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ziiz996

3.4L to 3.6L Conversion NIGHTMARE

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Loren my Dear Porsche Nut,

Do you know the lo speed fans kickoff temperature for an 02-04 996? And the Hi speed temps as well?

Are both left and right fans supposed to come on together? at lo and ho speed?

They used to, before the transplant!

LOL - 1 to 1 conversion schematics? Those don't exist unless you or Todd whats to create them. You need a service manual with schematics.

Please read through Todd's posts (in other threads) to see where he got the pin tools.

Replacing a car harness is a 2 day job - even for someone that is familiar with it. I don't recommend it.

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Todd,

If you could help with the conversion tables I would really appreciated.

J.

Todds_Old_to_New_Connector.doc

The issue with the temp and the cooling fans most likely is a result of not correctly wiring up the coolant temp sensor. The 3.6 uses a single NTC element, the signal is provided to the DME which interprets the resistance as a temp and controls the actuation of the blowers and also sends the temp signal to the cluster via the CAN network. The older motors use a double NTC element, one part is used for the dme, the other is the signal directly to the temp gauge and warning lights on the cluster. Not knowing what was done, leads me to believe this is the most likely problem. The other possibility would be the incorrect HVAC controls, since the fans are also cycled by the AC may be leading to the lack of the low speed fans.

Todd

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Looking at your little sheet you don't seem to realize that there are 26 pins on each of the old instrument connectors and 32 on each of the new ones. You also don't seem to realize how much work this was for me to figure all of this out.

For the pin removal/ installation for the cluster connectors you don't actually need any special tools, just remove the outer coloured casing and it is quite obvious how to remove the pins with a small pin or screwdriver.

Todd

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Loren my Dear Porsche Nut,

Do you know the lo speed fans kickoff temperature for an 02-04 996? And the Hi speed temps as well?

Are both left and right fans supposed to come on together? at lo and ho speed?

They used to, before the transplant!

LOL - 1 to 1 conversion schematics? Those don't exist unless you or Todd whats to create them. You need a service manual with schematics.

Please read through Todd's posts (in other threads) to see where he got the pin tools.

Replacing a car harness is a 2 day job - even for someone that is familiar with it. I don't recommend it.

Yes, together.

http://www.renntech.org/forums/index.php?s...ost&p=83062

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Loren my Dear Porsche Nut,

Do you know the lo speed fans kickoff temperature for an 02-04 996? And the Hi speed temps as well?

Are both left and right fans supposed to come on together? at lo and ho speed?

They used to, before the transplant!

LOL - 1 to 1 conversion schematics? Those don't exist unless you or Todd whats to create them. You need a service manual with schematics.

Please read through Todd's posts (in other threads) to see where he got the pin tools.

Replacing a car harness is a 2 day job - even for someone that is familiar with it. I don't recommend it.

Yes, together.

http://www.renntech.org/forums/index.php?s...ost&p=83062

Thanks Loren. Now I know that my Lo speed fans are not working. At one point only the passenger Lo speed fan came on at the lower temp. And "our famous Tooner"(Sorry I have the word Looser on my mind) tried to convince me that Only the passenger Lo speed fan comes on at the low temp setpoint!! But he even somehow managed to disable the Pass Side Lo speed fan on one of my many drop-offs at his shop after his allegation that the "job was complete". Thank you again.

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Looking at your little sheet you don't seem to realize that there are 26 pins on each of the old instrument connectors and 32 on each of the new ones. You also don't seem to realize how much work this was for me to figure all of this out.

For the pin removal/ installation for the cluster connectors you don't actually need any special tools, just remove the outer coloured casing and it is quite obvious how to remove the pins with a small pin or screwdriver.

Todd

So Sorry Todd!

:oops: I managed to leave out the extra column for the second bank of connectors on the sheet/table that I sent you.

I was trying to make it simpler by making it look more like the connectors. (L and R side). Feel free to add columns or extra rows per table if you prefer.

