Steve Conar

Steve Conar here...you guys have answered me about my 1986 porsche turbo before...I have changed distributer cap, button wires and plugs and even my coil is new...I still dont always get fire from my coil to the distributer and sometimes i do (when i dont i have 12v positve but not pulsating on negative or green wire of coil)...I am down to what i believe are my last two options (short of a short in a wire of course)...figure its either the DEM or the crank sensor...is a crank sensor the same thing refered to as a reference sensor?...ps...what do you think i can do to test which one to replace first...crank sensor is much less expensive but that isnt always the way to go first...your thoughts...pss..my email is steveconar@aol.com or better yet my cell number is 423-506-9798...i am available 24/7

Ski

quick question, did you put the wires on the way they are supposed to go or, not saying you did, but people have put them on in the wrong oder.

Steve Conar

All wiring correct Ski...when I do get fire from coil the car starts and runs exceptionaly well...thats the rub...sometimes fire sends from coil just fine and the car checks out great...when it doesnt fire... i do not get a pulsed signal to ground on the coil when cranking....ps...the car has never shut down while running...the problem only occurs when restarting

Willard Bridgham 3

Could be the DME or the crank sensors. You can isolate this by replacing DME with known good or replacing both crank sensors.

hot-J

crank sensors..... Check for fraying..

ehall

+1 This is what I would look for first. If there is a frayed wire in the reference sensor lead, it will shift slightly, in place, which would explain why it doesn't happen everytime.

Steve Conar

DEM or sensors are all I can think of myself that are left to try...probably will start with the sensors and go from there...thanks all

Mark-87-951

Ditto! I just found that one of the ref. sensors I had replaced several years ago got damaged. The wire was crushed, probably when reinstalling the intake manifold at some point. I never checked because, hey they are both fairly new. Before finding that, the car would be difficult to start, but would start up and run fine with starter fluid. The tach needle moved a little but now, with a new ref. sensor it moves quite a bit more while cranking.

Tx951Dude

Freaking ref sensors. I've replaced mine once but dang if they're not bad again. When everything else has been replaced and you still have infrequent "no starts" the culprit for our cars is almost 100%, reference sensors.

ehall

If the sensor is installed to spec, it's not the sensor, but a fray in the wire...SOMEWHERE. It's not just one lead all the way to the DME. Mine frayed at the end of the lead to the DME, rather than the lead to the sensor.

Tx951Dude

Yes, but even the associated wires for the ref sensors are still part of the sensor assembly are they not?

theedge

??

The sensors have a plug on them. The usual suspect for bad wires is the car side of the plug. Wiggle the plugs and wires around CAREFULLY and see if it will start.

spyder348

DG speed-closest to firewall.
BG ref. closer to engine.
Both sensors are same pn#

ehall

Yep. Look for frays at or near the plugs. The sensors themselves usually only "fail" if they are set too close to the flywheel and get eaten up.

xsboost90

next time it doesnt start, wiggle the ref sensor plugs then try again.