What the hell just happened?

[cawimmer430]

So yesterday I drove up to Hannover to shoot a rare car. Hannover is about 660 km away and it's a roughly five hour drive up.

The shoot finishes at 9:30 PM and then I am on my way home. I don't want to spend the night in Hannover and if I speed all the way down I can make it to Munich at around 2 AM.

Anyway, I am speeding down on the Autobahns at 200 km/h+ when suddenly the check engine light comes on and I my engine loses power. I manage to keep the engine running by downshifting on the A/T. I keep the car stable at 110 km/h in 4th gear - very loud. If I shift into 5th gear to decrease RPM and noise the engine stutters, vibrates and feels like it's about to die. And I am slowing down. So I need to keep it in high RPM at a lower gear.

At this point it's a little past 10 PM on a Saturday night. I have no desire to pull over for fear that the engine won't restart. At this point I am roughly 550 km away from Munich and I am taking the former East Germany route down (Berlin-Dresden-Lepizig...). My first thought was a faulty ignition coil (hasn't happened in ages) because the engine was running rough and vibrating, but the more I become familiar with the situation it seems, and this is just a guess - that perhaps one of the injectors was clogged! So my car was running on 3-cylinders instead of 4-cylinders. Accelerating is a pain. When I am behind a truck my acceleration is so slow, even in low gear, that I have to stay behind them at 80 km/h in 3rd gear - because 4th gear causes the engine to stutter and vibrate. Ugh, this is loud.

Naturally my forced low gear/high-RPM driving is consuming my fuel reserves. I have a range of about 200 km, but lower due to the situation. I pass several gas stations but I do not want pull in for fear of the engine not restarting. My plan was to limp out of East Germany with my remaining fuel reserves and at least break down in Bavaria!

Here's the killer. I proceed to drive like this for roughly 100 km when suddenly the check engine light goes away and I have full power back.. At first I am a little skeptical, carefully adding power, changing gears to see if the engine can handle it. NO PROBLEMS.

First thing I do is pull into a gas station to fill up just in case this happens again so I have more range. Engine starts - without problems. No check engine light comes on. At this point I am just blasting down on the Autobahns at top speed, wanting to get home ASAP and "break down" in Bavaria/Munich if this were to happen again. 


Do you guys know what was wrong? I am no engineer but I have this gut feeling that it was a clogged injector. If the ignition coil were faulty I don't think the problem would have resolved itself. This morning I started up the car and took it for a test spin around my area. Everything works fine. Still, I'm glad the season is coming to an end because after this experience I'm a bit wary of taking her on longer journeys. I don't want to spend any money at the BMW dealer buying a new injector or whatever was problematic. Let the second owner deal with that issue!

[mzziaz]

Strange. It is a manual, right? I'd start by pulling some codes.

[cawimmer430]

Strange. It is a manual, right? I'd start by pulling some codes.

Nope, 6-Speed Automatic but with manual control (I can select all six gear individually).

Car works fine now but I don't feel like bringing it to the BMW dealer and wasting money on "fixing the problem" (if there is one). If I were keeping the car then I'd get it inspected. But since the car is going away in November I just hope it will work normally until then - then the next owner in Eastern Europe or North Africa etc. can deal with the issue if it pops up again. Man, I am evil. 

[mzziaz]

Lets hope the A/T doesn't crap out before you get rid of it.

[MX793]

I'd wager it was a coil.  Same as losing a fuel injector in terms of the engine not running on all cylinders.  Does the exhaust smell like raw gasoline?

[dazzleman]

The weird thing is that the issue resolved itself, apparently.  I would still get it checked before taking any more long drives.

[FoMoJo]

If it lost a cylinder it would pretty much have to be either a coil pack or an injector; unless a plug just got temporarily fouled.  At least get it checked.

[Soup DeVille]

Another possibility is you lost a wheel speed sensor for a bit. Some GMs have been known to cut power because of the loss of a wheel speed or steering angle sensor.

But yes, you need to start by pulling the code.

[CaminoRacer]

Yes, pull the codes

[AutobahnSHO]

I had that happen in my SHO when I first bought it. Turns out one of the plug wires was not connected all the way.

A year or so later, started doing it again. Would drive fine for a week then act up for a few minutes then drive fine. Crankshaft sensor was bad. Codes revealed that problem!!
ALSO, that's when I joined CarandDriver looking for help in the garage, someone there pointed me to the SHO forum, they knew the answer right away. Check with other BMW enthusiasts too?

