On my other most recent post I have detailed my woes of doing too many things at once and the problems I'm facing. My main problem now is starting. What I have discovered is that I don't have spark when the key is in the start position but when the key goes back to run, the spark returns. In other words, while cranking the starter, there is no spark but as soon as you let go of the key, the spark fires and it will start. I have 12 volts at all times at the coil black wire so I know the relay is working. Any ideas?

 

you check ignition switch?

 

Jim,
Since I have 12V at the coil in both positions of the key I figured the ignition switch was ok. Schematics show the "+" line from the coil going to pin one of the DME. Seems to me that something is not completing the circuit while in the start position.

 

I've been doing some more digging on the List here and have found out that voltage on both sides of the primary coil should be about 12V. Mine seems to drop to about 6V on the "+" side. This may or may not have taken out the ignition driver in the DME. I need to check/swap the coil.

 

Not sure of the reasoning here - why would the coil work OK in run mode and not start mode?

 

Just trying to eliminate problems here. I'm stumped about this. It just seems as though there is not enough voltage when the starter is cranking to produce a spark. I have checked the battery and have a charger hooked up to keep from draining too much. Still looking for advice.

 

The voltage should be +12V (or rather, battery voltage) on both sides of the coil until you start trying to run the motor, at which time one side of the coil will be pulled to ground by the DME with a pulse for each spark firing. If you try to measure that pulsing voltage with a typical voltmeter, you will likely see much less voltage than 12V. You should see the average voltage, somewhere between 12V and 0V, so 6V sounds reasonable, but may not be right.

Do you see the (approx) same electrical characterisitics on the coil while "trying to start" and after it *has* started?

 

Mike,
It occurred to me to check that last night which I will do this afternoon. I'm also going to set the key to run and jump the solenoid with a push button starter switch that I have to see if I get spark or even start to run. I do get 12V at the DME pin 4 while starting. I'm starting to think there is a short somewhere. The schematic shows a dotted line coming off the wire that feeds the starter solenoid from the switch that goes to P99. I'm not sure what that is. Voltage on the coil in the run position is 12V on both sides(car not running) but I'll start the car and measure.