I TOTALLY understand that this is not a small job. But I really thought that you must had gone through the diagrams first, wrote down the conversion charts of you re-connections on a sheet/table of some sort, then re-wired, instead of re-wiring directly from the diagrams!

Thanks,

Jacomo.

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Loren my Dear Porsche Nut,

Do you know the lo speed fans kickoff temperature for an 02-04 996? And the Hi speed temps as well?

Are both left and right fans supposed to come on together? at lo and ho speed?

They used to, before the transplant!

LOL - 1 to 1 conversion schematics? Those don't exist unless you or Todd whats to create them. You need a service manual with schematics.

Please read through Todd's posts (in other threads) to see where he got the pin tools.

Replacing a car harness is a 2 day job - even for someone that is familiar with it. I don't recommend it.

Yes, together.

http://www.renntech.org/forums/index.php?s...ost&p=83062

Thanks Loren. Now I know that my Lo speed fans are not working. At one point only the passenger Lo speed fan came on at the lower temp. And "our famous Tooner"(Sorry I have the word Looser on my mind) tried to convince me that Only the passenger Lo speed fan comes on at the low temp setpoint!! But he even somehow managed to disable the Pass Side Lo speed fan on one of my many drop-offs at his shop after his allegation that the "job was complete". Thank you again.

The fans are controlled by the DME which is getting (shared) information from the cluster. This is why Todd said it was important to get all the pieces that work together. There is a lot of communication on the CAN bus on the MY02 and newer cars that just was not there in the MY01 and older cars.

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Sorry to hear about your troubles. Can you mention where you had the work done? At least in which state they are located? :)

I'll be needing this done as well.

Edited by pjalexandre

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Sorry to hear about your troubles. Can you mention where you had the work done? At least in which state they are located? :)

Not in VA. So Don't worry. Not worth mentioning the name...

However be aware that the engine transplant will not be successful if you do not replace a whole lot of other parts on the car (Another 6 to 8K Plus Labor$$$). The VarioCam Plus will not function and therefor you end up with less power than the 3.4.

My recommendation:

If your engine runs fine, then either bore it out to 4.0L (Under 10K) and kick some serious NA bu&**% or Supercharge (RUF$$$$$ or TPC(11K'ish); I don't like the third guy; low end torque and then all hell brakes loose at the last 1500 RPMs which I think will put a lot of load on an engine that I have come to realize is sub-par by Porsche Racing Standards: (wet Sump and manufactured in Japan!!))

GT3 or Turbos have Dry sump and are developed and manufactured at Porsche Racing division).

If your engine is on its way out, then trade it in ASAP and get an 04 GT3 or even an 01+ Turbo. At least you know that your are paying your money on cars that were designed to be driven (instead of being shown off). DON'T DO IT.

If my tuner wanna be was honest with me up front, I would have sold my C2 Cab (dead engine in my case) for as low as 20K and invested the time and $$$ that I spent so far on a used GT3 or a 996 Turbo.

TRUST ME not the guy who is using you passion for driving high performance cars, to take your MONEY.

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If your engine runs fine, then either bore it out to 4.0L (Under 10K) and kick some serious NA bu&**% or Supercharge (RUF$$$$$ or TPC(11K'ish); I don't like the third guy; low end torque and then all hell brakes loose at the last 1500 RPMs which I think will put a lot of load on an engine that I have come to realize is sub-par by Porsche Racing Standards: (wet Sump and manufactured in Japan!!))

The 996 motors are made in Japan?

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ziiz996,

Sorry you're dealing with such a mess.

If you get the wiring diagrams for the two cars (the 3.4L and 3.6L) you can look at where each pin in the connector goes in both cases and write it down. Then do the conversion by swapping the wires appropriately. It will require some time and patience but it shouldn't be too difficult.

I would concentrate on looking at the wiring diagrams. Anything that communicates via CAN bus (the things mentioned earlier in this thread) will have to be replaced and connected to the CAN bus wires. It's not that complicated, really. You may have to tell the DME (using a PST2 or PIWIS) about the new CAN bus items. (I've never done it but that makes sense since they are coded).

