Problem with X5
 

For the last month or two, ever since the weather turned cooler, I have been having problems getting my 2008 X5 3.0si to start in the mornings. The battery is new and cranks perfectly but the engine just won't turn over. Sometimes it takes 6 or 7 tries, with a full minute of cranking, before it starts. I have taken it to the dealer twice but they can find no problems. In warmer weather, or in the afternoon, it usually starts on the first or second try, which is perhaps why they can find nothing wrong. But for years, this X5 started perfectly, first try, every time. The car is currently at the dealer and will stay for another week in the hope they can find the problem. Any ideas?

Thanks!

Pet Peeve: if the motor is cranking- ie "rotating" then it IS "turning over".

You mean it wont START.

Oh...I'd look at fuel pressures and maybe just replace the fuel filter prophylactically...maybe over the last 5 years the fuel flow has dropped a bit to now cause cold start issues.

Dealers are generally idiots who only look for codes and testplans these days. Yes, there are a few very good diagnosticians, but the odds that they will put one of those valuable guys on your little issue are low.

IMO

A

There was a thread on here earlier in the week addressing a similar issue. One suggestion was to change the plugs. I'm having a similar problem although not nearly as severe. I've ordered some and I'll let you know if it helps...

You say that the battery is new ... while it may be new, that does not mean that it is charged to the appropriate capacity to handle the complete load the car demands during startup.

Cranking power (CCA) of a battery is only one indication of the condition of a battery. That's why it can turn the starter motor. But, it also has to have sufficient reserve capacity to fire up all of the other electronics involved in starting the car. The reserve capacity of a battery is closely related to the Amp-Hour rating of your battery.

This is where things get interesting: if your battery is (recently) new and you or your dealer never registered and programmed the car's computer to recognize the new battery, then there is a good chance that you are either undercharging or overcharging the "new" battery. As your old battery ages, the intelligent battery monitor tells the alternator to put out more current. When you replace the old with new, the same amount of current will be pumped into the new battery. Either too much or too little is bad for the battery (over time). The end result is that you never charge the battery to its proper capacity and hence you end up with hard starting symptoms like you have now. The fact that you need to crank it 6 or 7 times is a good indicator that the battery is not at it's full capacity. Take the car back to the dealer and have them:
1. check the rating on your (new) battery
2. make sure the battery is properly registered
3. double check to make sure that the car is programmed for the proper Amp-Hour (Ah) rating of your battery.

BTW, doing this through the dealer can be very expensive!

Then, buy a Battery Tender and hook it up to the car on nights that it gets cold (40 deg or below) or if it is parked for more than 48 hrs.

Could be the crankshaft position sensor. My 07 4.8 had similar issues. Then, finally, I walked out from work one day to go home and it would turn over but never start. Then, I tried again and I got a transmission failure message. So, I called a tow truck and when the truck got to my office, I tried starting it one more time and it started up without any errors. I drove it right up on the flatbed and turned it off. Dealer replaced the crankshaft position sensor under warranty and it's been good ever since.

Interesting. I'd sat this has nothing to do with the OPs issue.... if you think it does, describe how this would impact STARTING (not CRANKING!!!!) and only when cold. Somehow the improper battery stuff you cite is impacting fuel or ignition...(yet it has plenty of juice to run the high current starter motor)..HOW?

HOW? Glad you asked ... it helps to be informed ... read pp 5 - 20 in the attached, especially p. 7 and p. 18

Yeah, I have that too.

I know you are excited about discovering about coding for your own battery...:thumbup:

but again, nothing in that document describes how your theory fits the OPs symptoms... plenty of cranking voltage, but issues with start (ignition or fuel)

(This theory that improper registration will lead to hard starts in cold weather is, well, lets say 'as yet unsupported'.)

And 100% agree it helps to be informed. :)

A


PS 99% of that document describes things that happen AFTER the car is RUNNING.

Agreed with you. Don't see how it related to OP problems. Beyond me, very confusing post.