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tholyoak

7.8 DME integrated into '99 Boxster (3.6L Swap continued)

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Finally found some time to work on the car yesterday. I integrated the 2002-on 7.8 DME and egas into my '99 Boxster to run the 3.6. I had been running the 3.4 DME (5.2.2) with a piggyback controler since November but I wanted the factory setup. I still have the early 996 instrument cluster, and didn't update any of the other electronics (yet) beyond the DME (same keys, same immobilizer, same HVAC etc). So it is possible to put the later DME into earlier cars without updating all of the other systems. I did loose cruise control right now, but I will hopefully have that solved when I get some more time.

All systems check out via the PST2, I do have a CAN bus timeout error on the cluster and PSM since the car has neither of those CAN bus systems. I may update to the later instrument cluster if I can pick one up reasonably.

Todd

Edited by tholyoak

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Well done! On cars with DME7.8 the cruise is controlled in the later instrument cluster, not like 7.2 where it was controlled in the DME. However, if you are using the original cruise system for 99 cars, this is totally independent of the DME, so it's strange that it stopped working.

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Richard,

It is simply the mechanics of the pedal assembley. The cruise cable can't hook the same to the egas pedal assembley. I am going to upgrade the cluster so it will only be a short term issue. The DME and cluster communicate a number of functions via the CAN bus.

Todd

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You do some really impressive work with the Boxster, Todd. Where do you get the information from to do all this work? How did you know that it was going to work? And how do you figure out the necessary new connections that are needed? Was this a matter of plug and play or are there extra wirings and/or adaptations needed? What extra features does the new DME provide?

Sorry about all these questions, but this is really impressive. It's like you were part of the Porsche engineering team. You were not part of the Porsche engineering team, were you? :)

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It really isn't too difficult to figure out, just takes some time. Most of the info is in various Porsche documentation, primarily comparing the wiring diagrams. It is definitely not plug and play like the 3.4 conversion into the early cars. I had to make a conversion harness in order to integrate the 7.8 DME connections into the '99 chassis. It was a bit more involved since I used a 2001 986S engine harness and had to make some modifications to it as well. If I had a later 2002- engine harness it would have been a bit easier.

Based upon driving the car so far, I don't think the factory setup is much better, if at all, than running the 3.4 DME with the piggyback (I am still waiting on the proper MAF, so I can't say anything conclusive yet). It certainly is a lot less work and $$ to use the piggyback setup. However with the current setup, it could be taken to any Porsche shop and they could plug it into the PST or PWIS and work on the car.

Also it looks like I need to upgrade the HVAC and cluster as the AC doesn't work as there is no input on the new DME for AC triggering, it is received from the AC control via the instrument cluster on the CAN bus. Oh well, I'm sure I could figure out how to get it to work without upgrading, but the whole point was to have a factory like installation. But for a track car there would be no need to upgrade anything except the DME and egas setup.

Todd

You do some really impressive work with the Boxster, Todd. Where do you get the information from to do all this work? How did you know that it was going to work? And how do you figure out the necessary new connections that are needed? Was this a matter of plug and play or are there extra wirings and/or adaptations needed? What extra features does the new DME provide?

Sorry about all these questions, but this is really impressive. It's like you were part of the Porsche engineering team. You were not part of the Porsche engineering team, were you? :)

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Just to update, I have all the CAN bus systems integrated and everything seems to be working just fine and the PST2 confirms that. Sort of interesting to have the dot matrix display cluster in a '99 Boxster. Anyway, for those that want to do this you will need 2002- 996 cluster (or 2001- Boxster cluster), the later CAN bus HVAC controller and the later CAN bus ABS controller. In addition if your Boxster is not E-gas you will need the complete egas pedal assembly. This is in addition to the engine and 7.8 DME, and modying an engine harness. Then it is a matter of wiring it all up.

Todd

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Finally found some time to work on the car yesterday. I integrated the 2002-on 7.8 DME and egas into my '99 Boxster to run the 3.6. I had been running the 3.4 DME (5.2.2) with a piggyback controler since November but I wanted the factory setup. I still have the early 996 instrument cluster, and didn't update any of the other electronics (yet) beyond the DME (same keys, same immobilizer, same HVAC etc). So it is possible to put the later DME into earlier cars without updating all of the other systems. I did loose cruise control right now, but I will hopefully have that solved when I get some more time.

All systems check out via the PST2, I do have a CAN bus timeout error on the cluster and PSM since the car has neither of those CAN bus systems. I may update to the later instrument cluster if I can pick one up reasonably.

Todd

Hallo Todd

Is it possible to tell me what moifications you made in order to run your boxter with the 7.8 DME.I remind you that I put an 3.6 engine to a Carrera 4 3.4.I am still have problems with the Vario cams.I control the valve lifts with an external circuit but I cannot correctly control the cam timing.With the solenoids of variable timing connected, the car has a constand fluctuation on the RPM's.When I dicconnect them it is kind of slow at low RPM's but it's ok at high RPM's.So now I am thinking of replace the 7.2 DME to a 7.8 in order to have the correct solenoid controls.The only difficulty is that I have to have the engine head dismount in order to change again the ignition cam disk to an 3.6 original one because the one that I use now its converted(cutted) like the 3.4 engine.

So Todd what would you do in my case?If you have any idea how I may do this engine to work correctly I would appreciate it and of course if you are able to sell me any documantation of the convertion it would be fine.Thank you

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Drop me a personal message or email through the board and I'm sure I can help you get things sorted out. You essentially have two options, 1) integrate all the necessary wiring and systems to get the later DME into your car, or use the same piggyback setup I used prior to integrating the 7.8 DME into my car.

