There have been no real problems with this car recently other than having the ignition replaced. But over the last two days, it has been dying randomly as I drive it. It happens when I'm stopped at lights and also while driving, though usually when I start to slow down. It doesn't sputter or give any indication that it is going to go out then it just stalls. A few times the car drops off, there's no power and the rpms shoot to zero and it will slow down, but it doesn't stall. If I press the gas, usually it kicks back on. Does anybody have any idea what might be the cause? Thanks.

I also forgot to mention that it starts up fine after it stalls. I usually just put it in neutral and restart it and go. Thanks again.

Tonight the car has decided to just not start up any more. After doing some research, I'm wondering if maybe it is the fuel filter or maybe the fuel pump. Could it possibly be due to the fact that it is in need of a tune-up? I'm thinking it has something to do with the fuel though. Hope someone out there has an idea. Thanks.

I HAVE A SIMILAR PROBLEM. My 1988 760 with the B230F/T engine will occasionally stall when I come to a stop. sometimes it starts right back up - others you have to wait for a minute at most - I never actually timed it, it may be less. It will also show intermittent quick drops in RPM (just a few sparks dropped) or a more lasting drop in RPM (to zero with corresponding feeling I downshifted - but it's AUTOMATIC) and it has always recoverd from that without me having to go to neutral and restart - so far.

Here is what I found:

The one time it failed "on command" I was not getting the "fire" impulse to my coil. This impulse starts in the distributor (A "Hall Sensor"?), goes to the ECU (behind vanity panel near driver's left foot) then out to the power stage (a solid state amp found under the hood near the battery and the ignition ballast resistors on the left fender) so I'm pretty sure the cause is one of those three items. The ignition key signal was rock solid to the coil and the one time the failure happened while we had a meter on and connected there we saw that the impulse from the sensor was either not being produced or was not making it through the ECU and amp because it was not visible at the coil. You can see this firing impulse with a properly connected simple, cheap, test light. Here's how - connect one side of the test light to ground (or battery negative) and the other to the post where the discharge signal comes into the coil from the power amp. Turn the key to the "ON" position without going to "START". The test light should be on and steady or you've got an ignition wiring problem that is keeping your 12 VDC from the key from making it to the coil. Whenever you push the key to START and crank the engine the light should flicker off then back on with each spark impulse from the Hall sensor through the ECU and amp to the coil.

I found other problems in my car that were probably unrelated - loose/leaking vacuum lines (2), a bad spark plug wire (#1 came apart in my hand), a dirty butterfly valve (but not sticking) in the throttle body and my timing was off by a bit. At one point my idle went crazy - it was running over 1000 when it was supposed to be about 700-750 or so. That problem disappeared as mysteriously as it began though. I also found a potential wiring problem - going into the wiring under the dash to get at the ECU causes my unlock solenoids to trigger so I've got some sort of intermittent open or short (have to research it) there. It could well be related to my stalling problem if the lock solenoid wire is somehow contacting one of my ECU wires I suppose - or not.

The insulation on one of the leads to the Hall sensor didn't look like it needed a repair - I think that is the first thing I will try before I buy the sensor itself as it could well be the reason my signal is intermittently bad.

Always go for the known problems before you look for unknowns...

And if you have to start from scratch, remember, eliminate problems with air, fuel and spark one by one.

OH, one question - when you say "having the ignition replaced", what do you mean? The actual cylinder that you put the key in to start the car? Or some other ignition system parts?

My key stopped working some time ago. I replaced the cylinder but I do not believe this is related to the new problem - at least as far as I recall it cropped up significantly later.

It has been a while since I have been on here, but I have done a few things since my initial post. I replaced the Fuel Pump Relay, checked the radio suppression relay (which looked fine), and replaced the rpm (crank position) sensor (which has a cut half-way around with the wires inside exposed). After all this my car now will not run for very long once I turn it on unless I hold my foot on the gas. It seems like a fuel problem. I went to replace the fuel filter and that is what has brought me back to the forum. It was trickier than fuel filter replacements on other cars, and I'm afraid I may have done something wrong. When trying to remove the bolts connecting the filter to the hose that goes to the pump, we got a little movement, but I can't tell if that was movement from the bolts or something breaking. Right now I have a bucket with about 3 cups worth of fuel in it and it is still slowly dripping. I probably should put this as a new topic, but if anyone out there has a suggestion, I would save me a lot of stress. One of these days this car will run again! Thanks.

my 740GL was doing the same thing. stalling when slowing down and finally not restarting. turned out to be the distributor cap and rotor. both parts totalling $40. takes about 30 minutes to replace both. hope that helps.

Actually mine just did that last week, Turned out my alternator went poof. Put in a new one and she is good as gold.

wwdragon

When I bought my 92' 740 turbo wagon a few years ago.. it worked fine when I tried it... then I got home.. and a day later it started dieing in idle...

I'd start it up, leave home, drive about a mile or two, then stop at a light, and it'd die... turn it back on and it'd die if I didn't push the accelerator soon enough...

I took it to my mechanic and he found that the fuzzy stuff... I guess it was like a secondary filter or something at one point... that is under the air filter deteriourated and got sucked into the pipes or what not... and it plugged it up... and got burned onto a sensor that like senses air flow and uses it to set idle speed.

Man... the car sudenly had more oomph overall when that was dealt with.