Y8 swap into 91 SI - Engine not cranking

[hebelowkey]

Let me get the background info out of the way...
I had a cracked piston in my A6 and instead of rebuilding it I got a Y8 from my buddy that only has 6500 miles on it but has been stored for 6 years. In the interest of keeping the swap simple and because I'm NOT trying to build it up (now or ever) I used everything from the A6 except the block, head (and internals) and exhaust manifold.

I have carefully transferred the tranny, intake mani, dizzy, alternator and etc... over and transferred the 4g harness to the new motor. I have made only the following changes to the 4g harness: extended the radiator fan switch wires to the new location on the thermostat, extended the O2 sensor wire for the different location on the Y8. Per "Mechanic B's" (and multiple other sources) directions I have not hooked up the crank fluctuation sensor, knock sensor, or oil pressure sensor (located at the VTEC housing)

That being said, all wiring from the 4G harness has been accounted for (no extra plugs) and the stock 4G ecu should be able to find everything it needs and nothing extra.

The VTEC controller is an external RPM activated switch and relay (which shouldn't have any affect on the whether the car starts or not - and that is my problem).

With everything back together (including fluids and a good battery) the engine was not cranking. I can hear all the normal sounds from the fuel pump to the starter engaging the flywheel but alas, it does not turn over. I had Autozone test my starter (good) but tried a new one anyway which produced the same results. I unhooked, checked and rechecked all my connections, put it back together again and then it would crank (but not run) when I tried to start it. I would expect some trouble for an engine that sat for that long. I checked to make sure it wasn't seized by turning the motor over by hand and that was fine. I thought that I was making progress because at least now it was cranking and then for no reason it stopped cranking and doing what it was doing before. I checked the battery and all wiring again and still nothing.

The very first time I tried to start it after the swap I had the starter from the y8 in but switched it out for the old one after a quick check revealed that they were different starters. Could this have damaged something? What and how would I check it.

Does anyone know what's up? It seems too coincidental that a clutch safety switch would be faulty that started at the exact time that I swap a motor.
Something has got to be faulting something somewhere right? No bad fuses, the main relay appears to be functioning.
The very first time I tried to start it after the swap I had the starter from the y8 in but switched it out for the old one after a quick check revealed that they were different starters. Could this have damaged something? What and how would I check it?

[efrue57]

....

[hebelowkey]

The A6 inujectors. Would that have an effect on the engine not cranking? I have checked for fuel and spark (during the time that it was cranking and not starting)

[isl_cruiser]

So you have power to everything, but she just wont turn at all. Like the motor wont try and crank??? Do you have any wiring diagrams? You should follow your started signal wire from your ecu to your main relay, check it there and then out to your starter aswell. I'm having almost the same problom with my MPFI 1.6L swap on my dx. More chasing instore for tommoro!! If you dont have a diagram I can save one and send it to you tommoro at school.

Let us know how it goes. Mebay were having the same problom and fixing one leads to another

[hebelowkey]

Thanks for the reply.
I've about had it with troubleshooting and wire tracing. I am going to give it one more try before getting it the hell out of my garage. I don't have a schematic. I must have done something because the car was even running with a pencil sized hole in one of the pistons before I did the swap. I know it's something phucking small because I have checked voltages all over the place and it "seems" to be fine.
With the key in the on position, if I jump the starter terminal to the battery it still doesn't crank.

[efrue57]

....

[killakam666]

check the firing order!

[efrue57]

....

[efrue57]

....

[sdlEF]

one thing you might of notice is the y8 block has a crank sensor behind the crank pulley. is that plugged in? A6 had the crank sensor inside the dizzy. "no crank sensor no start"

[hebelowkey]

Thanks for all of the input guys, I appreciate you taking the time to help me out.

Today I wanted to try push starting it but thought that it might need a little more than a little push...

We hooked it up behind my truck and began to pull it down the block (quite a site I'm sure). It took a full second or two after I put it in gear and it started and ran great.

After a quick cruise to allow the engine to warm up I shut it off in the drive. A few moments later I tried a key start and the same thing happened.

A few tries later it started from the key. I figure the starter hasn't gone out yet but is on its way out which would explain why the Autozone test passed. If I give it a little tap while someone else turns the key it will work.

I guess it was just coincidental that it started getting bad then.

Does anyone know why the starter from a 6g EX wouldn't work? I know the replacement parts have different part numbers but if I can avoid buying a used one by putting the 6g starter on that would be great.

[sdlEF]

my only guess would be the starter design or tranny case being different so trying a diff starter from another gen wouldnt line up.