960 cuts out/stalls

The part about the power dropping and the tach going to zero (I presume you are saying the tach reads zero although the engine hasn't quite stopped turning) is a familiar symptom of trouble with the ignition "power stage." Unmounting the power stage, cleaning the mounting faces well and applying heat sink compound from an electronics or computer store typically corrects the intermittent. Anyway, it's cheap and easy enough to try! The power stage is the only ignition component I know of that can cause the fade-away. More often I think of fuel delivery.

If it isn't the power stage getting hot, (particularly if you are saying the tach seems to follow the engine speed faithfully) I would suspect either the fuel filter (debris that falls to the bottom when the pump shuts off ) or the old standby, an intermittent fuel pump relay. Many people have resoldered the circuit board in the fuel pump relay with good results, and careful examination in good light often reveals any cracks in the solder around the leads.

Mike

Additionally, what about problems with the ignition switch and related wiring?

Disconnect and reconnect the computers' main plugs.

Being that it restarts immediately I don't think it is a failing component but a bad connection AT some component or alond a wiring harness.

If a fuel filter clogs it can stop a car, but it usually takes a minute or two with the car not running for the filth to settle to allow fuel flow again. The immediate restart that he is expeiencing rules that out, generally. (BTDT with a Ford PU- ended up a rusty fuel tank. The rust would clog the filter, and when it stalled out the rust settled and the truck would restart.)

I wonder if the computer is setting any codes that could be read in the OBD?

I might also suggest replacing the fuel pump relay(s), and removing the fuses, cleaning all connection points in the fuse box, and replacing the fuses.

That should keep the mechanic busy for a bit. __ __ Randy & \ \/ /alerie's \__/olvos '90 245 Estate - '93 965 Estate "Shelby" & "Kate"

Typically, ignition failures cause the engine to turn off very suddenly, while fuel supply failures have a short fade-out... longer at light throttle. But that is only an indicator and shouldn't completely exclude the other system. The tach is a great clue, because if the tach drops like a stone while cruising down the road we can say it is definitely ignition.

I won't argue with that at all, because the electrical inputs to the ECU can definitely cause fade-away failure.

I agree that it usually takes a while for the filters to uncover - longer than the second or so to shut off and restart the ignition. But it could happen.

The OP said nothing about a "check engine" light, which offers a few clues. Fuel pumps quitting don't normally set the light (I don't know why), and ignition failures from the power stage on also don't.

My '93 960 had similar symptoms a few years ago. It wasn't too long before the car would not restart. A little probing with the multimeter indicated no signal at either power stage module. The computer had to be replaced. Ouch! I miss my 740's.

Sounds like my problems with my 1994 850.

Cruising along and bah-zip, coast to the side and wait twenty minutes or so. Alternately, I'd be making short trips and the car won't start.

Cam position sensor having a heat-fault was suggested and that cost me $400 for the same results as before. I've also had the fuel shutoff relay/selenoid/switch posed as an alternate (co-worker had this with the honking big diesel pickup and seems similar) and someone suggested disconnecting the computer so that the memory resets (beein suggested in this thread as well...)

Yeah, I'll be driving along, lose engine power(some or all), but as I'm still coasting with plenty of speed the tach steadily drops down towards

1. The mechanic had replaced one other part first before the ignition control modules, but I couldn't find my work order and wasn't sure what it was when I posted. I checked on the car and it must have been the power stage as it looks new and recently replaced. The weird thing is that when the power stage was replaced(I presume), the problem did go away for a number of weeks, but eventually returned. Also, my mechanic did indicate when he was able to reproduce the problem once he had some diagnostics of some sort that told him it was a ignition problem, not a fuel problem. Sorry for leaving out some information, this problem has been going on for months, so its easy to leave out some details.

I'm not sure about the comments about a loose connection. Usually once the car starts missing or I lose power the only way to get the car running normal is to shut it off then back on. I would think a loose connection would give me mort of a cut out/cut back in kind of symptom.

I'm not sure where that leaves me. I've kinda been wondering if it is indeed the computer(as rgarrett suggests), but I'm not any kind of expert and would just be guessing. Any additional thoughts? Thanks for your feedback, Micah

The symptom went away for a few weeks when the power stage was replaced, eh? My interest in the mounting is renewed! If the mechanic cleans under it and mounts it with heat sink compound (not factory standard, but recommended here) I think you just may have a solution. If not, at least it rules out a major suspect pretty cheaply. And the tach behavior really sounds like a power stage overheating.

Mike

Another problem in the same area is that each power stage grounds separately on either side of the motor mount and sometimes one or the other will work loose.

Bob