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Hatchbacks Chevrolet Metro/Geo Metro Chevrolet/Geo Metro
1694 messages, Last post on Dec 06, 2009 at 4:44 AM
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Replying to: annielulu (May 28, 2009 1:32 am) It could be possible to bypass the ignition switch; but it would require figuring out which terminals or wires to use; and probably taking the covers off the steering column. A wiring diagram would also be highly desirable in such a situation. A wiring diagram could be found at a good public library. There is one at a library in my area. But all this stuff is extremely time consuming; and potentially frustrating. So the question really comes down to whether saving the last possible cent is more important than saving your time and patience. A new ignition switch from Rock Auto online is about $200; but there are few enough wires in the harness that bypassing the switch is not too formidable a task. However; you would at least need a 12 volt test light; if not a meter. A new coil is $27 from Rock Auto online. I expect it is far more likely that the ignition switch is bad, rather than the coil; but I couldn't guarantee that. So please tell me how you want to deal with this: 1> Take it to a shop. 2> Buy a new coil because it is the cheapest option and hope it fixes it. 3> Buy a new ignition switch. 4> Buy a test light or a meter, and try bypassing the ignition switch; which may also require getting some soldering or crimping equipment and a wiring diagram. |
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Replying to: shaggyman1 (May 28, 2009 7:17 am)
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Replying to: zaken1 (May 28, 2009 10:21 am) I replaced the distributor (and cap & rotor for the third time!), and put in a new set of plugs. I get spark at all cylinders through either one or two rotations- then nothing. Same for coil- fires either 3 or 6 times, then squat. I suspect this might have been taking place for a while, as it would start when first pushed, but not while cranking. If it didn't start on the first clutch pop, it would refuse until ignition was cycled on and off. And it would not start in second- only first or reverse. Could the crankshaft rotation sensor have a dead spot, and only report rotation over 500 RPM or something? Maybe this is a Metro with a Gremlin......
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Zaken1 I'm going to try a new coil and see what happens. Thanks very much.
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Replying to: annielulu (May 28, 2009 12:50 pm) |
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Zaken1 Auto Zone here in Vegas has the coil in stock for $33.00 which I think is an ok price. I called Checker Auto and those guys wanted $97.00 and could not get it until 6/2. So I'm going to pick it up tomorrow at Auto Zone. Could you elucidate as to why the ignition switch might be the problem, based upon what I described to you about it. What are the workings of the switch and how would it impact starting. Thank you so much for all of your previous assistance.
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Replying to: annielulu (May 28, 2009 6:15 pm) I agree that the $33 is an OK price. But I'd like you to first make one simple test, which costs nothing; although you'll need a spark plug gap gauge and adjusting tool to do this. This test can only be done if your car does not have Bosch Platinum +2 or platinum +4 or Fusion plugs in it. I believe you said it now has Autolites; which will be fine for this test. Please take the plugs out; clean them if they are wet with fuel; and adjust the electrode gap to .030" (0.75mm). Then put them back in and try to start the car. If the car runs, you can leave the plugs gapped at .030". When you tell me what the result of the test was; I'll explain more about the coil and ignition switch. |
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Replying to: shaggyman1 (May 28, 2009 11:08 am) The symptom you describe; of getting sparks only on the first one or two crankshaft rotations; sounds like either a bad coil or a bad module. |
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Zaken1 The guy at the parts store sold me 3 new plugs that did not have to be gapped. I took the old ones out that were less than a year old (ones that had to be gapped) and replaced them with these new fangled ones, just to make sure it wasn't the plugs. I kind of wish I bought ones that had to be gapped, but it's too late now, unless you think I should change back. As far as the coil-I specifically told parts guy that it was a 1.0, 3 cylinder-convertible, and that was the price they gave me. If I have to get it, I will bring the old one with me when I pick up the new one, for comparison. You mentioned that you had an issue with the coil spark description that I related to you when tested. Can you explain your feelings on that and talk about the coil and ignition switch. This car is really starting to bug me. I really want to like it. I know you have had great luck with yours. As an aside, I read most of all of your old various posts, and thought maybe that it wouldn't start because I didn't have the seat belt engaged whenever I tried to start it. I ran down to the garage full of hope and expectation-buckled up the seat belt and turned the key............and you can surmise the outcome. Darn. Thanks again for your tireless efforts, I NEED to get this car going. Previous to this I drove a 2002 Jag XKR convertible which never gave me any trouble. I paid a LOT of $$ for it. But, that was 2 years ago before the Vegas realty market crashed. Going from an XKR to a Metro is not too much fun but, right now I need to get mobile to run my job. Bumming rides is a real pain.
