964 ignition problems stumped
 

Hi guys I don't know if anyone can help with this but my 964 motor only runs on one side ignition module and coil, motor will start and run on one wiring harness plug to module but will backfire and shutdown when trying to run on other module alone:( I replaced the igniter {ignition module} and no different, checked harness with ohm meter all wires checked out from ECM to connector plugs, If I switch connector plugs to other module and coil then that side works :confused: I thought motor should run on either side of module, wondering about my Dme ECU, The motor will run with both modules plugged in however down 45-50 hp, checked resonance valve flapper;and WOT switch, idle micro switch, distributers, rotors, running out of ideas,
thanks Bob

Seems like that's your smoking gun; you need to check the wiring upstream of that point since obviously everything downstream of that connection functions when connected to the known-good control harness.

Do you know which one on the dual dsitributor is the igniter connected to that will start and run? There is a primary and secondary on the twin dizzy. Did you check the dizzy belt?

either one connector that works is secondary, hook it up to primary now that side works!

yes distributer belt checked

Sorry for the confusion plug that works is the primary, could the DME computer cause this? I think primary and secondary wires should connect somewhere in harness so still looking.

Thanks so much SmileWavy that figures found 2 hall sensor wires disconnected repaired them but apparently still not working. Bob

The DME ECM provides just one output for both ignition modules.
A Hall sensor problem will not affect the spark signal output to either
coil. Again, there's the just one spark signal output.

You need to run one set of spark plugs at a time to determine the problem.
Start by getting one set to run and then switch the connector from the non-running
set, i.e. at the ignition module. If it again runs, the wiring from the DME ECM
is O.K. Use this procedure to eliminate good components from the non-running set
of spark plugs.

we have done that checked each side ,1 ignition module plug the primary side works engine runs when plugged into either module primary and secondary. what happened to the post from RSSCOTTY ??said he had same issue :confused: he said bad hall sensor ,changed dizzy and problem fixed
Bob

Problem found :) bad connection at igniter plug thanks for the help porterdog Bob

I'm having the same problem. When you say it was a problem in the plug, can you give any details?

http://forums.pelicanparts.com/porsche-964-993-technical-forum/956700-ignition-woes-runs-top-bottom-but-not-both.html