944 Stalling

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Tony - 17 Feb 2004 22:42 GMT

My 1987 Porsche 944, 8 valve has developed a heck of a stalling problem.
Anyone experience a similiar problem?

This morning I was heading out for an appointment approximatley 12 miles
away. It was around 45 degrees out, snow melting. I got to the
appointment, car ran very well. Appointment was about 30 minutes. Then
drove to a store about a quarter of a mile away with no problems. Was in
the store about 15 minutes. On my way, I got as far as a half a mile and
the car stalled. I was doing around 35 mph. I pulled over, started the car
and it died within a minute. I let it sit for about 5 minutes and managed
to drive about a eighth of a mile. I swapped out my spare DME Relay and
even tried jumping the relay with no luck. The longer I let the car sit,
the farther I could go. It took me about 8 cool down periods and 2 hours to
drive the 12 miles back home.When it ran, it ran ok. I tried to get it up
over 60 mph, so I could coast further before pulling over. The connections
for the fuel injectors, speed and reference mark sensors, air flow metter
looked good. Seems like a temperature problem, but I don't know why I could
make the 12 mile trip one way with no problems, but the return trip required
so many cool down periods. The engine had to have warmed up on the way to
the appointment. Has anyone solved this problem?

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Brian Moore - 18 Feb 2004 08:12 GMT

Sounds like the problem I had---see earlier posts--- it was fuel pressure
regulator

> My 1987 Porsche 944, 8 valve has developed a heck of a stalling problem.
> Anyone experience a similiar problem?
[quoted text clipped - 16 lines]
> so many cool down periods. The engine had to have warmed up on the way to
> the appointment. Has anyone solved this problem?

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Tony - 19 Feb 2004 02:08 GMT

Thanks for the tip, but no, I just did a thorough check of the fuel system.
Pressure and leak down are ok. I replaced the regualtor about 2 years ago.

Funny thing. When check the voltage on the Air Flow Sensor (pin 9 I think),
I only get 5 volts as opposed to the 8 volts stated in the Haynes manual.
Also when checking resistance of pins 2 (closed throttle) and 3 (wot) of the
throttle position switch against engine ground, I get nothing. But the
readins between pin 2 and 18; and pins 3 and 18 match the book values. Is
the throttle position switch supposed to be ground to the engine/body?

> Sounds like the problem I had---see earlier posts--- it was fuel pressure
> regulator
[quoted text clipped - 24 lines]
> > so many cool down periods. The engine had to have warmed up on the way to
> > the appointment. Has anyone solved this problem?

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Brian Moore - 21 Feb 2004 14:18 GMT

I've seen some talk in the rennlist that moisture in the fuel can freeze in
the fuel line in extreme cold and cause problems--- maybe look there or at
Clark's garage through Pelican Parts? I don't know--- good luck

> Thanks for the tip, but no, I just did a thorough check of the fuel system.
> Pressure and leak down are ok. I replaced the regualtor about 2 years ago.
[quoted text clipped - 42 lines]
> to
> > > the appointment. Has anyone solved this problem?

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Tony - 22 Feb 2004 22:57 GMT

Thanks Brian, but it's not freezing now, and I have the car in the garage.
I'm losing my mind over this problem. If the car sit overnight or for
several hours, it starts right up and runs fine for about 10 minutes. The I
can start it again and it will run for about 1-2 minutes. After that, it
won't start until it sits for a while.

I thought it may be a thermal break down problem and double checked the temp
sensors on the engine and in the air flow sensor. Even by-passed them with
resistors of 300, 400, 1000, and 1400 values. I have taken the computer
apart and stick it in the freezer in the event a component is heating up.
Both cases, no luck. When the car stalls, I still have battery voltage to
the computer and injectors. The resistance readings of the speed and
reference mark sensors are good. Throttle body switch and Air Flow sensor
are good.

I just replace the fuel regulator and that didn't do it. I have double and
triple checked all sensors and connections. Looks like a fuel problem as
you suggested. I wonder if a bad check value at the fuel pump would cause
these type of problems.

> I've seen some talk in the rennlist that moisture in the fuel can freeze in
> the fuel line in extreme cold and cause problems--- maybe look there or at
[quoted text clipped - 57 lines]
> > to
> > > > the appointment. Has anyone solved this problem?

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Paddington - 19 Feb 2004 22:48 GMT

> My 1987 Porsche 944, 8 valve has developed a heck of a stalling problem.
> Anyone experience a similiar problem?

Seems like a temperature problem, but I don't know why I could

> make the 12 mile trip one way with no problems, but the return trip required
> so many cool down periods.

I don't have the answer to your problem, but I've driven my 86 944 when it
was as cold as -20 F outside, an OAT of 45 degrees would not be an issue
unless there is some kind of other extenuating circumstance with your car.

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Garry W. Elmer - 28 Mar 2004 15:50 GMT

A little late but we have a 1985 1/2 944. The throttle position switch can
wreak havoc. Worse yet, it's mounted in such a way they eventually you can
get moisture down into it and foul the contacts. I am not sure of all of
the different ways it can foul up but ours would stall above 1500 RPM. The
Haynes book has a test that should tell the story. Taking the switch off is
not difficult. When you do though, shake it around and see if you get any
water out of it. When in doubt, replace it.

http://www.thepartsbin.com is a great place to get parts.
Garry
Mystic, CT

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