Hold Me, R3V

[c0rbin9]

Diagnosis Update:

Engine wouldn't start again. Definitely a weird intermittent problem.

I checked for fuel and spark - not sure if I did it correctly, but it seems I'm not getting fuel nor spark. For spark I pulled a plug wire out, attached a spark plug, and looked for a spark while cranking. Nothing. For fuel, I removed the fuel feed line in the engine bay and cranked - no fuel coming out from the pump.

Since I have neither fuel nor spark, I'm going to check the crank position sensor. I wouldn't be surprised if it got damaged when I was messing with the pulleys/belts for the water pump since it's in that area. Also, an important note: I accidentally severed the wire for the cam position sensor when I did the water pump and repaired it by soldering. It seemed to be fine since the car ran, but I thought it was worth a mention. Regardless, my understanding is that the cam position sensor won't cause a no start.

Not really confident that I truly don't have spark.

EDIT: Crankshaft position sensor is in spec measured from the harness connector. (553 ohms)

[c0rbin9]

Car magically started. Dunno.

FWIW, the last thing I checked before it started was the ICV to see if the DME relay was energizing. It wasn't buzzing with the ignition on, which according to the troubleshooting manual I'm looking at means look at the DME relay/relay wiring.

Also CEL didn't light up like it's supposed to with ignition on, which I believe is also powered through the DME relay.

So I'm thinking DME relay? But the intermittent nature of the problem has me puzzled. Perhaps some bit of wiring to/from.

[roguetoaster]

You're right about the cam sensor, but it will cause poor running.

I think the main/DME relay is a good bet. Glad you're powering through the diagnosis.

[uturn]

If you're not getting your Christmas tree lights when you turn the key then maybe your ignition switch is going out?

[bmwman91]

It is sometimes the case that the fusible link form the battery corrodes and starts to break continuity. It is on the smaller wire that comes off of the battery's + terminal in the trunk, about 18" away. This wire is a dedicated 12V line for the DME and fuel + ignition systems. If the link opens, you get no power to the engine control system.

[c0rbin9]

^ Very possible. The fusible link is something I was jiggling around right before it decided to start.

If it happens again, I should be able to isolate the problem with my multimeter. Will update thread.

[c0rbin9]

Car didn't start again today. Jiggled fusible link and the main relay, and it started. Also the ICV doesn't buzz and the CEL doesn't turn on w/ ignition anymore, but the car still starts. So I'm confused.

[c0rbin9]

10/18/16 UPDATE:

bmwman91, you were right. It was the fusible link.

Today was the day it finally had enough and stopped starting even after the wiggly jiggly. I opened up the fusible link and found that the link was intact, but making poor connections at either end. Some electrical tape fixed the problem for now, I'll probably resolder the ends and heatshrink the whole thing when I get home.

Thanks for the support to all in this thread.

[c0rbin9]

Back to original problem w/ cooling system -

I'm scurred. Coolant level rises like 2 inches if I loosen the bleeder screw after driving. After pressure is released, if I turn the car on from cold and rev it, it goes back down 2 inches.