not be the engine unless the RPM gauge is just showing an 'average' rather than a live reading.

This all has made me start wondering if it could be something with the traction control as it feels and sounds a lot like the hill descent does, and only happens when it is moving. The sudden 'loss of power' and shudder made me suspect misfiring before but a quick tap to the brake on one wheel could feel similar.

...but then that makes me wonder what could do that without registering an error?

Thanks!

gnucar 12-10-2012 02:02 PM

Ok, got it back from the dealer today. Had oil and tires while it was in because it was time. They said that it is a worn gear in the transfer case and is ok to drive but will get progressively worse until failure. ...and quoted a price of $3,600 to replace it.

So, the only questions remaining... Does this sound realistic? Could losing traction in a few big puddles have caused extra stress that pushed a fragile gear over the edge...because otherwise this is a heck of a coincidence. And, how ridiculous is the price? I know it's high, it's a dealer, but is it laugh out the door high or 'just pay it' high?

Thanks!

petriej 12-11-2012 08:52 AM

That's pretty steep. Try to find a transmission shop and get another quote.

Graham132white 12-11-2012 09:06 AM

Doesn't sound like transmission failure to me. I had exactly the same issue to the letter on my x5. You need to look at what your live data is saying for the fuel trims at idle and revving at 2k ish.
Without load mine revved perfect and Idle was perfect. Under load it would do exactly the same as you describe word for word. I had no codes at all, I assumed vac leak or faulty MAF. Finally yesterday after several major strips and investigations I had a code pop up, low maf circuit reading. I had never had this before while having this problem for months. Fuel trims were well out, replaced the maf for a new Bosch one and bingo, car is like new and goes like a train with no faults at all...

I had all the shudders and coming to a stop was identical to your issues, it really did feel like the transmission was struggling as you described.

Graham132white 12-11-2012 09:10 AM

Unplug your MAF temporarily and see if the problems go away, if they do then bonus, buy a maf.

gnucar 12-13-2012 04:32 PM

Having researched MAF problems after your reply, it gives me hope that this could be the cause. It is running an oiled air filter. It had it when I got it and I figured it was a nice little upgrade....but reading about MAF sensors it seems to be a main cause for problems. So, I got an OEM filter and will see how it does (it has improved, which would be odd if it was the transfer case). I will also try (carefully) cleaning the MAF and will report back with results so hopefully this journey may help someone else later.

Thanks for your thoughts, you may have saved me some serious $$.

Graham132white 12-14-2012 03:22 AM

Cotton wool buds very gently on the element with carb cleaner. You'll see how much crap is on the end of them. I did this which partially fixed the faults but within weeks had to buy a new MAF as they are never as good when cleaned. A new one at only 70 in UK for Bosch made it like a rocket ship!

Buzz110 01-18-2013 11:00 AM

They now make a MAF cleaner that works well, you can purchase it at mostly any auto supply house. Do not use the carb cleaner as it is too strong and will damage the sensor. Additionally stay away from the part of the sensor that has a gel like substance on.


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