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98 C2 - Car fires then dies - Urgent Help Required Please

Reddahaydn

New member
Joined
20 Jun 2019
Messages
3
Hi Guys,
I'm meant to be hitting the track the next 2 days but I went to start my car yesterday and it won't hold. It's a 1998 C2.

It feels like it fires, taco jumps to 1000 them it just dies straight away.
It did this consistently.

Prior to this I washed the car, drove it 5 meters back into the garage, and then I pulled rear carpets and seats out. No signs of any issues.

About 800 kms ago the ecu was removed and it was tuned (It's a 1998 so they said they couldn't tune it via OBD). Has done 800kms with no issues since the tune.

We have removed harness bar and cover plates and checked all rear ecu plugs
Removed passenger seat and checked security ecu plugs and fuse
Turned fuel pump on and it still squirts fuel up the back
Checked all fuses
Scanned codes - there are no current codes coming up. There was a stored security code - possibly from when ecu was removed to tune the car.
Dash turns on as normal, no other signs of any issues
Put a new ignition switch in
Hooked a new battery up to mine as mine was dying after trying a few different things
My mechanic reckons compression sounds fine, we are going to check that today.

When we have it plugged in was can see that the the start enable switch setting within the ecu isn't opening.

I cannot find anything on the 'start enable switch' on google, being that it's not a actual switch that you can replace.

Does anyone else have any ideas on what it could be?
Am i right to rule out security ecu, since it allows the starter motor to turn the engine?
Same theory on the clutch switch?
Anything else that it could be?

Thanks in advance!
Haydn
 
Apparently the fuel system works when we manually turn it on with his diagnostic computer, however it isn't getting turned on when we try and start the car.
So I think the relay is OK, but maybe it is something to do with the immobiliser? Does the immobiliser let the engine crank, but cuts fuel?
 
It can do if it's the cut-off to the fuel pump that's faulty.
 
If its an Immob problem the car will start and run for 3 seconds
Then cut out. Have you a spare key to try?

Can you hear the fuel pump prime or run?
 
Haydn, Sorry I have not worked on an ECU controlled Porsche, thus anything I type could be nonsence... I have no idea of the control stratedgy, though I would tend to agree that if the starter engages and the ignition system creates sparks, the injectors allow fuel to flow for even for a short time, then using no more than simple Logic I suspect the ECU might be looking for oil pressure to have reached a degree of pressurisation before allowing the engine to run on....? Oil pressure switch faulty or corroded connection at it..?

Just thinking in type.
 
A cheap OBD2 reader may show some fault codes to get you in the ballpark?
 
Sorry, re read the Op's post, ignore last!
 
No fault codes indicate a system that's not monitored .. fuel system and CPS spring to mind ..

You open the door and the fuel pump will prime .. that will be enough to start the car but if it doesn't see a cps signal after that it will cut out ..

Scope the cps signal .

TERM 15 RELAY .. Perhaps check this .. volt meter .. it this switching off when not in start position on the ign lock

same check with fuel pump relay

It strikes me as the car either doesnt know its spinning over after release from start to ign or it looses the ign on via the relay.

If you hold it on the starter it should run for a bit longer than just releasing the key after staring.. don't do this for long as the starter is engaged .

A visual check of the alarm control unit is in order , your are looking for water damage to the circuit board .

It doesn't strike me as a water / immobiliser fault .. the car will not crank but its a check none the less to do .

My guess is CPS or a wiring fault to the term 15 relay atm .
 
Reddahaydn, many thanks for posting detail of the resolution to your system failure. Very much appreciated :thumb: :thumb:
 

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