No spark at coil (W201)

[alas]

I have other posts in regard to my '89 190E 2.6 that shuts down after 10 to 15 minutes of operation, most recent check was power to coil, verified with voltmeter reading about 12 -13 volts across the two studs with ignition turned on. However, I still don't have a spark during normal crank. With the ohmmeter, 2 to 3 ohms was obtained across the two studs, apprx. 9000 ohms when checked between either stud and the center high tension terminal. I checked the crank position sensor, it looks intact and read about 900 ohms with both ends disconnected and reading gotten at the plug end off of the EZL. Is there any other method to check the crank position sensor?
Desperately needing help.

[tower]

Different car, but same time frame. 89 volvo 240.

The ignition control system (bosch, type ?) incorporated the crank sensor to tell the computer where the crank was at any particular time. All fed to the computer, which controlled the spark by grounding the coil ground lead. Not directly though. The system incorporated a "power stage", nothing more than a power transistor in a housing so that the large currents needed by the coil didn't pass through the computer, kind of like a relay. The important point is that the power stage connected the coil to ground when the spark was needed, coil always had 12v feeding it.

I guess what I'm trying to tell you is you need to research the "whole" ignition system to understand how it works. This is just a condensed version of how the above Volvo's ignition worked, and may not be appropriate for your vehicle (personally, I've never seen or worked on your vehicle). At this time you are trying the "blue car" fix so you have to go back to the drawing board, get a grasp of the ignition system and then back check.

Originally I pointed you to a past experience with the crank sensor because I had that problem personally happen.

Some more experiences on a 1988 volvo. The computer is controlled via a seperate fused link NOT in the fuse block. Just a fused holder connected to the sidewall of the vehicle. The holder attachment in one case broke having the whole fuse & holder fall under the battery, unseen, bouncing around at random. Car symptoms where spurious, it would run and then spuriously stall and not start. No unusual warning lights illuminated. Subsequently twisting coil wires/ignition feed wires would unintentionally move the fuse holder (unseen) so that the fuse made contact and the car would run...until the next bump dislodged the fuse. I only found it by tracing each component of the ignition circuit from the battery and probing with a voltmeter to find where the break in the circuit was.

Do the research man...exactly what does the ignition system look/respond like and then chose the appropriate test points.

Concerning the crank sensor, its function is to tell the computer where the crank is at a given period of the cranks turning. So it sends a pulse at each rpm or multiple to the computer to tell it "Okay, crank just past this point, get ready to fire" so an ohm reading doesn't test the sensor. You need to see or test it with the engine turning to see if it is generating the pulse(s). What's involved may require a scope or more in depth testing equipment as the voltage/duration will be very low/short, maybe not within a voltmeter's capabilities.

Best I can do for you. If it appears like I'm berating, I am not.

Good luck

Ron

[psfred]

Does the voltage on the low voltage side "switch" when you have no spark? That is, if you hook up a VOM, does it ocsillate between 0 and 12 v? If so, the coil is bad, if not, you have no signal to the EZL or the EZL itself is bad or has a wiring problem.

Peter