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Wow - Ziiz996, very sorry to hear about what you're dealing with.... but now I have to ask a question of Loren and Todd on this thread given how knowledgable they are about conversions...

I've been playing with the idea of putting a 996 GT3 motor and turbo transaxle in my '02 996 C4S. This would be instead of supercharging the 996 engine and seeing if I can re-gear the 996 transmission (or just the final drive - do you know if someone offers a different final drive?). I know all the rational arguments for why I shouldn't even think of doing it but I love the car, love what I've done to it so far and the way I have it dialed in at this point, and am curious to know if this is a reasonable option.

Do you know if anyone has done this successfully and/or if I will encounter electronics issues?

Thanks for your time and opinions.

-Lu

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lu - since you already have an 02 3.6 I think in your case it's not as bad, he is going from an older 3.4 to the newer 3.6.

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Electronically the 3.6L GT3 uses the same DME as the regular motor so you shouldn't have any issues.

You have to ask the question why?

For the $35k a GT3 engine will cost you, you could sell your car and buy an actual GT3. Same reason I think that sticking a 3.6 in a 3.4 car is a poor use of money as you can just buy a 996 3.6 (i.e. a later car). The reasons that we stick the bigger motors in the boxster is the fact that Porsche doesn't sell this car so it makes it worth the effort in my view.

Todd

Wow - Ziiz996, very sorry to hear about what you're dealing with.... but now I have to ask a question of Loren and Todd on this thread given how knowledgable they are about conversions...

I've been playing with the idea of putting a 996 GT3 motor and turbo transaxle in my '02 996 C4S. This would be instead of supercharging the 996 engine and seeing if I can re-gear the 996 transmission (or just the final drive - do you know if someone offers a different final drive?). I know all the rational arguments for why I shouldn't even think of doing it but I love the car, love what I've done to it so far and the way I have it dialed in at this point, and am curious to know if this is a reasonable option.

Do you know if anyone has done this successfully and/or if I will encounter electronics issues?

Thanks for your time and opinions.

-Lu

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Looking at your little sheet you don't seem to realize that there are 26 pins on each of the old instrument connectors and 32 on each of the new ones. You also don't seem to realize how much work this was for me to figure all of this out.

For the pin removal/ installation for the cluster connectors you don't actually need any special tools, just remove the outer coloured casing and it is quite obvious how to remove the pins with a small pin or screwdriver.

Todd

So Sorry Todd!

:oops: I managed to leave out the extra column for the second bank of connectors on the sheet/table that I sent you.

I was trying to make it simpler by making it look more like the connectors. (L and R side). Feel free to add columns or extra rows per table if you prefer.

I TOTALLY understand that this is not a small job. But I really thought that you must had gone through the diagrams first, wrote down the conversion charts of you re-connections on a sheet/table of some sort, then re-wired, instead of re-wiring directly from the diagrams!

Thanks,

Jacomo.

Hi guys

How is the this conversion chart project going forward? I am also in need to do this job...

Does anybody has the 7.8 DME and 2002 onwards instrument cluster wiring diagrams for 996?

Saludos,

Kare

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Hey guys,

My car had an engine failure as well and I decided to upgrade to a 3.6 instead of just replacing with another 3.4. I am picking up my car this Friday as it is all done. I am really excited to pick it up. Will be taking a picture of the 3.4 with a connecting rod sticking out.

Of course this post makes me nervous. Hopefully I'll have better luck. Will post my observations as I have a very long drive home from the shop with the car.

-Paul

Edited by pjalexandre

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Paul,

Were did you have yours done? Aprox how much did it cost? What are your thoughts on power & driveablility?

Thanks,

Shawn

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Hey guys,

My car had an engine failure as well and I decided to upgrade to a 3.6 instead of just replacing with another 3.4. I am picking up my car this Friday as it is all done. I am really excited to pick it up. Will be taking a picture of the 3.4 with a connecting rod sticking out.

Of course this post makes me nervous. Hopefully I'll have better luck. Will post my observations as I have a very long drive home from the shop with the car.

