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Old 05-11-2018, 07:49 AM   #1
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NO Start issue after Engine swap, HELP!

OK this will be some what lengthy inquiry.

I acquired a 2002 Boxster S with inter mix issue with 87K miles. Replaced the engine with a 2003 model Boxster S with 78K. The donor engine came from a automatic car. Following the Pelican Engine swap advice. Looks like I need to upgrade my ECU to 7.8 from 7.2. I got one from Ebay.

Also I have to source a manual wiring harness from a 2.7 Manual 2002 model. Only modification I did to the wiring is the transmission back up light connector from 5 speed to 6 speed. Wondering why I did not use the old one is because I want to keep the old engine intact complete for resale.

Now mostly got the car together and me and my son trying to start it and the response is not even a crank, dash are all lid up and engine failure appears on the dash. Atempted to hook OBD2 to view error code and failed to connect. Tried two different code reader and both failed to connect. All fuses are good and battery is over 12 volts, no help from battery charger in start mode.

I need idea what can cause this mode on Boxster, looks like security related?

Thanks in advance.
XR
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Old 05-11-2018, 08:22 AM   #2
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the security system consists of 3 parts that needs to match each other.
the emobilizer. located next to the ignition switch.
the alarm system located under the driver seat.
and the ECU located in the trunk.
all 3 of them need to talk with each other. if you replaced the ECU, you need to program it to accept the other 2 units.
with that said, i do not think that an issue with the security system will cause the engine not to crank. i will let more experience forum member make their comments, but meanwhile start with the simple stuff.
override the clutch switch, just to take it out of the equeison.
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Old 05-11-2018, 08:36 AM   #3
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Quote:
Originally Posted by xr_guys View Post
OK this will be some what lengthy inquiry.

I acquired a 2002 Boxster S with inter mix issue with 87K miles. Replaced the engine with a 2003 model Boxster S with 78K. The donor engine came from a automatic car. Following the Pelican Engine swap advice. Looks like I need to upgrade my ECU to 7.8 from 7.2. I got one from Ebay.

Also I have to source a manual wiring harness from a 2.7 Manual 2002 model. Only modification I did to the wiring is the transmission back up light connector from 5 speed to 6 speed. Wondering why I did not use the old one is because I want to keep the old engine intact complete for resale.

Now mostly got the car together and me and my son trying to start it and the response is not even a crank, dash are all lid up and engine failure appears on the dash. Atempted to hook OBD2 to view error code and failed to connect. Tried two different code reader and both failed to connect. All fuses are good and battery is over 12 volts, no help from battery charger in start mode.

I need idea what can cause this mode on Boxster, looks like security related?

Thanks in advance.
XR

As you were informed on another website, you are using the car's original keys with a new DME, which has the codes from the 3.2 car's keys programed into it, and the car will not start. So either install the ignition and keys from the 3.2 car, or flat bed the car to a dealer, and get ready to spend money for new keys, and programming.
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Old 05-11-2018, 08:51 AM   #4
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Hi Meir,

Thanks for your quick response, I will override the clutch switch just to make sure.

Ohhh additional information, so after we found we have no crank start and thinking the new computer not talking to the existing system we went to install the old computer and the same behavior from the car, also no OBD2 communication, crap!

Im still puzzle why my OBD2 not connecting, this is some what unexpected. I was hoping that port will provide me with the error code I can start addressing issues.

I need OBD2 get sorted out first.

Thanks,
XR
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Old 05-11-2018, 08:58 AM   #5
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Hi JFP,

My key is currently battery dead, Im not getting the flashing red light during the locking and unlocking.

I will buy a new key battery today and try it on my old ECU, Im thinking I should be able to start my car using the old ECU. The car may not run right but it should start.

Thanks,
XR
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Old 05-11-2018, 11:57 AM   #6
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New Key battery did not help, still flashing red light on my key.
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Old 05-11-2018, 12:36 PM   #7
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Have you checked your fuses?
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Old 05-11-2018, 01:23 PM   #8
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Quote:
Originally Posted by xr_guys View Post
New Key battery did not help, still flashing red light on my key.
Just a note: The battery in the key has NOTHING to do with starting the car. The parts of the key that effect starting the car are the blade (to turn the lock for the ignition switch) and the transponder (to send the correct code to the immobilizer)
Here's a pic of the transponder:

That's the only thing needed inside the key to have the car start. No battery, or electronics.
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Old 05-11-2018, 01:44 PM   #9
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...
we went to install the old computer and the same behavior from the car, also no OBD2 communication ...
Make sure that all of the original 2002 elements are in place: Key with transponder, immobilizer box, and DME (ECU).

Ground not correct? Big ground wire in the engine compartment. Bundle of brown wires in the trunk by the DME (ECU), brown wire that bolts to the floor by the immobilizer box under the seat.

Is the starter known good?

