16v into 85.5 woes, no spark, no tach bounce, starting to lose my mind...

[Fraser_Crenshaw]

Figured I'd see what you guys have to say about my no spark 16v swap. I've done a ton of troubleshooting since I first started battling this...

Car is an 85.5 NA 8v, in which I swapped an '87 16v motor, harness, flywheel, ecu, ICM.

No Spark, no tach bounce. It seems that the ECU is not sending any signal to the ICM to drive the coil. I can fire the coil via the ICM manually by grounding out the pin 1 on the 14 pin connector by brake booster.

Reference sensor tests good, and I have swapped in a known good one from my 8v just for grins with no change. It was gapped too high initially, manual calls for >3v AC while cranking- it was more like 2.2v, after gapping it jumped to like 7.xx volts. This is at the stock .8mm gap specified in the manual. Not totally sure what that means. I do have a new reference sensor on order that will be here in a couple days just to completely rule it out. I also have a new ICM on order, though by all counts it seems to be functioning as it should.

ECU is firing the injector harness- I take this as another indicator that the ECU is receiving the proper information from the reference sensor, but maybe I'm wrong. Injector harness stops firing with the reference sensor unplugged.

All this pointed me in the direction of a bad ECU. I tried another secondhand ECU today, no change. There obviously is a possibility that they're both bad but I pretty well doubt it.

Any ideas here?

[Jfrahm]

Possibly alarm wiring or Ignitor (ignition module).

https://members.rennlist.com/tholyoak/944_engine_swap_wiring.htm

944s2 3,0 engine wiring

[Dan Himan]

Dme relay?

[Fraser_Crenshaw]

Originally Posted by Jfrahm

Possibly alarm wiring or Ignitor (ignition module).

https://members.rennlist.com/tholyoak/944_engine_swap_wiring.htm

944s2 3,0 engine wiring

I'm assuming the alarm wiring is good, as it was running with the old 8v motor no problem prior to the engine swap. Also I think the ICM is good as I can get it to fire the coil if I ground the output from the ecu to it manually.

Those links have proven exceptionally helpful, especially as I was confused about the ICM wiring.

[Fraser_Crenshaw]

Originally Posted by Dan Himan

Dme relay?

I've got one of the F9T solid state relays in there that was working great with the old motor, not sure if they even really fail, maybe I'll toss a spare I have in there just for giggles...

[Jfrahm]

DME relay shouldn't be a factor if the DME is lit and the fuel pump runs. But a jumper wire alternative is nice for troubleshooting when nothing seems to make sense.

Alarm wiring is in play if there is a need to jumper pins or connect the S2 DME to the alarm brain to satisfy the disabler, I do not recall the details of this but I have a shiny nickel that says it's different from an 8V.

-Joel.

[PHillary]

Originally Posted by Fraser_Crenshaw

I'm assuming the alarm wiring is good, as it was running with the old 8v motor no problem prior to the engine swap. Also I think the ICM is good as I can get it to fire the coil if I ground the output from the ecu to it manually.

Those links have proven exceptionally helpful, especially as I was confused about the ICM wiring.

+1 on alarm jumper/bypass...My 16V S model will crank and crank but no start if the alarm isn't constantly jumped just stuck two wires in the correct slots taped them down and she starts up every time...Just do it anyway to rule the alarm out.

[Fraser_Crenshaw]

Originally Posted by PHillary

+1 on alarm jumper/bypass...My 16V S model will crank and crank but no start if the alarm isn't constantly jumped just stuck two wires in the correct slots taped them down and she starts up every time...Just do it anyway to rule the alarm out.

It appears that the existing alarm harness jumpers are correct, unless they need to be jumpered differently to jive with the 16v ECU/harness?

[Fraser_Crenshaw]

Can anyone confirm the actual activity during cranking (or running, for that matter) at the ecu pin 1/pin 1 at 14 pin connector? (ignition pulse to final stage) I'm just assuming it's a pulsed ground to fire the ignitor but I don't know for sure what to look for....

[Fraser_Crenshaw]

Holy frickin smokes, it lives. Turned out to be a bad ICM. Wish I hadn't troubleshooted the entire system for a week....

Now to find out why it sounds like I have no oil pressure in the top end....