Fixed it! Super slow crank, not consistent. *update electrical trouble*

[ZekeTheSneak]

So i have my s52 swap damn near completed and I'm having some issues. When i turn it over it gets a few quicks cranks then slows down. It will backfire from to time as well. Whats going on with the slow crank? I'm going to be checking the starter, alt and the 12v leads as well. S52 getrag 260 with matching xlutch flywheel and starter. Yes dme and engine is grounded throufh the motor mount

Thanks guys

*Update electrical nightmare*

Well new information. New battery. I pulled the intake and cleaned my grounds and starter connections. Pulled the main relay so i could crank it without fuel going everywhere. I crank it and everything is awesome. So i bolt it all back together and i go to crank it, and cranks great until the cps triggers the main relay then everything bogs down. Slow crank and the dash flickering. I dont know where to start. A reputable friend did the harness for me.

[treff-7]

Did you make sure that your battery is fully charged? I guess it's been out of the car for a while due to the swap. If it isn't charged it's possible that while you crank the voltage falls too much and it's not enough for the dme to function properly or at all.

[Wishno87]

Had the same issue with a low battery.

[ZekeTheSneak]

Well new information. New battery. I pulled the intake and cleaned my grounds and starter connections. Pulled the main relay so i could crank it without fuel going everywhere. I crank it and everything is awesome. So i bolt it all back together and i go to crank it, and cranks great until the cps triggers the main relay then everything bogs down. Slow crank and the dash flickering. I dont know where to start. A reputable friend did the harness for me.

[20gmr]

any chance anyone messed with the timing of this engine? That sounds like its out of time too me.

[treff-7]

sounds like you have a major short somewhere if it slows down the starter that much. I'd say crank it while someone is checking the cables in the harness if any of them is heating up. when i did my swap i accidentally put one of the ground cables on positive. the wire started smoking but fortunately it didn't kill anything. be careful though and don't fry anything! including yourself! maybe it's a good idea to do this with the dme unplugged. i think it should still crank but i'm not sure it the relay will close...

[ZekeTheSneak]

any chance anyone messed with the timing of this engine? That sounds like its out of time too me.

Yah Its been rebuilt by Castros a year ago or so. I bought it from a fellow member. I'm looking into this as well. I haven't found anything that shows all of the timing marks just yet. Damn vanos. FML

[treff-7]

I reread your post and I'm on the wrong track.
Is it obd 1 or 2?

[ZekeTheSneak]

OBD1, I got it fingered out. The s52 had been "converted" to obd1 but someone put a nv harmonic balancer on. I switched to my known vanos one and it fired right up. Fuck yah.

[treff-7]

What a sneaky move! How the heck did they run it with that HB?
Good job figuring it out!

[ZekeTheSneak]

Well I bought an m50 vanos before the s52 to get all of the sensors and harness what have you so thankfully I had doubles of everything. When I bought my S52 it had been rebuilt and converted to obd1. It came with a market motorworks harness the whole nine. Well come to find out the 87 harness wouldn't work on my 91 so I used my spare harness. Then some sensors broke and I have spares as well. I assumed the harmonic balancer was swapped but I started checking it and noticed the Dead mark was in a different spot. I then got on here and found a few threads saying the m50vanos to the s52 all used the same harmonic balancer. So I swapped on my known correct one an sure as shit it fired up. What confuses me is how it ended up with a m50nv one on it. I believe the harmonic balancer gives timing a reference mark as well, that is why my engine was preigniting and stopping the crank.