Hey guys,
So as the title states, I’m getting a no start on my obd1 s50. The chassis is an 87’ 325is.
I did the swap initially back in 2015, and it ran without issue until the fuse for my 16” spal pusher went out, and I didn’t notice till the headgasket and presumably the head bit the dust. I removed the intake manifold, wiring harness, and cooling system, labeling everything, and the car sat for about a month or two until I was ready to swap in a rebuilt S50 that I sourced. The reason I went with the new S50 instead of rebuilding the old one, is that I hydrolocked the old one really bad.
Long story short, I got everything swapped in and set up to get a first start and bleed the coolant, but when I went to start the car, it cranked and turned over twice or three times, and then I was met with a loud click from the starter. I don’t remember if the cel came on with the key in the on position the first time it cranked, but I never got a cel with the key on after that. I labeled everything as I took it apart initially, so I don’t think I mixed up any connections.
When I started to diagnose, I started to continuity check random things with a multi meter to make sure it wasn’t just the engine ground or something simple like that. This is where things start to get very strange- I got continuity between the +12v pole in the engine bay, and the ground on the shock tower. Absolutely stumped, I pulled the intake manifold to check connections and found that if I removed either the signal wire to the starter, or the wire connecting the alternator to the +12v at the starter, I would lose continuity between the positive terminal in the engine bay and the shock tower. Absolutely stumped, I unplugged the ecu and continued continuity testing, and found that with the ecu unplugged, and with all wires to the starter and alternator hooked up as they should be, I would lose continuity between the +12v in the engine bay and any ground source in the engine bay.
At this point I’m very confused, I’ve ordered another 413 red label dme from eBay to try, but it just dosent really seem likely that the ecu would be fried, because the car was running just fine before I blew the headgasket. What makes me suspect the ecu, is the lack of a cel with the key in the on position. I thought I could have mixed a ground and +12 in the harness but I’ve double and triple checked, and everything is setup as it was before.
One thing- the starter would occasionally stick, or click, and I would have to turn the key a few times to get the engine to turn over. This is actually what led me to hydrolock the engine; I confused the fact that the cylinders were full of coolant with the intermittent starter issues, and continued to turn the engine over until it fired. Stupid mistake I know..
Anyways, thanks guys, any ideas would be much appreciated.
Cliffs: No cel with key in on position, continuity between +12v in engine bay and ground source in engine bay with the ecu plugged in, possible lingering starter solenoid issue
So as the title states, I’m getting a no start on my obd1 s50. The chassis is an 87’ 325is.
I did the swap initially back in 2015, and it ran without issue until the fuse for my 16” spal pusher went out, and I didn’t notice till the headgasket and presumably the head bit the dust. I removed the intake manifold, wiring harness, and cooling system, labeling everything, and the car sat for about a month or two until I was ready to swap in a rebuilt S50 that I sourced. The reason I went with the new S50 instead of rebuilding the old one, is that I hydrolocked the old one really bad.
Long story short, I got everything swapped in and set up to get a first start and bleed the coolant, but when I went to start the car, it cranked and turned over twice or three times, and then I was met with a loud click from the starter. I don’t remember if the cel came on with the key in the on position the first time it cranked, but I never got a cel with the key on after that. I labeled everything as I took it apart initially, so I don’t think I mixed up any connections.
When I started to diagnose, I started to continuity check random things with a multi meter to make sure it wasn’t just the engine ground or something simple like that. This is where things start to get very strange- I got continuity between the +12v pole in the engine bay, and the ground on the shock tower. Absolutely stumped, I pulled the intake manifold to check connections and found that if I removed either the signal wire to the starter, or the wire connecting the alternator to the +12v at the starter, I would lose continuity between the positive terminal in the engine bay and the shock tower. Absolutely stumped, I unplugged the ecu and continued continuity testing, and found that with the ecu unplugged, and with all wires to the starter and alternator hooked up as they should be, I would lose continuity between the +12v in the engine bay and any ground source in the engine bay.
At this point I’m very confused, I’ve ordered another 413 red label dme from eBay to try, but it just dosent really seem likely that the ecu would be fried, because the car was running just fine before I blew the headgasket. What makes me suspect the ecu, is the lack of a cel with the key in the on position. I thought I could have mixed a ground and +12 in the harness but I’ve double and triple checked, and everything is setup as it was before.
One thing- the starter would occasionally stick, or click, and I would have to turn the key a few times to get the engine to turn over. This is actually what led me to hydrolock the engine; I confused the fact that the cylinders were full of coolant with the intermittent starter issues, and continued to turn the engine over until it fired. Stupid mistake I know..
Anyways, thanks guys, any ideas would be much appreciated.
Cliffs: No cel with key in on position, continuity between +12v in engine bay and ground source in engine bay with the ecu plugged in, possible lingering starter solenoid issue
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