My car keeps going dead

Birmingham Bill · 10-06-2005, 07:00 AM

At first my 1990 911 only went dead when the engine was cool (and not that often). Yesterday, even when the engine was warm, it went dead at every stop sign, red light, etc. Any idea what could be happening? I realize it is quite dangerous, especially when crossing busy intersections.

DW SD · 10-06-2005, 07:11 AM

you may want to clarify what "went dead" means. Engine died I assume? What precipitated? What happens when it is restarted? Does is it run normally?

Far More info would be helpful.

Doug

jdowty3 · jdowty3's Garage

We need more detailed info to help. Is the engine stalling when it drops to idle or do you think you are losing electrical connectivity which kills the engine?
If it's stalling, maybe the fuel filter is plugged or something is stuck (open or closed) in the emmissions system?

jstobo · 10-06-2005, 07:34 AM

DME Relay.

yelcab1 · 10-06-2005, 07:40 AM

Sounds like a vaccuum leak. Potentially.

Birmingham Bill · 10-06-2005, 08:24 AM

When I come to a stop, the engine simply turns itself off. I have to quickly crank it again and rev the engine to keep it running. When I stop at the next light, etc., it shuts down again. The last time I cranked it (last night in my neighborhood) it didn't seem to be running smoothly. There is no warning - it just shuts down. Like I said, it did it a few times last week, on the way to work in the mornings. It seems to run better when I am moving and keep a constant speed. Thanks for any ideas you might have. I don't want to drive it again until I figure out what is going on.

ken_xman · 10-06-2005, 08:26 AM

Whats you warm standing idle "RPM's" set currently?

Birmingham Bill · 10-06-2005, 08:34 AM

Sorry. I have no idea.

ken_xman · 10-06-2005, 08:36 AM

the tach... engine speed.... the vroom meter.
1... to ... 7 in a circle - with a red moving stick

SC Schrauber · 10-06-2005, 09:42 AM

to Birmingham Bill:

"My car keeps going dead

At first my 1990 911 only went dead when the engine was cool (and not that often). Yesterday, even when the engine was warm, it went dead at every stop sign, red light, etc. Any idea what could be happening? I realize it is quite dangerous, especially when crossing busy intersections."

I had the same thing happen to my '81 SC.
Only that I figured the two incidents were not related (hesitation at cold start - I know my Cold Start Valve is not working properly). When the engine warmed up I had the same symtoms like Bill - red light engine out with no warning. I first thought it's the ignition switch. But then I remembered that many years ago an ignition coil went bad on another car only when it warmed up. So I replaced the Bosch CDI, Bosch coil and and ignition wires with MSD CD, Hi-vib coil and magnecore wires. That was my next project anyway. Results: the car purrs like a kitten.
Thanks to many MSD threads here on the board.

How do you like my wire separator solution?

CharlesJones · 10-09-2005, 03:51 AM

Hi Bill,

My 3.2 Carerra keeps doing the same thing which your car does/did, but only when cold. Did you find out what was causing the problem with your car?

With my car whilst cold the revs sometimes drop to zero when I stop at a traffic light or junction, and the engine dies. At other times also whilst cold the revs might drop to about 200 or 300 rpm, but then its as if though the engine management system kicks in and just catches it, returning it to its normal idle speed it before it stalls. Once the engine is warmed up to normal operating temperature this never happens.

My car idles fine otherwise, at about 750-800 rpm, and I have a new coil, ignition leads, distributer cap and spark plugs. I want to try a new DME relay like jstobo suggests, but haven't got round to it yet.

Any ideas anybody?

kqw · 10-09-2005, 08:39 AM

Check the manifold...

Torque the manifold bolts down. Check the torque setting. I know on the carrera's it at 18 ft/Lbs...Don't know about the C2

Symptoms are:

Car cuts out at low rev's or when you stop. Starts righ up again but you have to rev the engine a little higher to keep it running.

Once running it drives fine..

CharlesJones · 10-09-2005, 10:47 AM

Thanks kqw - I'll check my torque settings, but do you mean the inlet manifold or the exhaust manifold?

I seem to remember that in the case of both the inlet and exhaust manifold I had difficulty getting my torque wrench on some of the bolts when I fitted them. In the case of the exhaust I was able to torque up the hex bolts fine because I could get at them straight through the heat exchangers, but for the other nuts I had to just use a spanner and guess the torque. Could this be the cause of my problem? If so I'll make sure I purchase the correct bendy socket extension to get my torque wrench on them.

kqw · 11:15 AM

Your Intake Manifold...top of the engine....

Check for your specific torque settings ( on your 84, it should be 18 ft/Lbs) and make sure you get all of the bolts (12).

A quick test is to spay carb cleaner near the bottom of the Intake manifold and listen for any fluctuation in engine idle.

CharlesJones · 10-09-2005, 02:49 PM

Thanks for your advice - I'll give that a go. I remember the intake manifold bolts as being a nightmare to get at, so I didn't use a torque wrench for most of them, and probably erred on the side of under-tightening rather than over-tightening. I recently bought 1/4inch to 3/8inch socket adapter, so I should be able to get my 1/4inch drive torque wrench in there now.

Thanks again.