Boxster DME 7.2 to 7.8 transplant

[Phil Holzer]

Hi,

 

I have replaced the 3.4S engine with an IMS bearing failure out of my 2001 Boxster (DME7.2) and with a replacement from 2002 Boxster engine, but with a DME7.8. As I understand it the 2001 model I have has partial CAN bus. 

 

I swapped the engine, gearbox, instrument cluster, immobiliser, key reader module (next to the steering column), the key. I have re-pinned 98% of the ECU plugs to suit the DME7.8 diagram I found on the forum. The wiring is not right though at the multi-pin plugs in the boot and I can't find a wiring diagram for the 2002 model. Not even the Bentley manual has the complete wiring diagram.

 

The cluster displays "engine failure" and of course the engine won't turn-over. I have applied power to the starter and the engine does turn. I have had the ECU/Immobiliser/Key all checked as being ok. The OBDII port won't connect to any reader I have tried, so it feels like an immobiliser problem? The central locking / alarm all seem to work ok. 

 

I'm really struggling now and hate being defeated, but I can't keep shutting the garage door! My son is nagging at me to get it on the road. He seems to think its his car!!!!

 

Any help would be greatly appreciated.

 

 

[mikefocke]

A 2001 with a 3.4 must have had a 996 engine transplant.

 

The 2003 was the first DME 7.8 Boxster engine

[Phil Holzer]

Apologies Mike. It was the original 3.2, not 3.4 engine. The 2002 engine is definitely 3.2 too, but also DME7.8 ECUADOR.

[Richard Hamilton]

Mike is correct that DME7.8 was introduced for MY2003.  If the engine was post-September 2002, it would be MY2003, but it might be worth checking the engine number, just to be sure.

 

If it was a 2003 engine the third digit would be "3".

Did you use the immobiliser pill from the new DME/Alarm/Key set?  The alarm module needs to read a pill which was coded to a matching DME and Alarm Module.

 

Also, if you can't connect to the DME with a code reader, check the W-Line diagnostic wire between the alarm module and DME.  It uses the diagnostic line to transmit the immobiliser signal.

Edited December 31, 2017 by Richard Hamilton

[Phil Holzer]

Thanks Richard, I’ll double check, but I’m certain it’s a DME7.8. The registration plate is also 2002, so must be a late model?

 

i used the original key fob and just changed the blade. So the pill should be matched to the ECU.

 

I did send the ECU, immobiliser and key set away to be tested, which was returned as ok.

 

Because the OBD port appears to be blocked from reading anything it still feels like a problem with the immobiliser. I understand that the Porsche reader can read the port even if immobilised. I guess I will have to try and find a specialist. 

 

[Richard Hamilton]

Was it a 52 plate?  If so, it might well be MY2003.

 

You should be able to connect to the DME with a code reader, even if the immobilizer is active. 

[xr_guys]

Hi Phil,

 

Did you resolve this issue, i have exact problem with the transplant 7.2 to 7.8 DME. 

 

2002 Boxster S 6 speed with coolant intermixed issue, replacement engine is a 2003 Boxster S. No crank start, OBD2 not connecting and engine failure error flashing.

 

Thanks,

XR

[Phil Holzer]

Hi,

 

Yes, managed to get it running. Actually had it MOTd and on the road this week. Still a few bits to do, but couldn’t resist top down motoring, since the sun shines so rarely here in the UK.

 

You need to get hold of the proper 2003 wiring diagram, it’s easy once you have this. The one on the pelican parts web site is no good, ignore it, it’s a red herring. Wasted far too much time with it.

 

I assuming you’ve used the 2003 engine wiring loom and DME7.8 ECU.

 

If you took the wiring loom from the 2003 engine, you’d assume that these connections to the ECU would be right and the problem lies with the plugs / loom between the car and ECU. You’d be wrong.

 

From memory and I can check later in the week if you are still struggling, make sure you have the MFI/DI relay wire RD/BN moved from PIN B23 to D26 on the DME7.8 ECU.

 

I assume you will have the obvious plug A wiring repinned, but it was the above one that really stumped me. Once sorted, it fired straight up.

 

After that I’d buy the Autel Diaglink from Amazon for around £80. My generic OBD2 reader didn’t pick up all of faults the Diaglink did. Then work through any other faults. I bought a donor car, heard my engine wiring and in the first instance assumed it was the a wiring issue.

 

There are three multi-pin plugs on the LH side of the rear boot (trunk) on the rear fire wall. Check that the same colour wires go in and back out of these two plugs. Struggled to find tools to remove some of these pins.