-Paul

Hi there!

was curious to know what happened with your upgrade... Since you haven't replied yet, this is worrying! Please give us some feedback on your results when you can. Thanks

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Actually Loren my car runs the proper 7.8 Motronic setup. Originally I ran the 5.2.2 with an aftermarket controller, but that was just an interm solution until I obtained all the parts I need to integrate the 7.8 DME into my '99 Boxster. Your 2000 996 should have been a much simpler proposition.

You need to replace a lot of components to have everything work. If you send me a PM I would be glad to help you out. You will get some idea of what is required by looking at my posts on the boxster section

Sounds like they didn't modify the wiring harness properly or upgrade the necessary components so the 7.8 DMEcan communicate with the other systems properly.

Todd

Hi there Todd,

I'm not sure i understood this correctly, but you are saying that you have been using an aftermarket controller in order to control the variocam lift solenoid...

I have done the same, and would really like to know what made you give up on it and preffer to go through this solution. What is it that you observed with the aftermarket controller? (poor idling, delayed return in low valve lift when rpms drop etc). If those were your symptoms do you think it was due to that controller's quality or what? i'm asking 'cause i'm looking for a better quality controller myself, one that has a quicker response in activating and especially deactivating the solenoids. I believe the whole problem is caused by the lack of throttle pedal position input signal to this controller. By the way, did you used to get the engine speed signal from the cluster, or from another source? Please suggest a specific brand of controller if you have something in mind.

One last question: do you believe that the returnless fuel system is actually mandatory as Loren suggested earlier in the beginning of this forum?

Happy holidays by the way, to you and everyone in the forum! (this would also include a wish for no more problematic conversions lol)

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ziiz996,

Sorry you're dealing with such a mess.

If you get the wiring diagrams for the two cars (the 3.4L and 3.6L) you can look at where each pin in the connector goes in both cases and write it down. Then do the conversion by swapping the wires appropriately. It will require some time and patience but it shouldn't be too difficult.

I would concentrate on looking at the wiring diagrams. Anything that communicates via CAN bus (the things mentioned earlier in this thread) will have to be replaced and connected to the CAN bus wires. It's not that complicated, really. You may have to tell the DME (using a PST2 or PIWIS) about the new CAN bus items. (I've never done it but that makes sense since they are coded).

Hi there

I´m still looking for different options for my 996 MY99 cabrio engine swap from 3.4 to 997 3.8 one.

I have the complete engine, with engine harness. Now I found a guy who would sell me a brand new 2002 onwards instrument cluster, 7.8 DME, airbag control unit, 2 remote keys, inmobilizer unit, air cond unit, rear and front control unit and complete 997 car wiring harness for about $2300. Looks like a very interesting option,or what do you think?

He said this would be a "plug and play" for my engine. But... LOren said in one of thew posts that changing the engine harness is a complicated job. If I choose this route, what elese do I need for the set up to work? The ABS unit, or...????

And what will happen with my convertible top controlling? How is the control unit wired, to the DME, I suppose?

Saludos,

Kare

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Hi all,

With the holidays I forgot about this thread but did post about it elsewhere.

I picked up the car as stated and proceeded to drive it home ~650 miles about 10 hours or so. Drove the car locally with the mechanic to get a feel for it and make sure everything was to my liking.

1st impressions.... started car up cold, everything in the dash and hvac works as it should. Car fired right up and with stable idle like it should, air injector whirring for the first few minutes. Drove it around easy for 20 minutes to warm it up once the temps and oil were up I had a bit of fun. A bit more low end torque then I remember and above 3500 it is a lot more fun then it was. 1st gear sometimes gets a little wheel spin as it passes 4K to redline. Feels good except that I already getting used to it.

Drove home and since the speed limit is 70mph most of the way I was doing 80+ the whole way. Got 27mpg on 2 tanks that way with more than a few acceleration runs up through the gears.

