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Simon K

996 engine swap coding DME. Immobiliser

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Hi, I have a '99 model 996 that has had a previous engine swap, an '02 engine fitted. The car hasnt been going since the swap (6 years ago) and has found its way to me to get going.

I will fill you in on what has happened, the original engine, DME, immobiliser was all sold together (gone) and from what I can tell the second new owner has supposedly bought a matching DME, Immobiliser and key from a wreck. The car wont crank or enable the DME. The key operates the doors but thats it.

I worked out that the replacement DME is out of a 986. I have a pst2 but not sure where to go not having the original DME and Immobiliser.

If anyone can give me a hand I would be very grateful as I have hit a brick wall, a new brain on the job would be great. Thanks Simon.

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The '99 and '02 DMEs are incompatible. There are substantial differences between '99 and '02, not the least of which are the introduction of eGas and Variocam Plus. The car will need a substantial amount of re-wiring in order to get it to run.

Unless you have the IPAS codes for the DME and Alarm/Immobiliser, and also if they are not the correct type, they will be useless to you, as they can't be reprogrammed without the codes.

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If it is the DME/immo combo, I recommend sourcing a 1999 996 immobilizer/ DME/key combination set that all came out of the same car. If the car is not USA, source one that is ROW. That way it should be plug and play without any programming required.

If you get any other 5.2 DME, or a DME with a different immo for example from a 986 then you'll need codes which is a nightmare.

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oh right, missed the part about the 2002 engine... yep you're right!

Pretty much this combo will not work without extensive rewiring as you pointed out.

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Rewiring the body harness to mate with the 02+ engine harness could work. Other things would need to be swapped also (Dash cluster, HVAC, gas pedal and fuel pump) which might make it not worthwhile....

I had colected a bunch of the swap parts planning to do something similar. I decided the time required wouldn't be worth it. PM me if you need some parts.

Edited by 987_RDC

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One of the biggest problems (besides egas and VarioCam Plus) in trying to use a 2002 DME in a 1999 car is the fact that by 2002, a lot of the subsystem controllers (such as AC, cruise control, etc.) had been moved over to CAN bus technology, which simply did not exist in the 1999 car. Can it be overcome? Sure; with enough time, money, welding rod, and duct tape, anything is possible, if expensive.

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Well if you sourced another 99 996 key, immob and dme -- AND did the rewire -- you should at least get it to start.

You can then figure out some piggy back system to handle the e-gas and vario-cam.

It might all be cheaper/easier to find a chap with a 3.4L, then sell the 3.6L.

Good luck -- (what a mess)

Mike

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The DME supplied is a 99 model but a 986, looks like the original loom has been used and all connected to the 02 engine. I havent looked at the engine wiring in too much detail.

If I have to do something with the cam control later I will cross that bridge then. I have all the ipas codes for the replacement DME, immobiliser and the original VIN codes.

So I can understand the system operation, what has to be coded so that the supplied matching DME/immobiliser will communicate with the car to activate the immobiliser, innitiate the DME to crank the engine and enable fuel pumps etc?

Can I get this engine to run if I get a 996 DME/immobiliser and what is a ROW DME.

Thanks for all the imput, this is giving me a lot more insight to the system.

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ROW and USA are designations. ROW = Rest of World ......ie non-USA. The configurations (specifications, emissions, etc) are different between USA and ROW cars.

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The cam control is going to be tricky. If you were going the other way around, then it would be more simple because the early engines are a simple on/off situation for cam advance.

Going from old to new might be impossible? without a 7.8 version DME. The variable cam system in the 996 2002+ engines is continuously variable based on a variety of conditions, and is not just a simple on/off setup as it is on pre 2002 engines.

Even if it runs, the car may never run quite right, or run as it should. It will certainly be down on power, not to mention probably CEL lights.

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I totally understand logray, thats my thinkig as well.

I at least need to get the car to crank and initiate the DME first. I dont think changing dash, wiring and gas pedal is really an option , as all I can see is this will devalue the owners car and cost alot of money.

I am going to locate a matching 996 DME/ immobiliser and key and go from there. If I locate these units will anything have to be reprogrammed, or will they just operate?

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CAN bus is just two wire communication so add the pins+wires with swapping the instrument cluster and HVAC. (repin the 99 harness to the 02 cluster)

Fuel sytem can be converted to returnless by swapping the complete pump but you need a fuel pump pigtail to add the lines for DME 7.8 control. (should have 02 fuel rails on the newer engine)

Already noted was the e-Gas pedal swap and issues with needing 02+ DME/immobo combo (or at min the VIN from each and good friends at the dealership)

Edited by 987_RDC

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I totally understand logray, thats my thinkig as well.

I at least need to get the car to crank and initiate the DME first. I dont think changing dash, wiring and gas pedal is really an option , as all I can see is this will devalue the owners car and cost alot of money.

I am going to locate a matching 996 DME/ immobiliser and key and go from there. If I locate these units will anything have to be reprogrammed, or will they just operate?

If you dont have the time to make the engine run well, take the 02 engine out and sell it. Buy a 99-01 engine,

A correctly opperating 02 engine in a earlier car should increase the value since higher HP/TQ.

I'm guessing you have an engine harness from the 02 engine. No idea if those pinouts match the body harness of the 99 DME.....worst case the engine harness catches fire. Best case nothing happens......

Any idea on the engine harness, fuel rails, injectors etc? What is 02 and what is 99? Do you have access to PIWIS?

Edited by 987_RDC

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No the pinouts do not match, hence extensive rewiring... best bet would be to use 99 harness on 02 engine, but still, then you are dealing with the nightmares we already talked about.

best advice already given above, sell the 02 engine, source a 99-01 engine...

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best advice already given above, sell the 02 engine, source a 99-01 engine...

+1 from me. If you can find some of Todd Holyoak's posts (tholyoak) about fitting a 3.6 engine to a 1998 Boxster, you will begin to understand the complexities. Sure, it is possible, but is it really worth the huge time and expense? If I were you I would keep it simple, and at the end of the day you will have a standard car, which will probably be worth more than a hybrid.

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