tubesock

Hello everyone I swapped a 90 s2 motor into my 87 944 N/A. I did my research so I thought before swapping anything and thought I was good to go. I had the engine complete with computer and wiring harness for the engine. I knew there were some "minor" wiring changes that need to be made to wire in the ignitor for spark. I put it all toghether and got a mechanic friend that I trust to come to my house to do the wiring changes that I found off rennlist to do the swap. He wired the ignitor and we had spark but the engine would not run. On further inspection we had no power to the injectors at all (fuel pump runs) and no tach bounce. We jumpered and check and double checked. Then after more research I learned the "S" cars have a ballast resistor for the injectors that the 8 valve N/A cars do not. Well.... While im researching my mechanic is researching as well and finds by looking at the wiring diagrams from s2 to n/a that the wiring is different. He is telling me that I should have swapped in the engine bay harness from the s2 into my 87, which is a problem because I sold the donor months ago. He said that is why that the car will not run. I did tons of research on this before I started and never heard of needing the bay harness from the s2. He said after studying the wiring that he can make the nesscesary changes to the 87s harness to make the engine run along with wiring up the ballast resistors for the injectors. But before I have him do this, is this correct? I know this swap has been done several times but there really isnt alot of info on it. Any opinions? I would really like to hear from some one that has done this swap and how they did it.

Thanks

James

tubesock

Anyone got any thoughts? I'm starting to think I have a really expensive parts car now.....

MAGK944

There's probably not a lot of people who have done this swap AND who happen to be online at this time, so be prepared to wait a few days for a definitive answer.

Is this the procedure you followed: http://members.rennlist.com/tholyoak/944_engine_swap_wiring.htm

Seems like you covered everything but I'm no expert. Bump the post daily and someone will chirp in.

doabarrelroll

Yea, you need some goofy stuff like the ignition control module. On the 8 valve cars, you go directly from the coil to the harness, on the 16 valvers, you go through this control module that mounts behind the driver's side headlamp.

That link Mag posted is very helpful. I did the exact opposite of you, however, I think what you're doing is more difficult. The biggest problem I had was getting the fuel pump to run with Key On, so, with enough electrical patience, you should be able to figure it out.

ArcticSteve

I would think that the 87 needs to think it's an S2 in complete form including reference sensor, PCM, and perhaps even some main grounds. For example, the fuel pump for the S/S2 is a different part number than the 87 944.

GL

Jfrahm

The S2 motor would have to have the S2 bellhousing, sensor, flywheel etc. or it won't send the right signal to the ECU. I doubt the poster would have overlooked that.

There is also the alarm disabler pins that need to be jumpered on the S2 ECU or the ECU thinks it's not supposed to start.

tubesock

Tell me more about the alarm disabling pins..........also I did use the bellhousing from the s2

Jfrahm

I assume you used the S2 flywheel? Otherwise you have the wrong number of teeth for the crank sensor and ECU.

The alarm bypass might be more of a 968 swap issue but there is a signal line from the alarm to the ECU that needs to be maintained or the car will not start. I do think however that the wiring is different for the early S2 alarm and again for the late S2 alarm (which is more like the 968 in terms of ECU.)

https://rennlist.com/forums/924-931-...procedure.html

You might also look at the FSM wiring diagrams for the connections between the alarms and the ECU for both cars, particularly where the wires might change color at connections before going on to the ECU.

You will also want to note what wire colors are different for the harness you are using, as you are adapting the 8v harness.

Maybe start by figuring out what pins on the S2 ECU are supposed to get the signal from the alarm and see if the signal is present.

tubesock

I dropped the engine in complete didn't take the clu tch housing off or mess with any of that. What scares me is my mechanic is saying since the 8 valve computer had 35 pin and the s2 has 50 some pins that itis going to have to be rewired. But I don't see the issue since I used the s2 engine harness computer ? I have since talked to another Guy who says that I'm just missing a hot somewhere that runs the computer and to not let the other Guy start messing with jumping pins at the dme.