 

Sorry if I’m a little vague. I’m not at home at the moment and don’t have all of the info with me at the moment. So let me know if you are still struggling.

 

Do you also need to change from the return to non-return fuel system? If so, I purchased a non-return fuel pump / filter / sender / by-pass unit, second hand off Ebay. Replace the entire lot that sits within the fuel tank. Access is below the battery. Easy to do. I retained the existing fuel filter located under the car. For some reason, I can’t remember why, once I connected the fuel line to the fuel rail it was actually the old return line, so cut the supply line just after the filter and connected it to the line that now goes to the engine. Used a mechanical hydraulic coupler, that was ok for fuel. 

 

Hope this helps

 

 

[xr_guys]

Hi,

 

Yes, managed to get it running. Actually had it MOTd and on the road this week. Still a few bits to do, but couldn’t resist top down motoring, since the sun shines so rarely here in the UK.

 

You need to get hold of the proper 2003 wiring diagram, it’s easy once you have this. The one on the pelican parts web site is no good, ignore it, it’s a red herring. Wasted far too much time with it.

 

I assuming you’ve used the 2003 engine wiring loom and DME7.8 ECU.

I’m using a wire loom that came from a 2003 2.7, the main difference is the reverse back up light connector from 5 spd to 6 spd. All connectors match up. The 2003 engine came from automatic transmission so the wiring loom that came with is different from the 6 spd.  

 

If you took the wiring loom from the 2003 engine, you’d assume that these connections to the ECU would be right and the problem lies with the plugs / loom between the car and ECU. You’d be wrong.

Which side are you referring, the car side connector or the engine side connector?

 

From memory and I can check later in the week if you are still struggling, make sure you have the MFI/DI relay wire RD/BN moved from PIN B23 to D26 on the DME7.8 ECU.

Please if you have time, if you have additional info please share it. I made xls file mapping the 7.2 vs 7.8 DME pin connection, hopefully and if I feel confident enough i will publish it to help others.

 

I assume you will have the obvious plug A wiring repinned, but it was the above one that really stumped me. Once sorted, it fired straight up.

I already moved Terminal 30 to pin A2, waiting for additional order of wire terminal for the A connector. How about the Motor Throttle actuator lines, did you have to move that to A connector from C43 & C44

 

 

After that I’d buy the Autel Diaglink from Amazon for around £80. My generic OBD2 reader didn’t pick up all of faults the Diaglink did. Then work through any other faults. I bought a donor car, heard my engine wiring and in the first instance assumed it was the a wiring issue.

I will check

 

There are three multi-pin plugs on the LH side of the rear boot (trunk) on the rear fire wall. Check that the same colour wires go in and back out of these two plugs. Struggled to find tools to remove some of these pins.

Do you have pictures?

 

Sorry if I’m a little vague. I’m not at home at the moment and don’t have all of the info with me at the moment. So let me know if you are still struggling.

Thanks for your response

[xr_guys]

Phil,

 

Here is the xlsx file pin comparison.

 

Engine side (Cable end attachment to the engine)

Car Side (Cable end attachment to the car)

 

Thanks,

XR

Porsche Boxster 7.2 to 7.8 DME Pin Comparison.xlsx

[xr_guys]

Phil,

 

 Can you please add more details to what pins need to be moved?

 

Thanks,

XR

[78F350]

On 5/31/2018 at 12:43 AM, xr_guys said:

Phil,

 

Here is the xlsx file pin comparison.

 

Engine side (Cable end attachment to the engine)

Car Side (Cable end attachment to the car)

 

Thanks,

XR

Porsche Boxster 7.2 to 7.8 DME Pin Comparison.xlsx

This was awesome to find posted here. I am working on some re-wiring for a swap and was searching for validation of my DME 7.2 spreadsheet. The only difference that I found between this 7.2 pin-out and mine is that I have CAN High and CAN Low reversed - I am working with a 2000 S (986). Connector IV (or D),  I show CAN High on 36 and CAN Low on 37 (as is shown on the 7.8).

-Thanks for posting-

[Steve Cook]

On 5/29/2018 at 7:46 PM, xr_guys said:

Hi Phil,

 

Did you resolve this issue, i have exact problem with the transplant 7.2 to 7.8 DME. 

 

2002 Boxster S 6 speed with coolant intermixed issue, replacement engine is a 2003 Boxster S. No crank start, OBD2 not connecting and engine failure error flashing.

 

Thanks,

XR

Did you ever get your swap sorted? I'm in the same situation (2004 3.2 going into a 2002) and looking for what pins need to be swapped. I've already swapped the ones in your spreadsheet and all the ign coil pins. Are there more pins you had to change?