I'm in need of community help once again.
I have one of the cars that recently suffered engine failure due to the alleged oil starvation issue. I decide to buy a salvage yard engine rather than rebuilding or buying a new one. I just replaced the engine and got everything connected and fluids filled. I let the car run on the lift for about 10 minutes to check for leaks and let the coolant circulate so I could top it off. I turned the car off and did a few other things to finish off. While doing this I left the key on, my car is a turbo so the intercooler electric pump runs while the key is on so I ran the battery dead. I jump started the car and took it out for a test drive. I got about 100 yards down the road when the engine cut out. I let it sit for about a minute and tried to start it again. It started right up and ran for 2-5 seconds and cut out again just like it was out of gas. I tried this a few more time with exactly the same results.
I disconnected the fuel line just in front of the rear tire. When I turn the ignition on the pump gives a 1/2 second shot of fuel then stops. When you crank the pump delivers fuel for 2-3 seconds then stops. I removed the fuel pump and connected power to it. It delivers good volume and pressure outside of the car with direct power applied. I put everything back together and get exactly the same symptom. I'm also getting a generator error but no fault codes. I don't know if this is an actually error or just one of the system that must reset after major service.
In my opinion something is telling the pump to turn off, either a bad part (relay, fuse, switch, ...) or the computer is not happy about something. Any thoughts?
Let me start by answering a few of the questions first
My car is a
2006 Cayman S
with a TPC turbo.
The engine came from the same year car.
I'm using my original computer.
The fuel tank is full.
I have checker all the fuses in the fuse panel.
Kermit, my knowledge on this is somewhat dated but I'd be surprised if
Porsche
changed the system entirely. Check the pump relay. Not sure where it's at on a
Cayman
but expect that it still exists. Also there should be a signal from the ignition to keep the relay pulled in when the engine is running. Not sure where this would come from now. Lastly check the voltage when cranking. If it's falling too low, below ~8vdc if I remember correctly, the ECU won't run. Dead battery might be getting you here.
Thanks for the help.
We did think of the battery issue. Voltage looks good but we even connected it to a second battery and got the same problem. While running the voltage goes to 14 so it looks like the alternator is working.
I wasn't meaning running but cranking voltage. If cranking voltage falls to low the pesky computers won't work. However, trying a second battery should have covered this.
I'm thinking
PIWIS
is my only hope. I'll look for the relay and see if I can swap it out with a different one.
Any other ideas?
Just to check over all of the electrical connectors that were disturbed in the engine swap. There is still probably a signal from the engine to pump relay coming from the ignition, flywheel sensor etc to show the engine is running. Safety feature in case the engine stops so the pump doesn't keep running. If one didn't snap in it might of shook loose when you started driving. Bit of a long shot but cheaper than a dealer diagnosis and tow.
The 4 oxygen sensor plugs, mass air sensor, exhaust fan, transmission switch, and the battery cable are the only electrical connection done during an engine swap. But possibly the crank sensor in the new engine is bad.
Great suggestions, I’ll check the connection. If that does not work I’ll swap the sensor from the old engine. I’m going to keep it till this one is running correctly just in case I need more parts.
So what are the forum rules…….
If you find the problem and it’s your own stupid fault, do you have to tell anyone?
My car has the TPC turbo, when the engine was installed we forgot to tighten the clamp on the intake tube between the intercooler and throttle body. Car ran fine but when I took it for the test drive the intake tube blew off when the intake went from vacuum to boost. So basically the mass air sensor was seeing no volume of air so the computer cut the fuel pump.
Put hose back in place and car is running great, problem solved.
