HELP! W126 Won't Start - 380SE
 

1985 380SE approx. 132,000 miles. I drive it about 2,000 miles per month, has always run like a champ for the last year. Last driven on Tuesday evening, parked it until this morning (been working from home). Got in and it just cranked and cranked and cranked but did not start, not even one hint of wanting to start. Here is what I have found so far:

Spark from the ignition coil wire
spark at plug wires
plugs are newer and still look good
plugs smell like fuel
a shot of ether down the intake plate (just to be sure) did nothing
cap & rotor about a year old and slightly worn, but nothing out of the ordinary
coil primary measures about .4 ohms (within spec)
coil secondary measures about 9 kohms (within spec)
wires relatively new
fuel pump relay about 9 months old (old one resoldered but failed again)
jumpered between FPR terminals 7 and 8 just to be sure

Even after all the above, can't get one sign of life out of it. The battery must be in excellent condition, since I have been cranking the life out of it and it is just now showing signs of slowing.

FWIW, it has been raining heavily here for the last 3 days. I initially thought this was moisture related, but not even ether can elicit a kick out of it. I am stumped for now...

Any other suggestions out there? Thanks in advance!

Bump

B U M P

spark
 

You may have spark but is it at the proper time? You may be getting to much resistance from the position sensor, give Dave a call he to is in the DFW area,and a member here 214 956 7007. But in my opinion replace it. JNT:furious2:

OK, yesterday I was poking around under the hood. Took out the OVP, removed the fuse to inspect (it was fine), and reinserted everything. Tried to start the car, but it wouldn't. Then I wiggled the small plug with the green wire going to the ignition module and noticed it wasn't seated all the way. It was on there tight, just not seated all the way (maybe plugged in about halfway). I reseated it, then checked a couple other things (can't remember which). A minute or two later, I cranked it and the engine fired right up. With the car running, I went back and wiggled the small plug again, loosening it and tightening it, etc. playing with it to see if I could get the car to stall with it partially seated. The only way I could kill the car was by completely unplugging the small plug. Having it partially seated seemed to have no effect on the running engine.

I drove the car an hour to work today, and though it ran fine, I am scared. Could this be an intermittent problem? Will I be stranded when it's time to go home? I'm not fully convinced that reseating the small plug had anything to do with the car running now. Especially since the plug seals all the way around the socket, so I can't figure out how moisture could even get in there.

Questions:

* It was raining heavily when the car was originally parked - is it possible moisture got into the plug and caused a poor connection? Yesterday was in the 80s so it's conceivable that the moisture dried out. If moisture was the cause, wouldnt' the car have run poorly or stalled before I parked it?

* Can this be a sign of the CPS going south? Should I get under there after work and take some measurements? How do I do so?

* Has anyone ever experienced this? The car was running like a champ one day, dead as a doorpost the next, then running great again as of yesterday.

What is CPS?

- Peter.

CPS = Crankshaft Position Sensor. Interestingly, though I have read that this car has one, I don't see any direct mention of where it is located and I don't see one listed for purchase in FastLane.

Replace the EZL (Ignition Control Unit) with one with the same part number and try to start the car.

The EZL is only about a year old, was replaced by the PO. It connects to the small connector with green wire that I mentioned earlier (the one that wasn't seated all the way). The small connector is the one with a single pin and is round in shape. I wonder if moisture could have gotten into this connection if the plug wasn't completely seated? Would a helping of dielectric grease hurt?

You said you had spark but it would not start.

What color was the spark?

The coil can break down and put out a weak yellow or reddish spark. It should be blue white. The weak spark will NOT start the car, even though you see a spark when you look for one.

It the coil is going bad, you may have jostled it enough to get it working when you were pulling on the green wire.

Thanks for the input - not sure if you missed it above, but I took coil measurements: coil primary measures about .4 ohms (within spec) - coil secondary measures about 9 kohms (within spec). Unless I'm mistaken, these measurements indicate that the coil is fine.

Maybe there is a little break, or corrosion inside the wire itself.

i think the single wire that you refer to goes to the pickup in the distributor.those engines did not have the pickup at the flywheel.that green wire has been known to fall apart at the distributor end and cause intermittent spark.check it out.

I have driven the car almost 200 miles now without a hitch. Though I want to remain suspicious of various electronic components under the hood, I think Occam's Razor dictates that my wiggling of the connector on the green wire has resolved the problem.

David and raymr, I will still be checking out the green wire per your suggestions, as I'd hate for a flaky wire to strand me somewhere. Thanks for the input!

But you did say you had spark when the engine wouldn't fire up. That would mean the green wire was carrying current.