Coming as no surprise to anyone, including me, my 2008 BMW 760Li failed miserably during its first road trip. After giving a short glimpse of its greatness, the dashboard treated me to its own version of a Christmas tree lighting ceremony followed by the single worst invention ever from BMW — “limp home mode.” This situation left me 400 miles from home in a giant sedan with the approximate horsepower of a John Deere riding lawnmower.
To recap my V12 BMW ownership before this incident, I bought my 760Li at auction for only $4,500 after it was traded into a Volkswagen dealer — and promptly spent another $3,000 for my mechanic to tear the engine apart to address numerous leaks, fix the sputtering engine and catch up on lots of deferred maintenance. Considering the low cost of entry and the fact that my BMW had more than 150,000 miles on the odometer, this was to be expected. Still, I deluded myself into thinking that I would have some reliability after this first round of repairs because I thought I had purchased one of the good BMWs.
As far as engineering snafus go, BMW is known for its numerous mistakes. Some of the more famous examples include failing Nikasil cylinder liners in the mid-’90s and rampant timing chain guide failures around the new millennium, and the 2000s brought a slew of problems, such as weak valve stem seals and rod bearings and rampant variable valve timing problems. Those are just the engine issues I can think of off the top of my head, but truly, someone could write a 1,000-page novel with the rest. Fortunately, though, in the 30 years that the BMW V12 engine has existed, it’s managed to avoid any serious mechanical defects. Unfortunately, though, the BMW V12 also birthed one of the worst electronic inventions ever to the human race, and that’s “limp home mode.”
When the first BMW V12 was being developed in the 1980s, BMW chose to treat each bank of cylinders as its own separate engine. Each side was given its own engine computer, intake, throttle body and fuel delivery system, and to get these conjoined twins to work together, BMW introduced the first electronic throttle control system. Instead of having a physical cable connected to the accelerator pedal and the throttle body, BMW unveiled a fly-by-wire system that electronically detects throttle inputs from the accelerator pedal and sends a signal to a servo motor that opens up the throttle body. In the case of the V12, that’s two throttle bodies, which doubles the complication.
Owners of this first generation of BMW V12 engines are likely well aware of the dreaded EML warning light (EML is an acronym for the German translation of electronic throttle control) that indicates that the throttle system has gone into a fail-safe, or “limp home,” mode. This means that something has gone wrong with the system, be it a sticking throttle body or a bad sensor, and, for safety purposes, the computer greatly reduces engine power and throttle response. This results in misery for the unfortunate owner and what I consider to be dangerously slow acceleration. This system has since been widely adopted by every other automaker — and while BMW was the first, it seems they still struggle with keeping this system working properly.
This brings me to my work trip last week to rural Arkansas, much of which was through curvy state highways that car enthusiasts love. I wanted to take something that was comfortable but also fun enough to tackle the twisties, and I thought that my freshly sorted 760Li was the perfect choice. For the first 400 miles, I was very happy with my decision, as the seats in the 7 Series are extremely comfortable and its active suspension and 438 horsepower ate up the two-lane rural Arkansas highways. Not long after I arrived after my destination, though, my BMW decided that it had enough fun — and began lighting up warning lights accompanied by BMW’s pleasant chimes of death. I then noticed that the engine wanted nothing to do with the desires of my right foot.
While I wasn’t stranded and I was able to get around town with lawnmower power, the trip home would be miserable. An engine scanner purchased at Walmart produced numerous codes for throttle position sensors and misfires — which meant that it wasn’t going to be an easy fix. This meant I had to drive my BMW back 400 miles home in fail-safe mode, and I wasn’t happy. While it would eventually accelerate to highway speeds at a rate of about 1 mile to 60 mph, any kind of passing maneuver was impossible. Most of the time, I was the one being passed by angry motorists.
My new BMW mechanic was very distraught by the news, and he suspects a wiring issue or a failed computer. But this whole experience left me wondering why BMW would program a car with such a dangerously slow fail-safe mode in the first place. I get that it wants to prevent any unintended acceleration when something fails, but other automakers have engineered more reliable systems, and the fail-safe modes that I’ve experienced firsthand with Mercedes, for example, are far less debilitating.
I’m not ready to give up on this 760Li yet, and buying any broken auction car like this often involves peeling through an onion of issues, but we’re not off to a very good start. When it’s working, though, the silent, effortless torque of the V12 accelerates with the same satisfying feeling of an electric car, and the ride and interior comfort are fantastic. For this reason, I’m willing to give this BMW a few more chances before I start digging another hole. Find a BMW 7 Series for sale
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