wrhopcraft

I didn't drive my '91 964 for a month or so during the winter (as usual). It ran terribly during the first drive after its 'vacation', so over to the shop it went (barely made it there). Mechanic found a huge mouse house in the engine compartment and evicted the critters pronto. Car wouldn't restart once we got to the shop. After putting in new plugs and wires, the car starts and runs fine - but for only a few minutes. After that, just breathe on the gas pedal and the motor dies. It then needs to sit for a while before restarting. Fuel pump pressures are fine. We haven't seen any wires chewed by mice. The mechanic (who is a Porsche-only guy with his own shop and 25 years' experience) is stumped. Any ideas what to look for next?

One other thing - the small red dash light for the alarm used to go blink - blink - blink. It's pattern is now blink blink - blink blink - blink blank. Is this a clue?

Thanks!!

Rocket Rob

How fresh is your fuel filter? Could it be clogged? Will the engine run on idle for a long time? Have you tried to pull the DME error codes?

Indycam

Is the air flow meter wire/connector disconnected ?

Indycam

He said the car ran into the garage . A clogging up fuel filter will take time to go from ok fuel flow to so clogged up that is fails to flow enough fuel for anything or a tick over .
I think we are looking for something in the engine compartment that was done when the wires were being replaced .

wrhopcraft

Indycam - I don't think anything happened during the wire replacement. Like I said, I barely made it to the garage. Stalled at every stop sign. Very lucky for me, the 5-mile run to the garage is almost all downhill or I definitely would been calling for a flatbed. The only change after replacing the plugs and wires was that the car will at least run decently for a few minutes. Coils, maybe?

Indycam

On the way to the shop you had the rpm over 3000 rpm and then after the work was done you can't get it past 1000ish rpm .

Indycam

Have you had a look see at the sparks ?
It would be very odd for the coils to work at 1000 rpm and then fail at 1100 rpm .

wrhopcraft

3000 revs at most on the way to the shop, but no ability to accelerate. After the work, it will run clean and strong to 5000 within the first few minutes of starting. Then, after those few minutes, idle is all I can get.

jimq

O2 sensor disconected? Probaby not but its near plug wires.

elbeee964

Those ARE some stumping symptoms!

Almost sounds like fuel filter... but sensitivity just off idle would mean a wickedly plugged unit. (And high pressure + low flow (ie, at idle, or off) doesn't neccessarily mean high pressure (given a bum filter) when flow goes up a little.)
A combination of semi-crapped filter + older/crappier "vacation storage" gas, perhaps? (But here, again, Porsche limping can compensate for some fairly crappy gases around the world with better results than yours... so, no easy answer there, either.)
Change $25 filter, suck out the gas tank, and put in $10 of gas, perhaps?

Fuel/air ratio being bummed up by crapped/crapping MAF rheostat, or barn door flapper? (these are robust, so I'm embarrassed to suggest as problem. But, FWIW, check resistance of MAF contacts against WOT & idle positions?)

Crapping alternator causing partial voltage system glitching? (I dunno - it's a Hail Mary pass - but checking system voltage would knock that old bugaboo out of long odds contention.)

Or, a Ferrari-lovin' mouse planting an inconspicuous fault-ground bite on some instrumentation wire.
[shaking clenched fist] (Damned Ferrari-loving mice!)

Hang in there, dude.

Indycam

Topolino ?

When the motor stops running , you can't get it to run for a few minutes ?
If that is the case , check your ground wires .

Run the fuel pump with a dme relay jumper to see if the fuel pump will stay running .

If you give it a little shot of starter fluid when it has shut itself off , will it fire up on the starter fluid ?

wrhopcraft

OK, guys, I passed all of your suggestions on to my mechanic and here is the latest.

First, I neglected to mention that my car is a turbo, so a few responses were not applicable.

Replacing the fuel filter was the first thing my mechanic did when I brought the car to the shop. Spark is good at all times.

Could there be a tie-in with the blinking pattern of the alarm light? Is the pattern a code for a fault that could account for the problem?

elbeee964

Umm... alarm light, as in the LED in the door lock plungers?
Or, as in the 'Check Engine' alarm light?

If the later, then look here.

wrhopcraft

The LED on the dash that blinks when you lock the doors.

Indycam

If the spark is good at all time , then you have a fuel problem .
Does the fuel pump stay running if you run power to it ?
Or does it fail ?