'99 Boxster Tiptronic not firing after engine overhaul

[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?

[blue62]

Originally Posted by 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?

Use a Multi Meter to check continuity and for short to ground on the respective pins

[JFP in PA]

Originally Posted by 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?

No, the CPS is a Hall Effect sensor, it only has to turn over to generate a signal, it does not need to run.

[Kice]

Originally Posted by JFP in PA

No, the CPS is a Hall Effect sensor, it only has to turn over to generate a signal, it does not need to run.

Understood, but how do i get the flywheel to turn with the DME (and hence the starter) disconnected so i have access to the DME connector pins?