Well looks like this issue came back, and bit me in the butt..
Started the car this morning, and had to head into town. No issues what so ever, car started like it always has.
Go to my first stop, started up fine, go to my second stop.. 10 min later go to start up, and the car was jumping and stuttering like ive never heard before. It would barely run without the starter helping it turn over, and stuttering and jumping all over. Instantly to me it seemed like a spark or ignition timing issue.
Had to get the car towed home today.. First time for it
Then I started my troubleshooting. First culprit was the CPS on the back of the bellhousing (fyi theres 2 CPS on this car, but the 2nd one on the front balancer is just used for TDC diagnostics thru the X11 plug, it is not connected to anything.)
I followed all the diag steps via the MB manual
http://www.startekinfo.com/StarTek/outside/12253/disc%202/program/Engine/107/M117_56/15-540.pdf
I tested the CPS using a mulitimeter first to check resistance.. ~700Ω
-Check voltage going to EZL- OK
-Check crank pulse from CPS using multimeter - All OK (looked just like the sample on pg 13 of the PDF above.
-Checked CPS insulation resistance - OK.
SO then I stopped and took a break. I noticed that with the CPS unplugged from the EZL, there was still spark coming from the coil (the engine would fire randomly, and jump about)... How would it know to fire the coil if there was no crank position feedback to the EZL..
Immediately I removed the EZL to try and test it in my 90-560sel.. And sure enough.. not even a hint of fire.. What caught me slightly off guard though was in my 420 with the CPS disconnected it would randomly fire, in my 560 with the CPS connected and disconnected, there was no hit of a spark or fire at all.. Odd I thought...
Oh and the thermal paste on the back of the EZL was toast.. so that could be the reason for the death of the EZL.
I haven't put my 560 EZL in my 420, I don't want to risk blowing it up. the 560 runs perfectly the way it is... But I have 2 420EZL's on the way.. Should be here next week.
Guys set me straight if im not mistaken, doesn't the EZL disconnect the primary side of the coil's ground to collapse the field and initiate a spark?
http://www.startekinfo.com/StarTek/outside/12253/disc%202/program/ETM/126from86.pdf
Pg 16 in the pdf or PG 108 on the sheet..
Ive dealt mainly with modern coil on plug ignition systems which is all logic controlled for firing and dwell time, so please bear with me for the questions on these older systems, just need a bit of time to get back up to speed with these older systems.
In the mean time, Im going to put my old EZL in my mill, and open her up and see inside
