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#1578 of 1693 Re: Metro LSI [annielulu] by zaken1 May 28, 2009 (10:18 pm)
Replying to: annielulu (May 28, 2009 7:55 pm) If the new fangled plugs the parts person sold you were the Bosch models I had specified; they would have been OK at the time; but you'll now need ones that can be gapped for this (very important) test.   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.
#1579 of 1693 Zaken1 by annielulu May 28, 2009 (11:13 pm)
Thank you. I will get the plugs as requested.   Your knowledge regarding these matters is absolutely astounding.The plugs I recently bought and that are in the engine right now have green lettering saying "E 3.46" which I believe is the part number. There is no manufacturer name on them, just a green circle around the top and a logo that says "E3" in green with the "E3.46" as mentioned. Replies to this message: zaken1 (May 28, 2009 11:40 pm)
#1580 of 1693 Metro LSI- Plug info update by annielulu May 28, 2009 (11:18 pm)
OK, I just searched the internet-They are made by the "Bosch" company. That's what's in the car now.
#1581 of 1693 Metro LSI by annielulu May 28, 2009 (11:37 pm)
Zaken1:   One other thing-and I hope I am not driving you crazy, if I had the money right at present I would just take the car to a good shop to get it fixed..........but, alas funds are very tight right now. Here's the other thing. As you know the ground wire for the battery goes to 2 places: 1st-the smaller ground wire is connected to the fender well. 2nd. the bigger ground wire goes to the engine block and is bolted to it. What you have just related to me regarding "resistance" made me think of this: awhile back when I first started having starting problems the engine kept on running as I previously mentioned after I shut off the ignition switch, so, I quickly unlatched the hood and disconnected the battery at the "ground" cable connection to get the engine to stop. Well, the bigger ground cable that gets connected to the block overheated to the point where the insulation was burned through in one spot about 1/4 inch wide and around 2-3 inches wide. Now you can see the bare wiring showing through at this point on the ground cable. My thought is that that entire "ground" wire connecting to the block probably suffered from overheating and who knows how that affected it. I didn't worry about it at the time because I figured a ground wire would be ok as long as it was connected at both ends. But, the car started and ran for a couple of days ok even after this, so I did not let it concern me. But, even if it did cause a problem, could that affect the spark quality coming from the coil? I mention this because I'm trying to think of ANY reason to get this cute little car running again AND to stop asking you all of these questions. Replies to this message: zaken1 (May 29, 2009 12:04 am)
#1582 of 1693 Re: Zaken1 [annielulu] by zaken1 May 28, 2009 (11:40 pm)
Replying to: annielulu (May 28, 2009 11:13 pm) The brand of plugs you have is E3; E 3.46 is the heat range of an E3 plug. They may be manufactured by Bosch for the E3 company; but Bosch does not sell them themselves. Those plugs would be very difficult to fire; because they use an open chamber ground electrode. So please get the plugs I suggested. If your engine runs with a smaller plug gap; you can probably get by with it as is for a while. How long that while lasts remains to be seen.
#1583 of 1693 Zaken1 by annielulu May 28, 2009 (11:48 pm)
Roger-Wilco-Over & Out.   Thank you profusely.
#1584 of 1693 Re: Metro LSI [annielulu] by zaken1 May 29, 2009 (12:04 am)
Replying to: annielulu (May 28, 2009 11:37 pm) Battery cables do not melt their insulation for no reason. If the cable was not in contact with a hot object; it sounds like there was an electrical short somewhere in the vehicle; which drew a humongous amount of current through the cable. I don't expect the cable was damaged by the heat; but there is a good chance the short was in the alternator; and the alternator now has a shorted diode in it. Alternator diodes can be instantly destroyed if a battery cable is disconnected while the engine is running. They are not guaranteed to be destroyed; but there is a high likelihood that happened. And the effect of a trashed alternator could keep the battery chronically less than fully charged; as well as making the engine harder to start by draining off some of the power that normally would go to the coil. If the battery cable overheated at the time you began having starting problems; I expect there was a connection between those two events.   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).
#1585 of 1693 Metro LSI by annielulu May 29, 2009 (12:14 am)
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.
#1586 of 1693 Re: Distributor Broken [shaggyman1] by zaken1 May 29, 2009 (12:23 am)
Replying to: shaggyman1 (May 28, 2009 11:08 am) It is important to be careful about what words we use, when describing a car problem. Some later model cars have crankshaft position sensors and camshaft position sensors; but the 95 Metro 3 cyl has neither of those. When I first read your post, I didn't think twice about it; but on reflection, I now realize that what you probably meant by the "crankshaft rotation sensor" is the distributor ignition pickup.   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. Replies to this message: shaggyman1 (May 29, 2009 5:34 am) zaken1 (May 29, 2009 8:28 pm) shaggyman1 (May 30, 2009 4:07 pm) and 3 more...
#1587 of 1693 Metro LSI Alternator Diode Test by annielulu May 29, 2009 (12:24 am)
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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