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Replying to: annielulu (May 28, 2009 7:55 pm) If the plugs the parts person sold you were not the brand and part number I specified: I need to clarify that whatever I say about spark plugs is HIGHLY SPECIFIC; and in no case is it appropriate to substitute some salesperson's generic preference. All brands of plugs are NOT the same. Some brands of plugs just will not run properly in the Metro engine. Metro engines are notoriously touchy in that respect. These salespeople inevitably don't know the fine points of plug selection; nor do they know which brands of plugs work well in Metro engines; nor do they know the difference between plug requirements for Metros of different years and model. So PLEASE, PLEASE only use exactly what I specify (even if it means going to a different store or special ordering a specific plug type.) I can't stress this enough!!! I would like to know the brand and part number of the plug that doesn't need gapping; which is now in your engine. That information is printed on the plug porcelain or metal shell. The brand may be in one place, and the part number somewhere else. The plugs I would now like you to get are any of the following four part numbers: AC Delco # R43XLS; or Bosch Super Plus # 7907 (This is a new part number, and may not be available; but DO NOT USE ANY OTHER BOSCH NUMBER); or Champion # 405 (also referred to as RN14YC); or Autolite # 63. Please do not substitute ANYTHING ELSE. You will need to reset the gap for whichever of these plugs you get to .030" (which equals 0.75mm). When a spark is mostly yellow; it means the arc has a lower temperature than normal. A normal spark is blue/white. A spark that is yellow could be caused by shorted windings in the coil; or it could come from excessive resistance in the ignition switch; or from resistance in the wiring connections anywhere between the battery, the coil, and the ignition module. Ignition coils are made by winding many thousands of turns of fine wire in a series of layers around a metal core. Each length of wire in the coil is insulated from touching any adjacent wires with a thin layer of lacquer. Sometimes heat, or vibration, or excessive electrical stress, or aging can lead to breakdown of the insulating layer on a particular section of wire in the coil. When this happens; the copper conductor in two adjacent wires can touch. This creates what is known as a "short circuit;" in which the electricity can detour through the shorted area; rather than flowing through all the windings in the originally intended sequence. Coils function by resonating (the electrical flow within the windings vibrating in harmony with the winding shape and size). If a short develops in a coil winding; it can interfere with the resonance; just like someone walking across a racetrack can interfere with the rhythm of movement of the runners on that track. When the resonance of a coil is hampered; the typical result is a reduction of the energy in the spark; which in turn reduces the spark's temperature. And the lower the temperature of a spark; the less effective that spark is in igniting a compressed air/fuel mixture. An ignition coil gets the energy which is used to make sparks from power that comes from the battery. That energy flows through the battery cables, the ignition switch, the wiring harness, the coil, the ignition module; and then back to the battery. The ignition switch is the most vulnerable element in that system; because it contains movable metal contacts, perhaps 1/8" in diameter; through which the coil power flows. These contacts are moved so they touch each other when the key is turned on; which allows battery power to flow to the coil. But the contacts age over time, and thus become oxidized and pitted. When the surface of a contact erodes; the amount of area which actually touches the other contact becomes smaller and smaller. The smaller the area becomes; the hotter it gets when power flows through it. (Incidentally; when the battery is not fully charged; the voltage (electrical pressure) it produces becomes less; but the coil is designed to draw a constant amount of power, regardless of the voltage of the source. So when the battery voltage drops; the coil compensates by drawing more current, to maintain the same power level). The more current flows through the ignition switch; the hotter the contacts get. In extreme cases; the hot contacts can actually stick to each other. (and that's why the engine doesn't stop when you turn off the key when the battery is low). And this heat creates an escalating rate of degradation of the switch contacts and a progressively greater loss of efficiency in transferring power to the coil. The less power that reaches the coil; the lower the spark temperature becomes. And this makes it harder and harder for the spark to ignite the fuel mixture in the cylinders. This situation will continue to get worse; until the switch conducts so little power that the spark from the coil can no longer ignite the fuel in the cylinders. And that's when the engine will no longer start. |
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