2006 750 Li suddenly consuming lots of gasoline

Hi Guys,

My 2006 750 Li suddenly started consuming lots of gasoline (I'm going by the gauge only, haven't re-fueled yet). The range drops by 1 mile every few seconds, and after driving it only 30-40 miles, the range dropped by about 160 miles (not sure what this works out to, but maybe 4-5 mpg)!

Needless to say, this is pretty alarming. But when I took it to the dealership, they stated that the computer isn't showing any error codes and everything looks okay. They don't seem willing to investigate the issue any further, and I'm not sure what to ask them. I asked them if anyone had actually tried driving the car, and they were evasive and kept claiming that if the computer doesn't have an error code, everything is okay.

Has anyone experienced similar issues? Is it safe to keep driving the car? I don't notice any difference in handling or power. There might be a slight hesitation, but its very hard for me to tell.

Thanks for your advice,
Jake

The range is based on the last 20 minutes of driving. If you we're on the highway getting 25mpg and the started driving around town, the range could certainly drop that quickly.

At 25mpg, a full tank would take you 500 miles. Say you drive through half a tank; the range will read 250 miles to go. But, at 13mpg, a half-tank will only get you 130 miles. That would drop the range 120 miles plus whatever you drove in those twenty minutes.

You should monitor the average economy per tank of fuel. If your average economy takes a dive, that will tell you if there's actually a problem.

I'd check to see if your EGR valve is filled with crap. That and maybe your O2 sensors are on their way out...both of those will effect gas mileage.

Hi guys,

Thanks for your comments.

I just wanted to update you on what happened. It seems like the root cause of my problems was a low battery. It's a fairly new Sears Diehard, and the tech who installs it is sure he registered it, so I'm not sure what's up. Anyway, after putting it on the trickle charger, the range indicated started behaving more normally, and the next time I gassed up the car, I calculated my MPG at 18, which seems totally normal for this car. In other words, it wasn't the car burning gas, but the low battery was causing the sensors to go wonkers.

For now I'll keep the car on the trickle charger every night, but going forward, I'll have to figure out if the battery is bad, or the car is not charging it properly (e.g. due to a bad registration). I'll keep this thread updated.

Originally Posted by jake_the_snake

Hi guys,

Thanks for your comments.

I just wanted to update you on what happened. It seems like the root cause of my problems was a low battery. It's a fairly new Sears Diehard, and the tech who installs it is sure he registered it, so I'm not sure what's up. Anyway, after putting it on the trickle charger, the range indicated started behaving more normally, and the next time I gassed up the car, I calculated my MPG at 18, which seems totally normal for this car. In other words, it wasn't the car burning gas, but the low battery was causing the sensors to go wonkers.

For now I'll keep the car on the trickle charger every night, but going forward, I'll have to figure out if the battery is bad, or the car is not charging it properly (e.g. due to a bad registration). I'll keep this thread updated.

-amin

Did you install a regular battery or did you install an AGM battery? If your battery is not an AGM battery that could be your issue.

> Did you install a regular battery or did you install an AGM battery? If your battery is not an AGM battery that could be your issue.

Sorry for the delayed response, it took me a long time to research this. The battery is an AGM, a Sears Diehard to be specific, and the dealership told me it was appropriate for the car (this is a different dealership than where it was installed). On the other hand, there seemed to be some problem with its registration. They're going to re-register it, let's hope the issues disappear.

But, the dealership also told me I have engine oil leaking and need to replace upper timing cover gaskets and valve cover gaskets, for which the dealership is asking $2400. In addition, there's a torn or failed seal inside the transmission (mechtronix sleeve or something), and I've been quoted $900 for that.

At the moment, I'm a little disappointed with the build quality of this car. It's been very well maintained, and yet it's having all these problems with only 75k on the odometer. Not sure what to think about BMW's engineering.

Originally Posted by jake_the_snake

> Did you install a regular battery or did you install an AGM battery? If your battery is not an AGM battery that could be your issue.

Sorry for the delayed response, it took me a long time to research this. The battery is an AGM, a Sears Diehard to be specific, and the dealership told me it was appropriate for the car (this is a different dealership than where it was installed). On the other hand, there seemed to be some problem with its registration. They're going to re-register it, let's hope the issues disappear.

But, the dealership also told me I have engine oil leaking and need to replace upper timing cover gaskets and valve cover gaskets, for which the dealership is asking $2400. In addition, there's a torn or failed seal inside the transmission (mechtronix sleeve or something), and I've been quoted $900 for that.

At the moment, I'm a little disappointed with the build quality of this car. It's been very well maintained, and yet it's having all these problems with only 75k on the odometer. Not sure what to think about BMW's engineering.

Go to a Indy. Timing cover an valve cover gasket should only cost you around $500.00 parts an labor. As for the mechtronic sleeve that's only a $23.00 part an while you there go ahead an replace the adapter which is only $23.00 also. Replace the pan an filter all that should cost you less than $700.00. I would say Look around spending a total of $1200-$1500.00 depending on who you use.

Originally Posted by Rookie2008

Go to a Indy. Timing cover an valve cover gasket should only cost you around $500.00 parts an labor. As for the mechtronic sleeve that's only a $23.00 part an while you there go ahead an replace the adapter which is only $23.00 also. Replace the pan an filter all that should cost you less than $700.00. I would say Look around spending a total of $1200-$1500.00 depending on who you use.

I have the same two issues on my 06 750 who do you know in LA can get my baby from leaking valve seals good price

I used a mobile tech when I did mines. You can ask around on the forums, there were a few guys here who did this also for $500.00 at a shop. I know a good Mater tech here in the valley but he will charge 495 a side If I remember correctly.