244Droomkey

Hi to all,

91 S4 automatic

I need some help with an intermittent engine stalling issue. I am experiencing a loss of power and engine shutoff primarily in elevated outside temperatures 90°F. Temperature gauge indicating 190°F or less. After abt 15 min the car will restart and run well for abt 45 min and then stall again. It appears some temperature sensitive component is shutting down the engine. Not sure if the shutdown is fuel, electrical or vacuum system. The car is stock with abt 110,000 miles and in good condition otherwise.

Speedtoys

It stalls as you drive it? Only when it idles?

Does it stall suddenly, or get slowwwweerrrr..and then struggle and die?

Kevin in Atlanta

When's the last time you checked cranking end play?

244Droomkey

It shuts down very quickly, I watched the tack drop off to zero RPM in abt 10 sec, I was looking for erratic RPM indication but the shut down was smooth. The shutdowns have occurred mostly under power climbing moderate grades at 60 MPH or more. I have compiled an extensive history if that would help?

John

Speedtoys

Well, oldrelays can go flaky with heat..sound like loss of fuel.

Here:
http://928intl.com/repair/Relay/laterelay.htm

Replace the relays in positions:
IV
V
XXV
XXVI

Get them from:
https://928srus.com/products/copy-of...452f7ab3&_ss=r

Get more than you need, a spare or two isnt a bad idea..these are common failure points for stalling...and like I said, can common be heat related.

Also replace fuse #38, is the fuse melted, the contacts black/arced? Is the fuse socket darkened?

And IMHO, its a good idea to replace all fuses at this age, they corrode and get hot, and drop voltage...etc.

Do the fuse and relays, report back.

244Droomkey

Thanks!!!
The car is down at the local Porsche Shop and I will pass you information on. In May we cleaned all of the ignition contacts and connectors, changed out all fuel filters, and replaced the crank sensor.
John

Speedtoys

..but not what actually ages on a 928, the $5 relays....great Porsche shop.