Engine dies
06-29-2006, 08:27 PM
#1
Track Day
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Engine dies
1989 928 s4
Oh NO car starts normally but as soon as the temperature warms at first increment on temp gauge the car shuts down as if I turned the key off. After shutting down I have to wait for it to cool before attempting another start about an hour
Oh NO car starts normally but as soon as the temperature warms at first increment on temp gauge the car shuts down as if I turned the key off. After shutting down I have to wait for it to cool before attempting another start about an hour
06-29-2006, 08:35 PM
#2
Burning Brakes
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Temperature Sensor 2 ??? doesn't it drop the signal to the LH and EZK modules upon failure..killing both the injection control / fuel pump and ignition ? Or else perhaps the Flywheel position sensor....would have this sort of effect. But would NOT be temperature related....Good Luck my friend... 
06-30-2006, 12:51 AM
#5
Under the Lift
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Nasty thoughts there, Garth. Before we go there....
Paisan:
Randy's guess is worth ruling out. Swap one of the other "53" relays (horn, blower, etc) into the FP relay position and see if that stops the problem.
Determine if you have spark after the shutdown by pulling a plug and shorting against the head. If you have spark, then it is not the flywheel sensor. Unplug the LH brain and check the resistance across the harness plug pins 13 and 5. If it is anything other than zero or infinity, temp sensor 2 is probably OK (hot engine reading should be 300-400 ohms). Let's take it from there after you look at those items.
Paisan:
Randy's guess is worth ruling out. Swap one of the other "53" relays (horn, blower, etc) into the FP relay position and see if that stops the problem.
Determine if you have spark after the shutdown by pulling a plug and shorting against the head. If you have spark, then it is not the flywheel sensor. Unplug the LH brain and check the resistance across the harness plug pins 13 and 5. If it is anything other than zero or infinity, temp sensor 2 is probably OK (hot engine reading should be 300-400 ohms). Let's take it from there after you look at those items.
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06-30-2006, 08:39 AM
#8
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About 3 minutes it shuts down I will check all the other things people have suggested. too bad porsch didn't just put an on and off switch under the hood it would make this much easier
06-30-2006, 10:30 AM
#10
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I doubt temp sensor 2, because if it fails the engine LH reverts to "hot" settings as a default condition. So this would give difficult starting, but OK running when hot.
When the engine dies, does the rev counter drop instantly to zero, or does it follow the engine rpm ?
This can give some clues.....
When did you last release the flex plate tension ?
When the engine dies, does the rev counter drop instantly to zero, or does it follow the engine rpm ?
This can give some clues.....
When did you last release the flex plate tension ?
06-30-2006, 05:17 PM
#11
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When the engine is in a no-start state, confirm that you have sufficient spark. If there is no spark, start EZK relay and check the RPM sensor etc.
If spark is OK, then go onto these tests.
a. Check these relays:
- LH
- EZK
- Fuel pump
If your horn works, the quickest check would be to pull one out one-by-one and plug in the horn relay and try to start each time. If it starts up then you've found the bad relay.
If this doesn't help, remove all three relays.
- check the relay socket 30 position for battery voltage, it should be there with the ignition turned off. If there is no voltage, you have to fix that circuit (corroded connections at the battery?).
- with confirmed voltage at the 30 point, jumper between the relay socket 30 and 87 positions. Do you hear the fuel pump running? If not, repair the pump or circuit.
If the engine doesn't start, then you need to go through a full diagnostic test. Fuel pressure, fuel delivery, many other circuits. It could be corroded wiring contacts (they heat up and resistance increases), a defective ignition switch, or your LH could be on the way out.
If spark is OK, then go onto these tests.
a. Check these relays:
- LH
- EZK
- Fuel pump
If your horn works, the quickest check would be to pull one out one-by-one and plug in the horn relay and try to start each time. If it starts up then you've found the bad relay.
If this doesn't help, remove all three relays.
- check the relay socket 30 position for battery voltage, it should be there with the ignition turned off. If there is no voltage, you have to fix that circuit (corroded connections at the battery?).
- with confirmed voltage at the 30 point, jumper between the relay socket 30 and 87 positions. Do you hear the fuel pump running? If not, repair the pump or circuit.
If the engine doesn't start, then you need to go through a full diagnostic test. Fuel pressure, fuel delivery, many other circuits. It could be corroded wiring contacts (they heat up and resistance increases), a defective ignition switch, or your LH could be on the way out.