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Hatchbacks Chevrolet Metro/Geo Metro Chevrolet/Geo Metro
1693 messages, Last post on Dec 05, 2009 at 7:53 PM
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Roger-Wilco-Over & Out. Thank you profusely. |
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Replying to: annielulu (May 28, 2009 11:37 pm) You can make a crude test for a shorted alternator diode by disconnecting either one of the battery cables for a minute. Then touch that cable briefly back to the battery post it was attached to. If there is a spark when it touches; there probably is a bad diode in the alternator. (but it may be normal to see a tiny spark; I'm saying that a more substantial spark means there is a bad diode.) This would gradually drain your battery overnight; unless the diode has by now been completely burned through. But even so; it still would not be fully charging the battery. When the alternator works properly; there should NEVER be a need to recharge the battery (unless you leave the lights on, or something similar). |
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I copy what you posted regarding the alternator/battery ground scenario. All I can add is that the present battery is brand new. Maybe I got lucky, as I have really asked a lot of this battery in the last week or so, trying to start, etc. It seems to work ok, really spins it over very well until at some point, it gets weaker as I keep trying to start the car. Anyway, the next day when I try to start the car again-it performs very admirably. If I get the car running, I'll make sure I get it checked, charged, etc to keep it in good condition. I will check out the alternator as you suggested. For now, my next step is to put in the plugs you suggested, with your recommended gap, and see what happens. If it's a no go, then I guess its new coil time. Thanks. |
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Replying to: shaggyman1 (May 28, 2009 11:08 am) The distributor ignition pickup is very sensitive to engine RPM, and is also prone to developing winding shorts in its sensor coil. If the sensor coil becomes shorted; it is very likely to create a situation where the engine will not have a spark below a particular RPM. In view of this; the observation you previously made about the engine only starting in first gear, but not in second; now sounds more like the ignition pickup is bad than either a module or a coil problem.
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I performed the test as suggested to check the alternator diode. Not even a hint of a spark when reattaching, and I did it a couple of times. Maybe my luck is changing with this baby. |
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Replying to: zaken1 (May 29, 2009 12:23 am) Last night I went through the checklist on AllData for "engine Cranks But Will Not Run" as far as the ignitor, but all the tests appear to be only for the circuit, without the ignitor connected. Circuits are good, and I'm going to RPL the ignitor with a salvage yard component, just to see if it helps. The sparks I do get are yellow, so I'm thinking either coil or igniter are not up to snuff, regardless of whatever other isuues there may be. I will try closing the plug gap to 30 first, and see if it kicks up, but I'm not confident that it will start in the one or two revolutions where I still have spark Having replaced the distributor, since the engine will not start, I can't properly set the timing- is 5 BTDC a good ballpark static time?
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Replying to: shaggyman1 (May 29, 2009 5:34 am) Regarding the crank sensor; I don't know how accurate the test procedures for that item are. I've heard of many instances where a defective crank sensor will cause the spark to shut down after the first few revolutions. Because of that; I would consider replacing the crank sensor; even though it tests good by the tests you have done. Hey; I also want to mention that Rock Auto just happens to have one remaining brand new Beck Arnley ignition module (which they call "Distributor Transistor Unit) for your car; which is a closeout purchase from some other warehouse. The regular price for that part is about $88; but they want $23.79 for this particular one. Beck Arnley is the highest quality supplier of import parts; and I have bought closeouts from Rock Auto before, and have never been disappointed by what I got. You can find this by going to www.rockauto.com looking up your car make, year, and model in their online catalog; selecting the engine size, and scrolling down to "ignition." There are separate listings for ignition modules and distributor transistor units; but they are really two different names for the same part. The Beck Arnley unit comes mounted on a metal heat sink.
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Put 3 new Autolite #63 plugs in, gapped at .030. Still just spins and will not start. I'm going to bed and worry about this tomorrow. Sigh.
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Replying to: zaken1 (May 29, 2009 8:28 pm) Replaced the Crankshaft Position Sensor- no change. Flashed the ECM to expunge any bad learned behavior- no change. Battery voltage with ignition 'ON' : 13.03V, 11.92V while cranking. (Drop of 1.11V) Coil + to Batt - : 12.89V at rest, 11.77V while cranking. (Drop of 1.12 V) Checking the Pickup coil in the distributor, I am getting 165 Ohms, rather than the 200 to 255 the book says, but I'm getting a pretty decent spark before it quits... Also, and probably more significant, the harness for the Crank Sensor should have a minimum of 1M Ohm on each side. I get the meg on one side, but the other comes out to only 24K Ohms. Thinking maybe ground was leaking through a fault in the ECM, I swapped for my other ECM- all same same. So My guess is that the Crankshaft Position Sensor is doing it's job, and the ECM is doing it's job, but the communication between them garbles the message and the ECM cuts off the spark after one camshaft rotation. (Why it would even have the idea of doing such a thing is a matter for another, more philosophical forum) Anyone know of a good reference for the wiring harness that gives connector colors and pin defs? (NO hair left- now gnashing teeth and looking for a good electrical engineer whom I can bribe with mead....)
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Replying to: shaggyman1 (May 30, 2009 4:07 pm) So I would definitely replace the pickup coil before doing anything else. Did you read the 24K resistance on one side of the crank sensor harness while the harness was plugged into the ECM? I don't believe that is how they intended it to be tested. Try disconnecting the harness plug from the ECM and then checking the resistance... I believe this will solve your problem; but since you asked about detailed wiring diagrams; there are two excellent ones out there. One is in the Chevrolet factory service manual for the 1996 Metro; and the other is in the Mitchell electrical systems manual for 1996 model year vehicles. The Mountain View, CA public library has both of those books. If your local public library does not have either one; they may be able to order one from the regional warehouse for your County library system. You can also buy those manuals online (but Mitchell manuals are very pricey). A friendly garage may let you Xerox those diagrams from their manual (if they have one). Or you can bribe someone to Xerox them from a library that has the manuals.
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