Car has been really good the last few weeks. Had a little scare with my temp light coming on after starting it up but that was just an air bubble coming out that required me to re top up the coolant tank since it was now low. No issues at all the last few days with it.

Overall very happy with it, feels pretty strong and agressive in the top range of the RPM. Other 3.4 and 3.6 owners that I have given rides to also felt that the top end was notably strong and pulled pretty hard relative to their cars.

Happy Holidays... and post note special thanks to Loren, search feature provided me with a nice post explaining all the functions of the temp gauge and why/when the light flashes. :)

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I know this thread has been quiet for some time, but I'm hoping to get a heartbeat again with some questions I have on this conversion.

I am getting ready to embark on this 996 3.4 to 996 3.6 journey. I have a 2000 996 C2 3.4. I just purchased a 2002 3.6 complete engine with DME/ECU (7.8), wiring harness from ECU back to the engine, immobilizer, instrument cluster and ignition key head all from the same car. I have some questions:

After doing some reading on this thread, I have come to the conclusion that I am going to need a little rewiring even with the electronics I am buying. Can someone confirm this please?

Will I need to upgrade my ABS controller and HVAC controller to work properly (and not throw codes on durametric)?

Given the list of stuff I am purchasing, will I have an issue with the variocam + not working properly? From my understanding, the issues are mostly when dealing with intergrating an earlier version of Motronic (5.2.2 or 7.2) to the 3.6 engine.

Any other insight is appreciated.

Thanks,

Ken

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I know this thread has been quiet for some time, but I'm hoping to get a heartbeat again with some questions I have on this conversion.

I am getting ready to embark on this 996 3.4 to 996 3.6 journey. I have a 2000 996 C2 3.4. I just purchased a 2002 3.6 complete engine with DME/ECU (7.8), wiring harness from ECU back to the engine, immobilizer, instrument cluster and ignition key head all from the same car. I have some questions:

After doing some reading on this thread, I have come to the conclusion that I am going to need a little rewiring even with the electronics I am buying. Can someone confirm this please?

Will I need to upgrade my ABS controller and HVAC controller to work properly (and not throw codes on durametric)?

Given the list of stuff I am purchasing, will I have an issue with the variocam + not working properly? From my understanding, the issues are mostly when dealing with intergrating an earlier version of Motronic (5.2.2 or 7.2) to the 3.6 engine.

Any other insight is appreciated.

Thanks,

Ken

I think your biggest issue is going to be the CAN bus system differences between the 2000 chassis and the 2002 engine and its DME. In 2000, CAN bus existed, but very little was communicating over it; by 2002, a lot was happening on the bus for the 7.8 DME, and that is one area where you are going to have a lot of compatibility issues. This will not be an easy swap without a lot work, including the differences in the fuel systems.

You might want to contact a poster here named Todd Holyoak (called "tholyoak"), who has done this type of swap for more details on what you need to do.

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I have a PM to Todd about this. I'm still waiting to hear back. I'm trying to get smart on the conversion now before the stuff gets here next week. I did add the ABS and HVAC controller to my order, all from the same car.

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In general, if you want a factory-type situation and maintain all functions and diagnostics etc, you need to replace the DME with the 7.8 DME. In my experience, no other solution will make you happy for a street car. To integrate the 7.8 DME, you need to change out the ABS controller, the instrument cluster, the HVAC controller and the DME. Depending on what ABS system your car currently has, you may need to change out the ABS wheel sensors as well. The integration of all components will require rewiring for all controllers as well as likely new connectors for the cluster and likely the ABS controller (again, this depends on the ABS/TC system you have). The CAN bus then needs to be run between the new controllers. The instrument cluster acts as the CAN bus hub so a twisted pair of wires needs to be run from the DME to the cluster, cluster to ABS and cluster to HVAC. I think a 2000 already has egas, so you don't need to worry about swapping the pedal assembly and running the wires from the pedal to the DME.

The hardest part, once you figure out what needs to be done, is staring at the corresponding wiring diagrams for your current car and a car that came with the 7.8DME and figuring out how/where to swap all of the wires.

Good luck,

Todd

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