So I just rebuilt the engine on my s4 n/a convertible, and after putting it back in the car I am having a crank no spark issue. I highly suspect it is an issue with the wiring from the CAS to the ECU and here’s why:
I don’t have spark to any of the spark plugs but I know they are good because I tested them on another car and they worked great.
I have fuel pressure because one of the hoses squirted fuel when I was testing the fuel system so I tightened the clamp.
After I tried starting it the first time and it didn’t work I assumed it was flooded from me cranking the engine to build oil pressure beforehand, but when I took out the plugs and cranked it, there was no fuel vapor. So that means the injectors also aren’t working.
When I crank it over the tachometer doesn’t jump and also the tach would sometimes not work randomly back when the car was still being driven.
I used my multimeter to test if I have continuity from the CAS plug to the engine harness, which I did have on both Ne1 to Ne2 and G1 to G2, and the resistance was within the spec from the Haynes manual.
I read on here that the connector between the CAS and the engine harness can be finicky and some people just hardwire it so I did that.
Next up I used my multimeter to see if I have continuity from the CAS through the engine harness to the plug that connects to the front harness, which I also did for both the G coil and the Ne coil.
so then I went to the plug that goes into the ECU and the Ne coil/hall sensor had continuity but the G one (green & blue wire on CAS) did not have continuity.
Which means that for some reason in the past 10 months that my cars been sitting in my driveway on jack-stands, the wires for just the top Hall effect sensor and only the section that’s in the front harness has some sort of damage/issue/kink. I doubt it’s rodents because all the other wires under the dash look spotless.

So my question is: what do I do next? Tear out the dash and the entire front wiring harness?

Please tell me there’s some other connector or relay or fuse I’m missing so I don’t have to do that.

 

Your fuel injectors may need cleaning. They could be clogged from when everything dried out while it sat those 10 months. Not sure about your spark issue. What method did you use to verify there is no spark?

 

Okay so I was reading another thread and I realized I checked the wrong wires from the CAS to the ecu for continuity on the ecu plug.
Checked the correct ones and continuity is good from CAS all the way to ecu.

So I’m thinking it’s either a bad CAS or an ecu issue.

Is there a way to test if the CAS is sending a signal to the ecu? I tried doing it by testing for voltage spikes from each of the two sets of wires from the CAS in the ecu plug with my multimeter. But maybe that’s not the way to do it because I got no voltage readings.