Oh know it won't start!!!!!

Please help, my 1999 740i just died at a light. There is no power at all as far as the ignition goes. Its like trying to start a car with no battery in it. However, the battery is good, interior lights work electric trunk etc..... I put the key in the ignition and i get nothing,, no radio, no display, no crank no start. The alternator and battery are fine, and all fuses are good.. So what now??? I don't want to bring it to BMW.:banghead:

Try disconnecting the battery for about 10-20 seconds...make sure you know your radio code before you do this else your engine won't be the only thing not working.

For more info on what disconnecting the battery will do, see Magic Reset (http://www.automotiveforums.com/vbulletin/showpost.php?p=4666653&postcount=1)...it just might fix it and might even be the cheapest and simplest fix you have ever done.

If that doesn't immediately fix it, it might be ignition relays, but I'm not sure myself as I have an E32. I'll see what if I can find something for ya to help ya out!

Try disconnecting the battery for about 10-20 seconds...make sure you know your radio code before you do this else your engine won't be the only thing not working.

For more info on what disconnecting the battery will do, see Magic Reset (http://www.automotiveforums.com/vbulletin/showpost.php?p=4666653&postcount=1)...it just might fix it and might even be the cheapest and simplest fix you have ever done.

If that doesn't immediately fix it, it might be ignition relays, but I'm not sure myself as I have an E32. I'll see what if I can find something for ya to help ya out!


Thanks for the info. I tried it but I think its beyond that. I'm going to get it towed to the dealer today i'll let you know what it was.

hi, im new to this site but desperate for help and ive read some of your replys and it sounds like your the man who knows ! please try and get your brains round this lot please please . bmw 740i v8 , parked up for 2 years , charged battery ,kept jump leads on from running car as well .fresh fuel , took out all spark plugs , all sparking , fuel coming thru , plugs back in , still not starting, previous owner had tried using easy start aerosol up air intake pipe , would this affect maf , if so can it be "cleaned". getting spark ,getting fuel , not sure about air ? ......would engine still crank over if immobiliser was still on ????..... would magic reset work like you described in one of your posts. ....... hellllllllllpppppp im stumped on this , please explain in simple terms without getting to techy please . thanks dave ,uk

The magic reset could possibly help. That is why it's called a magic reset. ;) :D

Will the car still turn over when the immobilizer is active? It will and it might. It depends on what year 740 you have (tis essential to list year and model).

If it's an E32 740i (in other words, if your 740i was built between 92-94), then the car will still crank if the immobilizer is active but will not start. I've had this happen on my car a few times and I kind of got scared that there was something deeper. On E38's (95-2001/2), I am not certain.

MAF's don't usually go bad. So it might be a little dirty, in which case it is possible to clean them. If you have cleaned them and it still isn't starting, disconnect the MAF's and reconnect. This might re-establish a solid connection to the MAF's. The only reason for a bad MAF is if you don't have an air filter installed and a large particle were to hit the MAF and take out the hot wire (the wire that measures the air flow into the engine so it can regulate a proper Air/Fuel ratio). If the hot wires are still in tact, then you might be looking at electrical connections themselves. The voltage required to power the MAF's properly may not bet getting to the MAF's. It is possible to test the wires while the harness is still connected.

Here are a few links for you to read. I appologize if they are a bit too technical, but I might help you.

MAF Testing (http://www.bimmerboard.com/forums/posts/131522)
MAF Cleaning (http://www.louv.tv/cars/m5/MAF/) - This is for a 2000 M5 but the principle remains the same. If you wanted to do an easier cleaning method that I've heard works, get some carb cleaner and spray in the intake after the air filter. This is safer as it is a petrolium product.

If none of these work, you might be able to borrow (as your car won't start) a code reader from autozone (if you live in the United States) and pull the diagnostic codes (they will do it for free if you were able to take it into them). Or if you wanted to, you may puchase your own from Peake.

http://www.r5tool.com/code_tool.htm - read this entire page through to understand what accessories you may need to communicate with your car to successfuly pull these codes.

If none of these things work to correct your problem, you might be looking at a cam shaft position sensor...which I won't get into right now cuz I'll have to think of a way to explain that simply, and why get into it right now until you try those above...they might work! :D

Good luck!