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Hatchbacks Chevrolet Metro/Geo Metro Chevrolet/Geo Metro
1692 messages, Last post on Oct 24, 2009 at 5:27 PM
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Replying to: alniter (Jul 10, 2009 10:27 am) |
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I know I have seen this on one of the forums, but can't seem to find in in search. 1996 Metro G10 runs perfectly, EXCEPT..... Idle surges under electrical load such as blower fan or headlights. Idle jumps up to 2000 RPM and drops to 1500 Rpm about once a second for 8 or 10 cycles, then returns to normal idle until the throttle is opened even slightly- then repeats. It does this when driving whenever the pedal is slacked off during deceleration, resulting in a rather unnerving pulsation, as if one was tapping on the accelerator pedal. Troubleshooting charts don't seem to address this adequately, so if someone can steer me in the right direction I would be very grateful. TIA
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Replying to: shaggyman1 (Jul 18, 2009 11:50 am) But it may take several tries to get it zeroed in to where it runs best. Before attempting to adjust the TPS; the igntion timing should be set to 6 degrees BTDC with a timing light; while the check connector terminals are shorted as described in the manufacturer's instructions. And the spark plug gap should be set to .042" I hope this helps!!
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Replying to: zaken1 (Jul 18, 2009 12:22 pm) I thought I might have found the root of all evil: I set the timing, and was tinkering with the TPS when I glnced down and saw the timing move a couple degrees. As the diagnostic connector was jumpered, I got very suspicious- on probing the ground terminal, I found NO ground. Backprobed the wire and got good ground. Fine! I cut the wires and twisted them together: lo and behold! the timing was sitting at 1 BTC, not the six I had set it at. It appears that I have been running retarded forever! Gaaahhh! Hope I didn't burn another valve.... I tried setting the TPS with a feeler, etc, but it would not start or run cold- kept tinkering until I found a spot midrange (richer) that would allow it to start and idle, but it still dies when given any throttle, unless I let it warm up for two or three minutes. I drove 45 miles, and the ECU set a code of P0123: TPS Switch A Circuit High Input. Checked the input from the ECU, and it is a steady 5V, like it should be. Cleared the code put in a new battery, and am anxiously awaiting tomorrow's trip to see if the new battery helps any. (okay, but sometimes a straw is just what you need to grasp...)
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Replying to: shaggyman1 (Jul 23, 2009 1:33 pm)
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Replying to: zaken1 (Jul 23, 2009 2:12 pm) I'm going to find a shady spot and do some backprobing in the harness. The coolant sensor has been replaced, and doesn't seem to be the culprit, even though it certainly appears that temperature is the determining factor.
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Replying to: shaggyman1 (Jul 23, 2009 2:27 pm) They also used a different MAP sensor in the 1989-91 3 cyl models; which I find runs a bit richer (which I think would be a benefit in your situation). It has a thick plastic section where the mounting bolt goes through; while the later unit uses a metal plate in that location. It will mate with your harness plug. If someone installed the wrong MAP sensor, or if your engine's compression has now changed enough to have leaned out the mixture; the earlier MAP sensor would be worth trying. Mine is labeled 18590--60B00, and underneath that is another line reading 079800--1540.
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Replying to: zaken1 (Jul 23, 2009 4:48 pm) VIN code 6 refers to the fuel system (8th digit in your VIN), 6 being Throttle Body Fuel Injection- so a G10 with TFI. All of my TPS units appear to have only one switch (idle), rather than two, (the other being for WOT) but from what I've gleaned so far there is a third type with a continuous variable resistor as used on the 1.3 with port injection. I'll check on the MAP- I think mine is plastic, but I'm not sure. |
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Zaken1: I'm still fooling around with the car. I have checked EVERYTHING I could possibly think of and have hopefully narrowed it down to the COIL. I have been to auto parts stores here in Las Vegas. No one really seems to know what the correct coil should be. I bought one, but it was not the right one. Could you please tell me the correct coil manufacturer and part number. I checked the Rock Auto parts site, but I am still confused. Thanks very much.
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Replying to: annielulu (Jul 26, 2009 12:16 am) The coil specification is not nearly as critical or restricted as your message implies. Virtually ANY 12 volt coil that has a 1.0-1.2 ohm primary, and is intended for electronic ignition applications will work on your car. I have used literally dozens of different types of coils on Metros; which work just fine. In the Rock auto site; both the Airtex # 5C1069 or the AC Delco # E536 would be suitable. Basically, any coil listed for US model 1993 Metro LSI convertibles will work. And these coils will all look like a tin can, with the high voltage terminal and the two primary terminals together on the same end. The only listings which are not suitable are the ones for the Canadian models or the non convertible US models. And that difference will be very obvious; because the unsuitable coils will be more oval than cylindrical, will have an external metal core surrounding the coil, and will have the high voltage terminal on the opposite end of the coil from the primary terminals; with the primary terminals located inside a plug that will not match with your harness wires. Now, there are other types of tin can style coils which are not suitable for the Metro; but they would not be listed as replacements for that vehicle. I believe that you already replaced the coil with a new one some time ago. If you think the parts clerk sold you a coil that was not intended for the Metro, and you can post all the numbers and markings, and brand information printed on the coil; I'll probably be able to confirm whether or not it is suitable. I understand that you have checked everything you could possibly think of; but you must bear in mind that you are dealing with electronic parts here, which cannot be checked without meters and test equipment. Because you do not have this equipment, there are many items in the electrical system that you are not able to check. And it is certainly among those items where the problem lies. Electricity may not be visible; but problems with this invisible force still can prevent the car from running, even when the parts physically look just great. Did the EVERYTHING that you have checked include the distributor pick up coil, and the ignition module, and what about the test I suggested for bypassing the ignition switch??? Pardon my skepticism; but since you are not skilled in this area, I would at least need to know the details of what you did, explained as completely as possible, in order to confirm in my own mind that each of these items is not the source of the problem. My experience has been that people all too frequently test an electronic component by performing some sort of rudimentary electical test that is either inappropriate, inconclusive, or is improperly applied; and then become totally confident that they have eliminated that part as the source of the problem. And that is why I am requesting full and complete disclosure. |
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