S52 OBD1 no start...been working for 10k miles until now?!

[Slovik]

Cam position sensor can often times cause a no start or a very very poor idle at 100 rpm or so. gkurey, Being as you are OBD1 why not get Carsoft so you can just read the codes, I've had it for 10 or more years and it work pretty good even on some OBD2 BMW up to 1998.

[gkurey]

Hey guys, thanks for the input. Slovik, my cam sensor is working OK, at least the resistance is in spec.

I've made some good progress this week so far. Last I posted, I wasn't getting indications of a functioning DME without jumping the main relay...replaced the relay and the same conditions persisted. I checked all the wiring, had voltage where I needed it at the right level so I assumed the DME wasn't using the voltage it was getting ---> ordered new DME.

I got the new DME yesterday...plugged it in with high hopes, and you guessed it...no change, same indications; no CEL, no ICV hum, no nothing. I began to get even more frustrated. I HATE throwing money at problems to see if things work or not, and even more so when it doesn't pan out (who wouldn't?). So, how could it be that with voltage in all the right places that two ecus don't work, two main relays don't click...something wasn't adding up...

I did a little reading up online about electrical troubleshooting, and found a few references that stated just because you have voltage and continuity with a DMM doesn't mean the wire can carry current. This made sense, and sounded like something I was experiencing. So I wanted to see if the DME was actually getting current. I used a test light to check ignition power to the DME...and with 12.1V, couldn't illuminate a little ol' light bulb. I was on to something. I began to check the wire connector to connector to look for my current drop, working backward from the DME. I made it to the adapter I mentioned a few posts ago, the one I got from a forum member on here for my swap...there was some shady wiring in there. I got good current before the adapter, but not after. Given the overall workmanship, I decided I needed to do away with the adapter and hard wire the s50 harness right into a c101 plug to bypass bad wiring I have no confidence in anymore. In the mean time, I used a test wire from the ignition wire at the body side c101 to the DME ign pin, and boom, DME powered on.

So finally I was back to where I started...no spark, have fuel, have good DME indications, but no start.

I decided with good continuity, good volts, and good results with test light, power was definitely making it to the coil, so I became suspect of the grounds for the coil. This led me on a wild chase and I'm still coming to the same conclusion, my grounds seem good. Just to be sure, I polished up the leads to each grounding strap on the 1 & 6 coils to ensure a good connection.

Still nothing...I was still a little suspicious of the power output of the ignition and I started looking inside the car...I rattled around the few bundles of wire under the dash, and tried again....I got a sputter!!!

A few more tries and I got it to start. Being as I had a shady ignition wire not powering up the DME, I decided to rewire my harness like I mentioned above, and go straight to the c101....I got done doing that and when I was done...fired right up! I think I was mostly having an issue with poor wiring quality.

So as I wind down and start putting things back together, I decide to go take it for a test drive. Key in, turn key, and no start...only crank. WTF! Not this again....

I tapped the bundle of wires under the dash again for grins, and I get the thing to start up again. I definitely have something going on under the dash...thats for sure!

If anyone has any ideas, I'm all ears. Looks like I'll most likely be checking each connection carefully to make sure everything is seated tightly tomorrow....

WHAT A HEADACHE this has been! Thanks for the support though, fellas...I'll keep it updated.

[Adrian_Visser]

Nice work man! It's a good feeling when you track something down like that isn't it? Well you know where it is now, could be a wire broken inside the insulation could be right at the ignition switch maybe?

I would suggest checking the connection at ignition switch itself then if no change just running a new wire from the ignition switch to the c101, make sure it's the same gauge wire.

EDIT: Everything I've read about cam sensors indicates that the only way to cause a no start or shitty stumbling idle is by swapping the cam sensor and crank sensor connectors on the harness which is only possible on a NV.

[gkurey]

My biggest pet peeve is when you find a thread pertaining to a problem you have but there being no solution. I stumbled upon this old thread and thought I should post my resolution:

I sorta left this one hanging open-ended but I was able to get it all going reliably again within a day or two of the last post. Between rewiring my C101 and also replacing my ignition wire (big green, under dash) I was able to get it starting every time! Thanks for all the help, r3v rocks!

[20gmr]

does your car have a 13 button obc? could quite possibly be the obc relay. Just this week I replaced one on a car with similar symptoms

[JRKOUPE]

that was a good read...thanks....and thanks for the conclusion!!!

I have an s50 obd 1 swap as well....and I have about the same problem.....

car runs for many( 200) miles or so.....several days........then she just dies during idle, oR whIle cruising, and then wont start...

Ive thrown 2 new crank sensors at her.....she then started.....then days later died..or no start.......no fuel or spark.

Im lost....

[gkurey]

Check that green ignition wire...and even if it has voltage on it, it may not be carrying current, so I would look into that. Check for ECU power via CEL when you key up...let me know. I feel your pain...