Todd

Finally found some time to work on the car yesterday. I integrated the 2002-on 7.8 DME and egas into my '99 Boxster to run the 3.6. I had been running the 3.4 DME (5.2.2) with a piggyback controler since November but I wanted the factory setup. I still have the early 996 instrument cluster, and didn't update any of the other electronics (yet) beyond the DME (same keys, same immobilizer, same HVAC etc). So it is possible to put the later DME into earlier cars without updating all of the other systems. I did loose cruise control right now, but I will hopefully have that solved when I get some more time.

All systems check out via the PST2, I do have a CAN bus timeout error on the cluster and PSM since the car has neither of those CAN bus systems. I may update to the later instrument cluster if I can pick one up reasonably.

Todd

Hallo Todd

Is it possible to tell me what moifications you made in order to run your boxter with the 7.8 DME.I remind you that I put an 3.6 engine to a Carrera 4 3.4.I am still have problems with the Vario cams.I control the valve lifts with an external circuit but I cannot correctly control the cam timing.With the solenoids of variable timing connected, the car has a constand fluctuation on the RPM's.When I dicconnect them it is kind of slow at low RPM's but it's ok at high RPM's.So now I am thinking of replace the 7.2 DME to a 7.8 in order to have the correct solenoid controls.The only difficulty is that I have to have the engine head dismount in order to change again the ignition cam disk to an 3.6 original one because the one that I use now its converted(cutted) like the 3.4 engine.

So Todd what would you do in my case?If you have any idea how I may do this engine to work correctly I would appreciate it and of course if you are able to sell me any documantation of the convertion it would be fine.Thank you

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are you changing the interior wiring loom as well cause i thought that the clusters pre/post clusters do not have the same connections

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You will need to wire in new connectors for the cluster, that is correct. There is also some other wiring additions that are made, depending on the year of the car.

Todd

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Wow!! I was just hoping to figure out how to get a 3.4 in a 98 someday. This is incredible.

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You will need to wire in new connectors for the cluster, that is correct. There is also some other wiring additions that are made, depending on the year of the car.

Todd

so you used the original pre facelift wiring loom with a post facelift cluster did you cut the connectors from a post loom and wire them into the pre loom

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The pins from the old connectors can be removed and used in the new connectors for the updated cluster. Some of the wires need to be extended to reach their new connections as well as a few new wires added that don't exist on the old harness such as the CAN bus wires for the HVAC and the engine.

Todd

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The pins from the old connectors can be removed and used in the new connectors for the updated cluster. Some of the wires need to be extended to reach their new connections as well as a few new wires added that don't exist on the old harness such as the CAN bus wires for the HVAC and the engine.

Todd

can you explain what a can bus is and do you have wiring diagrams for the post facelift cluster i have the cluster just need to know how to wire it i am very experienced at wiring but do not know what the can bus is

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looked it up on the glossary has my car got this it's a 2.5 what do i need

still answering my own questions all i need is where can i get the connectors plus the extras for the extra wires and a wiring diagram

im based in england but anywhere that has email will do

Cheers its good to see other people who like pushing the envelope on what can be done to a car

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Only the later cars used a CAN bus system. Essentially rather than a single wire transmitting a single signal between the various controls of the car, many signals are passed over a single twisted pair of wires. For example there is a CAN bus network between the cluster and the engine DME, there is another between the radio, the cluster, and the ABS/ PSM controller.

If you have a tiptronic it is on another CAN bus network.

Todd

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Only the later cars used a CAN bus system. Essentially rather than a single wire transmitting a single signal between the various controls of the car, many signals are passed over a single twisted pair of wires. For example there is a CAN bus network between the cluster and the engine DME, there is another between the radio, the cluster, and the ABS/PSM controller.

If you have a tiptronic it is on another CAN bus network.

Todd

no its a 98 manual with TC climate memory seats is it not possible to do on a 98 car

Edited by alstarz88

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Only the later cars used a CAN bus system. Essentially rather than a single wire transmitting a single signal between the various controls of the car, many signals are passed over a single twisted pair of wires. For example there is a CAN bus network between the cluster and the engine DME, there is another between the radio, the cluster, and the ABS/PSM controller.

If you have a tiptronic it is on another CAN bus network.

Todd

no its a 98 manual with TC climate memory seats is it not possible to do on a 98 car

yes it is possible

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This is the information I needed. I have purchased the 3.6 with 40K miles on it, 996 instrument cluster, and lightweight flywheel. According to what you wrote above I WILL need the 7.8 DME and a few connectors for my 2000 Boxster S. Thanks for all you detailed info I have used it and questioned my mechanic that will be doing the work and the tuning company providing the software. I take your knowledge very seriously as you have done this and they have not yet. I look to have my kit in in the next month.

Josh

Now a supporting member

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Very interesting; I'm ordering the 996 tiptronic instrument cluster; the HVAC and the ABS control module ; do I need something for the tiptrionic?

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Only the later cars used a CAN bus system. Essentially rather than a single wire transmitting a single signal between the various controls of the car, many signals are passed over a single twisted pair of wires. For example there is a CAN bus network between the cluster and the engine DME, there is another between the radio, the cluster, and the ABS/PSM controller.

If you have a tiptronic it is on another CAN bus network.

Todd

How can I make these CAN BUS wires. Ineed to make the ones etween the cluster and DME, and ABS controller.

What kind of wire is used? Are the connector special?

Thanks

Kare

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Can bus wires are nothing special, just a twisted wire pair. CAT5/6 cable is a good source for twisted pair wire.

-Todd

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Can bus wires are nothing special, just a twisted wire pair. CAT5/6 cable is a good source for twisted pair wire.

-Todd

Impressive. Looking at this from the opposite end, what is needed to add the dot matrix cluster to a 99? New HVAC? And ABS-controller? Or does it need to communicate with the DME?

Atle

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