I have a 1987 944 NA chassis with a 1989 S2 engine swapped in. The engine bay and DME harnesses were both swapped over as well. I have jumpered the DME relay, bypassed the factory alarm and swapped the DME and DME relay into a running S2 to verify each worked. At this point, the car will not start. I have already tried searching the forum but it seems that no one has had a similar problem with an S2.

I have the following symptoms:

- Tach bounce while cranking
- Fuel pump does not come on when ignition is on accessory or while cranking
- No power across the coil
- Fuse 34 is good/not blown

I have verified that pin 86 on the DME relay is getting 12V+ power when cranking. I have installed a brand new fuel pump, brand new ignition control module and a new coil. I'm truly at my wits end as to what is left to check. I know it's likely that there is a wiring problem somewhere but I have no idea where to check from here. Help!

 

I'm obviously a rookie, but I'm up for a game of 'sounding board.' Any chance of swapping the computers? Definitely no spark AND no fuel?

When you jump across the DME relay, does the fuel pump run then?

Edit: Oops, I see that you've tried the DME from the running car too, not just the known good relay.

 

no spark and no fuel

 

Is the DME grounded properly?

 

+1. I once had to pay a shop $500 in labor costs because they spent a week sourcing a no start issue only to find the ground cluster near the DME was loose. Check em all while ur lookin around.

 

All grounds have been checked and rechecked.

 

What did you do about the alarm/disabler input to the DME?

 

I would double check to see if you disabled the alarm correctly.

 

I can't find anything definitive in the FSM, does anyone know if the factory alarm kills the fuel and spark? It seems that is the most likely suspect right now.

 

I was messing with my car stereo..and it had the same symptoms. I must have triggered something...I think I unplugged the battery/reattached and it started...I cant remember. It was weird as it was the only time it ever did it.

 

I've been trying to figure this out since you first posted. In the original 928, it just disables spark.

The other candidate is the airbag module, though as I understand it, that would only disable fuel.

 

Well, and that's part of the mystery. The chassis is an 87 without airbags. The S2 was a US car so it's safe to assume that it had airbags. However, I know of many airbag car owners that drive their cars with the airbag light illuminated so I find it hard to believe that the DME would cut fuel. I'm going tackle the alarm again to see if I can make any headway.

Was really hoping someone had experienced this before but it seems as though I've brought a new problem to the Rennlist brain trust.

 

Did the car run after you swapped in the S2 engine and harnesses at any point? Are you sure those harnesses are good?

 

Have you compared the schematics?
Did you make appropriate changes to the 14 pin connector by the fuse box and passenger floor?
Did you add the Fuel Injector Ballast Resistor circuit with the harness?
Did you add the Ignitor circuit part of the harness?

 

Speed & Reference sensors