1994 940 Sedan
Automatic
265k (rebuilt engine at 192k)
Non-turbo

I bought this car about 2 months ago. All was good with it until last weekend. I went to move it and it didn't feel like starting. It took about 45 seconds of key in ignition torture to get the thing to start. Everything sounded fine except it just wasn't planning on starting until I pushed the issue. The next few start ups were also slow, then got better. However, the long start up time comes back every now and again. I had the ignition system tested and the problem doesn't seem to be there. Battery, starter, alternator, ignition coils, all good.

Well, maybe I could let that go. I mean it does start even if I have to beat it. However, this problem was accompanied by another, sudden rough idle. Driving it is fine. When I stop though, it sounds like it suddenly wants to kill itself. It will occasionally stumble badly upon acceleration out of a stop. My tach has its own problems (sometimes it reads nothing when the car is idling obviously on, or is off by a few hundred), but when it does want to read, it tells me that it is idling at about 500-600, drops to nearly 100, sounds like it will stall, then shakes out of it back to about 700. Fine for a few seconds to a few minutes. Rinse, lather, repeat. The car is fine once it is going though.

Engine temperature has little to do with it. It will idle rough cold or hot. Gas mileage is unaffected by this. On occasion though, there is the overwhelming smell of gasoline coming from the exhaust. The color and amount of fumes though is otherwise unremarkable. The fuel pump was replaced about 2.5 months ago. Looking at the service records and reciepts, this car had all the usual suspects already replaced or cleaned recently, except probably the fuel injectors. The hoses look fairly new. No cracks in them and seem tight. Despite that, I hear hissing and a high pitched whine. I can't find where it is coming from though because it only happens when I am driving and only every now and again. Sounds like a plane taking off or landing. This may be unrelated. I have no idea as it also started all the sudden.

Other stuff: The check engine light is not on. This car does not leak or burn oil. The idle is even rougher in reverse. Engine temp reads normal.

Any help would be appreciated!

 

Fuel Pressure Regulator and fuel filter. Change them both and you should be good.