BTW a bluetooth code reader is ~$20US and you can use it with any modern smartphone. I like the Torque app.

[cawimmer430]

I'd wager it was a coil.  Same as losing a fuel injector in terms of the engine not running on all cylinders.  Does the exhaust smell like raw gasoline?

The exhaust smells normally [when the engine has reached its operating temperature].

The engine also sounds normal.

Drove the car again today including on the Autobahn. Everything worked fine. No hint of power loss etc.

[cawimmer430]

Thank you all for the replies!


I phoned my dad this morning asking him if I could borrow his E-Class for longer drives. He's cool with it and even suggested I should use the 500SL for daily driving - I'm cool with that. The SL can be driven until October (albeit with summer tires...) and then in November I could borrow his E-Class and give him the 1er to use in the province. He won't be driving much anyway except to the supermarket so short trips. Seems like the perfect arrangement.

Luckily most of my upcoming projects are in and around Munich, so if I should break down it's not a big deal. I can visit a BMW dealer and have the codes read, but I just don't want to pay for any major problem that they might discover.

[Soup DeVille]

Thank you all for the replies!


I phoned my dad this morning asking him if I could borrow his E-Class for longer drives. He's cool with it and even suggested I should use the 500SL for daily driving - I'm cool with that. The SL can be driven until October (albeit with summer tires...) and then in November I could borrow his E-Class and give him the 1er to use in the province. He won't be driving much anyway except to the supermarket so short trips. Seems like the perfect arrangement.

Luckily most of my upcoming projects are in and around Munich, so if I should break down it's not a big deal. I can visit a BMW dealer and have the codes read, but I just don't want to pay for any major problem that they might discover.

They wouldn't make you pay for more than the diagnostic, unless the car is unsafe.

[cawimmer430]

They wouldn't make you pay for more than the diagnostic, unless the car is unsafe.

Currently the car "runs fine", so for local driving I think I can risk it. For longer journeys I will borrow the E350 CGI or 500SL.

And then in November I'll have a new ride so whatever happens to the BMW is of no more concern to me. Gosh, I sound so evil and careless now.

[MexicoCityM3]

Coil/plug/injector. Your new car isn't coming until November, right? I'd get it fixed man, it's a safety issue. Doesn't sound too expensive. Don't be cheap.

[Soup DeVille]

Currently the car "runs fine", so for local driving I think I can risk it. For longer journeys I will borrow the E350 CGI or 500SL.

And then in November I'll have a new ride so whatever happens to the BMW is of no more concern to me. Gosh, I sound so evil and careless now.

All I'm saying is that its no trouble to get the code read. In the US any parts store will do it for free; some codes can only be read compeey by the dealer,  but most will turn up with a generic scanner.

[shp4man]

Just saw this thread. Sounds to me like the ETB (electronic throttle body) has an intermittent fault. Typically, if you pull over and cycle the ignition it will clear. It's a safety feature, one little glitch will set failure effects management, which prevents throttle opening. Can't have any accidents or lawsuits. 

[cawimmer430]

Coil/plug/injector. Your new car isn't coming until November, right? I'd get it fixed man, it's a safety issue. Doesn't sound too expensive. Don't be cheap.

Yeah, first or second week of November according to MB.

I have a few more projects coming up, but they are all local. In October there might be something in Stuttgart and I think I will just borrow my dad's E350 CGI/500SL.

For now the BMW is acting ok. I have a friend with a classic car shop who also works on modern cars. He has a code reader which works on newer cars. I may pay him a visit instead of BMW - for now.

[cawimmer430]

All I'm saying is that its no trouble to get the code read. In the US any parts store will do it for free; some codes can only be read compeey by the dealer,  but most will turn up with a generic scanner.

A friend of mine has a classic car dealership and his shop also works on modern cars. His code readers detected the broken thermostat on my BMW. I am sure it will find the potential problem in this case.

[cawimmer430]

Just saw this thread. Sounds to me like the ETB (electronic throttle body) has an intermittent fault. Typically, if you pull over and cycle the ignition it will clear. It's a safety feature, one little glitch will set failure effects management, which prevents throttle opening. Can't have any accidents or lawsuits. 

Ah, I am not an engineer so I would never have thought about this. But on the 1-Series' gasoline 4-cylinder models injector and ignition coil failures are the most common problems. I've not had them in years, but that was my first thought when the check engine light came on and I lost power - and it felt like I was cruising on 3 instead of 4-cylinders.