DESPARATE-NOT SURE WHAT TO TRY NEXT ?

[Bill Golasinski]

Working on 86 GN. Car starts immediately but dies immediately.
With D5 wire from ECM, Tan/black, Bypass cut, starts and runs indefinitely.
Problem is in "Switchover" from Ignition module to ECM & Chip.
With D5 connected, key on "0" volts on D5. When car starts, 5 volts
until car dies, then "0 " volts. In chasing this have replaced:
Wiring harness, ECM 5 times, Ignition module, 4-5, Chips 5.
SAME RESULT. Starts instantly. With D5 cut, runs indefinitely.
D5 connected, DIES immediately. THANK YOU IN ADVANCE FOR
ANY HELP.

 

[RmvBfrFlght]

Double check the cam sensor phasing/location.

RemoveBeforeFlight

 

[pdzz]

ESC module???

 

[Duke]

do what he says on the cam sensor. this is what it does when it off

 

[Alaskabuick]

I bought a cat that did that a couple years ago. Starts right up and then dies? Replaced Mass air flow and it ran perfect.

 

[turboclam]

Immediately after the car starts unplug the cam sensor. If it continues to run then you've found your problem.

 

[TurboBob]

I've never seen cam sensor phasing act that way. In my experience it either runs, or it doesn't.

But at this point we've tried everything else.

The MAF has been checked, swapped, and the symptom is unchanged, MAF or no MAF (backup mode). Part of the confusion along the way was a bad ECM, but we're past that now.

If the BYPASS wire is disconnected the engine will start and run. If its connected, the engine fires but dies as soon as the ECM tries to take control (asserts the BYPASS line).

Wires have been checked for shorts and opens (its a new harness anyway, so its double checked now), the ECM, chip, and ignition module have all been swapped in every permutation.

The ESC module is not related to this.

Anyone near Houston that can lend a fresh pair of eyeballs to this?

Bob

 

[Bill Golasinski]

PROBLEM SOLVED! Finally!
Some kind of "Glitch" in NEW cam sensor CAP. Replaced NEW cam sensor cap with another
NEW Cam sensor Cap. FIXED. Here is the explanation of WHY does car run with D5 cut But NOT
with D5 connected.? ANSWER IS: With D5 cut, engine running on ignition module only, injectors BATCH firing(they ALL fire @ once)
With D5 connected, injectors quit firing BECAUSE ECM is trying to control injector firing through the CAM SENSOR CAP READING, but can't
so injectors quit firing (squirting?) and car dies. What was the glitch in the cap? WHO KNOWS?
MANY THANKS to Bob Bailey who showed me how to check various components and MANY OTHERS who had GOOD SUGGESTIONS.
I have been working on this thing for almost 2 months and was about to give up.
Again, THANK YOU ALL.

 

[Ttype6]

PROBLEM SOLVED! Finally!
Some kind of "Glitch" in NEW cam sensor CAP. Replaced NEW cam sensor cap with another
NEW Cam sensor Cap. FIXED. Here is the explanation of WHY does car run with D5 cut But NOT
with D5 connected.? ANSWER IS: With D5 cut, engine running on ignition module only, injectors BATCH firing(they ALL fire @ once)
With D5 connected, injectors quit firing BECAUSE ECM is trying to control injector firing through the CAM SENSOR CAP READING, but can't
so injectors quit firing (squirting?) and car dies. What was the glitch in the cap? WHO KNOWS?
MANY THANKS to Bob Bailey who showed me how to check various components and MANY OTHERS who had GOOD SUGGESTIONS.
I have been working on this thing for almost 2 months and was about to give up.
Again, THANK YOU ALL.

This is good to know. I hope I can remember this if it happens to me.
FYI When I replaced my cam sensor years ago,it was because my motor would hiccup during a shift only. It got stupid during a rapid change in RPM. Again I'm glad to have stumbled onto this symptom. Thanks for sharing.
Too often people don't see a thread to it's conclusion so none of us get a chance to learn. Hopefully the symptom I shared will be of help to someone.