Is there more to the story? Could the car crank before you started on the engine swap...?
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Old 05-11-2018, 04:13 PM   #10
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Will a 2002 DME (7.2) start a 2003 (7.8) engine ???

If not, then you'll have to get the 2002 transponder and immobilizer reprogrammed to match the 2003 DME.
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Last edited by thstone; 05-11-2018 at 04:23 PM.
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Old 05-11-2018, 07:17 PM   #11
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Not a whole lot to add other than my cheap OBD reader will not communicate with my 2000S unless I start the car, which of course, you can't do. The OBD reader had similar issue on a BMW we owned but would work just fine with our 350Z and 4Runners
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Old 05-11-2018, 08:40 PM   #12
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Have you checked your fuses?
Yes we have, all of them are good.
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Old 05-12-2018, 04:09 AM   #13
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2002 versus 2003 differences:

Wiring harness
Software

I'd not be surprised if that's the problem.
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Last edited by Jamesp; 05-12-2018 at 04:28 AM.
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Old 05-12-2018, 12:08 PM   #14
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Hi 78F350,

Thanks for your reply, yes I saw the little pill inside the key, then I realized that was a transponder of sort.

The car ran before the swap, off course using the old engine. I was expecting when I returned the old ECU will resolve any security.

Thanks,
XR
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Old 05-16-2018, 08:34 AM   #15
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OK latest work and still no crank or start. Also OBD2 not communicating.

New battery
Check fuel pressure bypass relay, good pressure
Check clutch switch
Reconnect immobilizer module
Disconnect radio fuse, maybe K & L lines interfering with after market radio

Currently the car top partially open or some people called service mode.

Im starting to believed my key pill could be bad?

I still need to bypass the starter relay to temporarily crank the car to make sure that connection is good, whats the best way?

Thanks,
XR
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Old 05-16-2018, 08:53 AM   #16
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Quote:
Originally Posted by xr_guys View Post
... 2002 Boxster S ... Replaced the engine with a 2003 model Boxster S ... Following the Pelican Engine swap advice. Looks like I need to upgrade my ECU to 7.8 from 7.2. I got one from Ebay ... Only modification I did to the wiring is the transmission back up light connector from 5 speed to 6 speed.
ok, so perhaps you didn't follow the pelican advise completely? they state that you have to modify the dme pinouts slightly; it appears you only modified for the difference in transmission (was the new ecu for a manual or a tip, as that needs to be coded in as well if i recall correctly). you might find that some pins have to be moved around. i suggest you get the dme schematic/pinouts for both a 2002 and a 2003, make an excel spreadsheet and compare the two. go on ebay and get a set of pin removal tools from china for $1.99 and move what you have to move. i'm thinking some of the CANbus wires have moved, and perhaps the k-line (obd signal).
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Old 05-17-2018, 03:26 PM   #17
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Following the Pelican engine swap instruction the two 7.8 Motronic from 02 996 and 07 Cayman wiring are still different from each other, since i have a 2002 S body with 2003 S engine which 7.8 should i follow?

Donor Engine 2003 S Auto
Donor Wiring 2003 2.7 Manual
Donor ECU Module 996.618.604.00 (i think its for 7.8)

I have xls sheet that i'm putting together, need more detail to complete

Thanks,
XR
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Old 05-17-2018, 04:09 PM   #18
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at this point, perhaps just confirm that the dme has power and see if you can pull an obd signal direct from the unit. here's what i have for 2002 pinouts for that connector:

Connector I, 9-pole
Pin Designation Pin Designation
1 Terminal 15 - switched power
2 Terminal 30 - always on power
3 W-wire - OBD
4 Ground, electronics
5 Ground, fuel injectors
6 Ground, output stages
7 Throttle motor actuator
8 DME relay terminal 87 - pretty sure this is permission from immobiliser to turn on
9 Throttle motor actuator

Last edited by The Radium King; 05-18-2018 at 01:37 PM. Reason: just to note that these are for a 2002 996, not 986 ...
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Old 05-17-2018, 08:12 PM   #19
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King,

Looks like base on the internet information 7.2 DME should have below

Connector 1
1.Terminal 15
2.Not used
3.W-wire
4.GND Electronic
5.GND Injections
6.GND Final Stage
7.Terminal 30
8.TERM.87 MFI-DI
9.Not used

I need to move the female line #7 (Terminal 30) connector 1 to pin #2 to match 7.8 DME.

Not what tool can i use to extract the femal pin from the connector housing?

Thanks,
XR
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Old 05-18-2018, 11:37 AM   #20
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https://www.ebay.com/itm/11Pcs-Car-Wire-Terminal-Removal-Tool-Wiring-connector-Pin-Extractor-Puller-Tools/382191260228?epid=12012656784&hash=item58fc5fd244:g:MzUAAOSw74VZjHYh

and double check your info; 5v at the wrong place can cause troubles.
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