Ignition module ground

[Tyler Townsley]

Originally Posted by 8upZR1

Tyler, I have done checked everything I can and it all looks great. One thing I was wondering is what about the ISS is what RPM is it simulating when it is turned all the way down on the crank setting. I am getting that it is making 1800 RPM. At least that is what my MSD says and it is usually very accurate. Could this be my problem? I can't imagine that the cranking setting would be outputting 1800 rpm. When I turn the knob to the cruise setting it is making a signal equivalent to 6500 rpm. Kinda high for cruising but if this is normall then cool. I guess I will empty the gas tank and refill with new gas, but I doubt that it would make a difference. I was wondering how you have an 88 ZR1. Isn't 90 the first year? Is your 88 a transplant or an engineering mule or something like that?

The ISS crank setting is 400 rpm. I am unfamiliar with the MSD setup you are talking about. If the the spark event is reported as 1800 rpm at start then that is what the ecm and dis thinks the engine speed is. I would think would lead to a spark event in the cyl too far in advance of valve closing and cause backfire and an inability to start. If the gas is bad it will smell different. Using the scope compare the crank sensor and cam sensor signals to that created by the simulater, they should be the same.
Where is the rpm signal taken from with the MSD? On the zr1 the dis has a pin out that goes directly to the dash tach which is why the tach reports the rpm correctly and the aldl software does not read correctly over 6350.

The story of the 88:

http://www.sirgalahad.org/tyler/prot...typesStory.doc

Tyler