Car start somtime, somtime not.
Thread Starter
Track Day
Joined: May 2002
Posts: 21
Likes: 0
From: Iceland
Car start somtime, somtime not.
I would like to ask for help with my 1990 Carrera 4. I have 80160 mile on it.
Starting with rarely and progressing to frequently my car stalls and won't start again.
When I try to start again it seems like it almost starts up but it doesn't run. (After cranking for some time it starts to smell of fuel from the exhaust.)
The strange thing is that occasionally when I come back to it after several days (maybe after some checking) it starts right up and runs fine for couple of hours. I have not been able to identify whether this happens after working on the motor or not. Sometimes when it runs I leave it idling outside. (Getting tired of being towed back home if I try to drive it) It will then shut down normally, but the morning after it will not start again. There is no pattern. Sometimes it shuts down while driving and sometimes it doesn't start up in the morning.
Then there is another strange thing going on. When the car is finally running, (these couple of hours) sometimes all warning lights light up and a warning chime sounds. When this happens, the motor does not stall, but continues to run fine. I dont know if these two problems are connected or not.
I have taken it for Porsche shop computer readout but no fault codes were found. (It even shut down while the readout was being taken with no indication)
Here is a list (not in right order) of what has been done to try to find the problem. (I was fortunate enough to borrow identical car to pull parts.)
Swap the ECU controllers. (My car didn't start the other car ran fine for days.)
Change DME relay. (New)
Swap the anti theft controllers.
Test the wiring harness from ECU to motor.
Test the wiring harness on motor.
Disconnect Oxygen sensor.
Swap Engine Speed sender.
Check all earth connection points.
Swap intake manifolds with everything, sensors, injection etc.
Check fuel pressure.
Please help me, I'm running out of ideas.
Best regards
Halldor Johannsson
Starting with rarely and progressing to frequently my car stalls and won't start again.
When I try to start again it seems like it almost starts up but it doesn't run. (After cranking for some time it starts to smell of fuel from the exhaust.)
The strange thing is that occasionally when I come back to it after several days (maybe after some checking) it starts right up and runs fine for couple of hours. I have not been able to identify whether this happens after working on the motor or not. Sometimes when it runs I leave it idling outside. (Getting tired of being towed back home if I try to drive it) It will then shut down normally, but the morning after it will not start again. There is no pattern. Sometimes it shuts down while driving and sometimes it doesn't start up in the morning.
Then there is another strange thing going on. When the car is finally running, (these couple of hours) sometimes all warning lights light up and a warning chime sounds. When this happens, the motor does not stall, but continues to run fine. I dont know if these two problems are connected or not.
I have taken it for Porsche shop computer readout but no fault codes were found. (It even shut down while the readout was being taken with no indication)
Here is a list (not in right order) of what has been done to try to find the problem. (I was fortunate enough to borrow identical car to pull parts.)
Swap the ECU controllers. (My car didn't start the other car ran fine for days.)
Change DME relay. (New)
Swap the anti theft controllers.
Test the wiring harness from ECU to motor.
Test the wiring harness on motor.
Disconnect Oxygen sensor.
Swap Engine Speed sender.
Check all earth connection points.
Swap intake manifolds with everything, sensors, injection etc.
Check fuel pressure.
Please help me, I'm running out of ideas.
Best regards
Halldor Johannsson
Racer
Joined: Jun 2001
Posts: 370
Likes: 0
From: New Zealand
Hi,
Sounds like you're not getting ignition or its running so rich it washes the spark. Have you checked the coils, caps, rotors, HT Leads, Distributor belt. What's the battery condition like? Check the battery earth lead.
Good luck
Ade.
Sounds like you're not getting ignition or its running so rich it washes the spark. Have you checked the coils, caps, rotors, HT Leads, Distributor belt. What's the battery condition like? Check the battery earth lead.
Good luck
Ade.
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Joined: May 2001
Posts: 8,027
Likes: 17
From: Parafield Gardens
Dear Iceman,
Tough seeing you have done so much but I will give you my ideas.
Check the dual coils. They do fail and they are intermittant.
Check the secondary distributor drive belt.
Check the connection of the hall sensor at the primary distributor. Hall sensor kaput then no start.
Functional check of the ingition system in general as suggested by Ade.
Check the airflow sensor and the connector.
Ignition switch (my favourite for the dark horse)
You indicate you have the Xmas tree effect. This is caused by theignition switch or the harness leaving the engine bay to the ECU but you say you have checked this.
Ciao,
Adrian
911C4
Tough seeing you have done so much but I will give you my ideas.
Check the dual coils. They do fail and they are intermittant.
Check the secondary distributor drive belt.
Check the connection of the hall sensor at the primary distributor. Hall sensor kaput then no start.
Functional check of the ingition system in general as suggested by Ade.
Check the airflow sensor and the connector.
Ignition switch (my favourite for the dark horse)
You indicate you have the Xmas tree effect. This is caused by theignition switch or the harness leaving the engine bay to the ECU but you say you have checked this.
Ciao,
Adrian
911C4
