89 Camry Challenging Electrical Problem

Our 89 Camry started running poor a few months back, particularly in hills (under load?). Eventually ended up in a no start condition. Mechanic said it was either igniter or distributor (coil). First replaced the coil/distributor with wrecker parts. Ran okay for a month or two, then started to happen again, but went to no start after a few days. Replaced the coil/distributor a second time - worked for a month then same thing. I just replaced coil again with a new Toyota coil and put in a replacement (used) igniter and ecu. Car started, drove about 10 mins, seemed okay though slightly rough running. Shut it off, then it wouldn't start. Since, I have managed to start it when cold, but not after warm - no spark. sometime when trying to start it, it won't fire until the ignition is turned off - almost like it's trying to run backwards? From what I can see, all sensors test out as normal. Something seems to be getting fried in the electrical circuit (coil, signal generator, igniter, or?) causing the coil to die, and it has now happened for 3 coils. I have run out of ideas. I would take it to Toyota, but there isn't one around for miles (and over a ferry). Could it be something to do with the alternator/regulator, or a sensor, or? Any ideas would be appreciated. Andrew

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Its often the case when tracing a fault, that we go off on a tangent. There is also the possibility that there is more than one fault. I would check the plug condition, and leads. Replace them if they are original. The distributor cap cann also give these faults if it is carbon-tracked. Under load the spark-gap reluctance increases (inside the combustion chamber). If there is another easier (or lower resistance) path to ground, the spark will take it. I had a faulty cap give simialr symptoms once. It took ages to suss it out.

If you are convinced the plugs, leads and cap are OK, I would then put a multimeter on volts range on the coil low-tension terminals when the engine is in the ''ON'' state but not running. It maybe the volts are lower than needed or marginal. Some igniters will stop working if the volts to them drops below 10v. This can be caused by resistance in the supply wiring/connectors to it. One test for this (apart from the mmeter) is to switch on the headlights to high and the AC/heater-blower fan to high while the engine is idling. If the engine dies, it is probable the supply volts to the ignition is low.

Ignition timing should also be checked.

Jason