'99 Boxster Tiptronic not firing after engine overhaul

[JFP in PA]

If the DME is not seeing the engine turning signal from the CPS, it will shut off the fuel and ignition.

[seningen]

Originally Posted by JFP in PA

If the DME is not seeing the engine turning signal from the CPS, it will shut off the fuel and ignition.

Been awhile since I have been down this road.

There is a relay in the back left side of the trunk which I think sources the gnd for the fuel pump relay and the ignition coils.

Any chance the immobilizer got wet? similar symptoms.

[Kice]

Thanks for the quick feedback!

CPS: Though it's brand new (Pelican) and no sign of not working (tests alright), I will get another new one to be absolutely sure it's not that.

Immobilizer: Car was in garage for past 3 years so can exclude that it got wet. Also: would the immobilizer not prevent the engine from cranking in the first place?

Will check the relays in the back.

[JFP in PA]

Originally Posted by Kice

Thanks for the quick feedback!

CPS: Though it's brand new (Pelican) and no sign of not working (tests alright), I will get another new one to be absolutely sure it's not that.

Immobilizer: Car was in garage for past 3 years so can exclude that it got wet. Also: would the immobilizer not prevent the engine from cranking in the first place?

Will check the relays in the back.

Long before aimlessly throwing parts at it, why not check and see if the DME is getting a signal from the CPS? Trace the CPS wires to the connector at the DME and look for a low voltage signal on them at the DME end when the engine is turning over; if you have a signal, it isn't the CPS.

[Kice]

Originally Posted by JFP in PA

Long before aimlessly throwing parts at it, why not check and see if the DME is getting a signal from the CPS? Trace the CPS wires to the connector at the DME and look for a low voltage signal on them at the DME end when the engine is turning over; if you have a signal, it isn't the CPS.

Thanks! Is there a chart for the pins in the DME plug? Or is it best to go by the color coded cables from the CPS?

[JFP in PA]

Originally Posted by Kice

Thanks! Is there a chart for the pins in the DME plug? Or is it best to go by the color coded cables from the CPS?

Service manuals will have a complete wiring diagram.

[78F350]

Originally Posted by Kice

Thanks! Is there a chart for the pins in the DME plug? Or is it best to go by the color coded cables from the CPS?

Maybe pin 78..?
I have a link to this in my folder of DME stuff, Says it's DME 5.2.2: https://www.renntech.org/topic/28597-porsche-996-dme-pinouts-and-connectors/

[Kice]

Thanks. I checked the relays in the trunk per Bentley manual and they all seem ok.

I also measured the voltage directly from the CPS connector when cranking the engine and it clearly produces a signal. So the CPS seems to be fine.

I am however unclear how to check if that signal reaches the DM, because when I disconnect the DME connector to check for the signal on the respective pins the car will not start at all. I guess need to jumper the starter for that test?