924Board.org

[firemn131]

Ok hear it goes again.

Problem: After running for 10 minutes or sometimes 60 miles it will lose power and stop. I have to let it sit from 10 to 45 minutes then it will turn over and run until it decides to stop again.
In the last 6 months I have changed the following;
Fuel pump relay
fuel filter,
fuel pump
fuel pressure sensor.
so now what.
the problem is that it is so random that i can't test it, or drive in confidence. I really like this car but I have to try an justify continuing to throw money at it or get a newer 928.
Help me keep my 924s.
So computer? coil?
thnx john
_________________
1987 924S Daily driver 64 miles each way to work.
2001 F-150 my back up
1970 Mercury Cougar XR7 The Muscle.

[gohim]

Your problem is:

#1 The DME Relay (did you install a brand-new one when you replaced it or did you drop in a used one from someone's junk box? Did you buy a new one and tested it to keep as a spare? Now would be a good time to try installing it.).

#2 The Brain Box (bad or deteriorating solder joints are a common problem).

#3 The Flywheel Sensors (could be a bad sensor. or a bad connection where the sensors are connected to the wiring harness at the top, rear, of the engine block).

With the exception of the DME relay, I would not have expected any of the parts you wrote that you changes to have fixed the problem.

[firemn131]

The relay was new.

the other items were replaced for other reasons. It was just that I have seen these referred to as possible culprits.

The fuel filter was due.
I got a great deal on a newer fuel pump.
relays were replaced prior, to have a good baseline when I first bought car.

As far as the Flywheel sensor. That is a new thought.
However you comment about,,,,

'With the exception of the DME relay, I would not have expected any of the parts you wrote that you changes to have fixed the problem."


I am glad that I was able to make you feel good about yourself.

If only we could all be that smart. Do you always need to try and be passive aggressive and put people down after you assist them?

I will check into the sensor. Thanx
_________________
1987 924S Daily driver 64 miles each way to work.
2001 F-150 my back up
1970 Mercury Cougar XR7 The Muscle.

[Paul]

Also check the engine grounds especially the one under the heater valve.
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

[firemn131]

I will check that tomorrow.
I checked the Flywheel Sensors and they seemed in tact. Wiring looked good and no change in rpm or running condition when wiggled a bit.
I started it up after a week. I could not get it to reproduce the problem. The last time it went away for about 4 months.
But I t did wander in rpm after it was warmed up. the color and intensitie of the exhaust also changed. From clear to a typical cold day exhaust to a little dark. Last week when before I changed the FPR, the exhaust was wet. Black wet. OIL and fuel I thought. That has gone away I think. I tapped on the DME while running and still it ran fine.
I ran some errands and it ran good.
Before I went on my little drive, I pulled all vacuum lines one at a time. No real change. I also pulled the distrib. cap and cleaner the contacts a bit.
I guess it is not going to be my daily driver anymore until I find a spare DME to test it out with.
Anyone have one?

Thanks for all of the input.
John
_________________
1987 924S Daily driver 64 miles each way to work.
2001 F-150 my back up
1970 Mercury Cougar XR7 The Muscle.

[fennacf07]

I'm not sure I agree that your speed/reference sensors are the issue. These sensors are magnetic impulse/hall effect type sensors and when they fail they fail. I've never seen this type of sensor fail intermittently.

When you experience the loss of power do you have any other symptoms that you experience? Does the car die completely or will it idle?

Does it occur more often when you drive it hard or does it not matter? I'm leaning toward your coil but am curious what other symptoms you may have.

[firemn131]

There seems to be no patern, except it has always been at operating temp.
I will always start right up. the last time i drove to work 60 miles and it started chugging when I came to a light and started to slow down. just before that when at 60 mph i could feel a loss of power. it would maintain speed but not excellerate. almost like it was self priming if that makes any sence. So when it started to chugg at the light i pulled over and it died.
I came back to it an hour later and drove it the rest of the way to work2 miles.
At the end of the day on the way home I went about 4 miles and it started to die. After I pulled over it shut down. About 40 minutes later after intermittently trying to get it to start it started and kept running for about 40 miles. While it was shut down for the 40 minutes I held an ice pack to the dme module and also put in my spare relay. neither of these things seemed to be the fix. after the 40 mile jaunt it Shut down and it took another 30 minutes to make it the rest of the way home. It does seem to search for the correct rpm quite a bit though.
john
_________________
1987 924S Daily driver 64 miles each way to work.
2001 F-150 my back up
1970 Mercury Cougar XR7 The Muscle.

[firemn131]

sorry I just reread your question.
it gradually dies. it has never just shut off with out warning. Maybe the coil?
I may just change the coil, plugs and cap/rotor just cause it hasn't been done in at least 25,000 miles.
john
_________________
1987 924S Daily driver 64 miles each way to work.
2001 F-150 my back up
1970 Mercury Cougar XR7 The Muscle.

[Paul]

That list of parts is unlikely to cause the issue you are having.

Check the grounds, then get a factory shop manual and run through the DME troubleshooting. It's a long procedure but it almost always finds the issue.
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

[Paul]

Having said the official line, I would check the TPS and AFM then start the procedure.
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

[firemn131]

I thought maybe the coil. I have an f-150 {i know an entirely different animal} but it had the same power loss thing going on and the coil fixed it.
You don't mean the Haynes manual do you?
_________________
1987 924S Daily driver 64 miles each way to work.
2001 F-150 my back up
1970 Mercury Cougar XR7 The Muscle.

[firemn131]

TPS AFM

Are these Throttle position sensor
air f------- m------?
_________________
1987 924S Daily driver 64 miles each way to work.
2001 F-150 my back up
1970 Mercury Cougar XR7 The Muscle.

[fennacf07]

"It does seem to search for the correct rpm quite a bit though. " Does this happen all the time or only when its acting up? Does your gauge search over a large span or a few hundred rpm?

Clarks Garage has an online manual that might help too.

http://www.clarks-garage.com/

Andrew

[firemn131]

It searches occasionally. Most of the time it evens out. I think that when it dies it just gradually idles down with out the search.
It goes from about 700 rpm to about 12 or 1300.
_________________
1987 924S Daily driver 64 miles each way to work.
2001 F-150 my back up
1970 Mercury Cougar XR7 The Muscle.

[firemn131]

does anyone have a good part number for the dme on a 87 924s.
is the dme also the ecu?
what is the AFM?
_________________
1987 924S Daily driver 64 miles each way to work.
2001 F-150 my back up
1970 Mercury Cougar XR7 The Muscle.