91 no spark again.
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Tuned
Joined: Mar 2005
Posts: 373
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From: Calgary
91 no spark again.
Hi there, thought I had this licked last month but motor died again. Good fuel, good cranking RPM, 5-9mV @ EDIS pins 5+6, no spark. Got a code 18 so no tach output to PCM, tach doesn't bounce when cranking either. Tried a different module no luck. Are there any places these harnesses rub thru or notorious connections to look for? All ideas cheerfully accepted, Iain.
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Joined: Jan 2004
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From: Pauline, South Carolina
How about the crankshaft sensor? If it's bad the tach wouldn't get a signal. Also, on my '92, I had a problem with a loose wire in the ignition module plug once. It would come and go with a no spark condition when cranking, but if the engine ever started, it would run like a top. Took a long time to find that problem.
Posting Guru
Joined: May 2002
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From: Phoenix
Since the ignition control module is in front of the battery and the harness directly beneath the battery, there is a prime location for corroded wires. Did you change the coil last time? I can't remember the solution.
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Tuned
Joined: Mar 2005
Posts: 373
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From: Calgary
Yes I had a spare coil, module, vrs, pcm. What made no sense was I changed the BAP as a hail mary and it fired right up. It died 3 weeks later on the road so I plugged in the spare again and away we went. When everything is normal, the engine will run without a BAP but it leaves the CEL on full-time. It fired up for me again yesterday and we went for a cruise everything was fine, so with it warm and idling I started tapping all the sensors. A good rap on the TPS killed it, I tried my spare and still nothing. As for spark,I'm using a neon spark tester between plug and wire. When engine runs you get a nice orange flash, currently you see a weak blue spark in the bulb. Is there a knock sensor on this engine and if it goofed up can it kill the spark?
Good tips on the module and harness guys, I peeled back the plastic loom and all appears clean. So here I sit with brain in open loop mode, please keep the ideas coming.
Good tips on the module and harness guys, I peeled back the plastic loom and all appears clean. So here I sit with brain in open loop mode, please keep the ideas coming.
Elder User
Joined: Jan 2004
Posts: 805
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From: Pauline, South Carolina
I don't think the '91 had a knock sensor, but I can't swear to that. You might try wiggling wires and see if it makes a difference. That's how I found the problem in my module plug. An engine wiring diagram from the Autozone site is located here(http://www.autozone.com/images/cds/g...3d800ba9ce.gif). It will show the various components and which wires go where. Also, in all the things I heard that you tried, I didn't notice anything regarding the crankshaft sensor.
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Tuned
Joined: Mar 2005
Posts: 373
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From: Calgary
0.5 vac at crank sensor and terminals 5+6 of edis. There is continuity between terminal 2 of edis and tach test output, no voltage signal when cranking. Does any one know what this value should be? How about signal voltages to the three ignition coils at cranking speed? I get nothing and there is continuity between coil pack and edis. Getting cold out will check continuity between edis and pcm tomorrow. EDIS has been tested twice as has my spare. The plot thickens, sure wish I had a breakout box.
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I'm with JerrySimm in thinking this is a bad crankshaft position sensor. It's accessable from under the front, right at the harmonic balancer. A dead CKP will give all those symptoms; no tach signal, etc.
One of the sensor wires should have about 1.5v on it with the key on. The other should have a pulsing voltage on it with the engine turning over (One pulse per engine revolution). An analog voltmeter set on the AC scale is best for checking this. If it's not pulsing the sensor is dead. Be careful of belts and all the rotating stuff when checking.....
TLR
One of the sensor wires should have about 1.5v on it with the key on. The other should have a pulsing voltage on it with the engine turning over (One pulse per engine revolution). An analog voltmeter set on the AC scale is best for checking this. If it's not pulsing the sensor is dead. Be careful of belts and all the rotating stuff when checking.....
TLR
