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Geo Metro Engine Questions

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Comments

  • zaken1zaken1 Posts: 556
    edited May 2010
    Here are several possibilities, listed in descending order of likelihood:

    1> Try replacing the intake air charge temperature sensor (located in the air cleaner housing). And be sure that there is no aftermarket "performance chip" that has been connected to the IAT sensor wiring.

    2> Try replacing your coolant temperature sensor. The sensor on your car has two sections; one section drives the temperature gauge, and the other section tells the computer when the motor is warmed up. If the section that talks to the computer was defective, it would make the computer think the engine was always cold; which would create an excessively rich fuel mixture when the motor was warm. That could substantially raise the idle speed.

    3> Locate the idle air control valve (mounted on the driver's side of the air cleaner close to the firewall and the throttle body). There is a vacuum hose between the IAC valve and the intake manifold, below the throttle body. Make sure that all the vacuum hoses are securely connected and there are no cracks, tears, holes or any type of leaks. Check the vacuum hose from the brake booster to the intake manifold, and the hose from the back of the throttle body to the MAP sensor for similar leaks.

    4> There is a relay on that car called the throttle control relay (also sometimes called the idle speed control relay). Try replacing that item.

    5> There is a part called the throttle position sensor, which is mounted on the passenger side of the throttle body. This sensor is mounted with two bolts, which pass through elongated slots; so the sensor position can be adjusted after the mounting bolts are slightly loosened. Carefully note the position of the sensor mounting bolts in their slots, and then loosen the bolts just enough to allow the sensor to be turned by hand pressure. Turn the sensor counterclockwise a small amount, and retighten the mounting bolts. Try driving the car after making that change, and see whether the idle speed is reduced. This is a very sensitive adjustment: It may be necessary to repeat this procedure several times; before you reach the optimal adjustment point. If you turn the sensor too far counterclockwise; the motor will begin to hesitate or falter when throttle is applied.

    6> Make sure the throttle cable is adjusted to have enough play to allow the throttle to close completely when the motor is warm. You should be able to grasp the pulley for the throttle cable on the driver's side, and be able to turn it clockwise until you can feel the linkage hit the stop screw. If the cable is adjusted too tight; you'll feel the cable become tight and prevent the pulley from turning before the linkage hits the stop screw. Sometimes someone breaks the factory seal, loosens the lock nut on the stop screw, and incorrectly adjusts the stop screw so that it does not let the throttle close fully. In that situation; the throttle stop screw must be readjusted to allow the throttle to close further. THIS IS AN EXTREMELY SENSITIVE ADJUSTMENT.
  • raywisraywis Posts: 1
    Friend's towed metro will start one morning & then will not for a couple of days? cranks but not run. fuel pump,& filter have been replaced. Also distributor cap & rotor all by a certified Mech. didn't correct the problem. Any ideas?
    RenoRV
    mrtaxpayerch@yahoo.com
  • zendenzenden Posts: 62
    This could be many things wrong. Basically you should diagnose first with the symptoms; as in do you see a pattern? Could it be a lot of moisture in the air where you live? GEO 3 cyl’s can have troubles with that; unique to a 3 cyl especially if one of the cyls are week to start with; If you suspect a moisture problem it is usually an air gap where the spark plug boot plugs in to the sparkplug. The rubber boot must seal the sparkplug hole going into the head or condensation builds up around the sparkplugs.
    If moisture is not the trouble then when it will not start check for spark and fuel, it takes both of them to fire up. The coil should throw a half inch spark while cranking. The fuel pump should run for about 5 seconds as soon as you turn the key on. Some times people replace fule pumps when the relay was bad, or a bad connection some ware. There are ignition relays and fuel pump relays in cars. Ignition switches go bad at times; coils go bad and many more. So find out if it is a lack of fuel or ignition spark, because if you have enough of each of them, then it opens up a box or many more questions related to timing, compression, ect.
  • 3door3door Posts: 2
    zaken1 Thank you for the information, I'll let you know how I make out.
  • heavyhookheavyhook Posts: 12
    I was cruising down a local Hwy at 60 mph in my metro with 81K miles when she just quit. I popped the hood to try and find out what hat happened. The main 60 amp fuse had been blown. I checked the battery hot wire to the fuse panel, starter and alternator for a short or chafing. Nothing found. I took the top off the blown fuse and inserted a dime to jump across the fuse. No sparks, no wires , nothing seamed to be getting hot or warm. Tried to restart, cranks good but wont start, took the distributor cap off and had friend crank motor over. Rotor spins fine. so timing belt is not broken. I had replaced it at 55K. Re installed cap and pulled spark plug wire off # 1 cyl. cranked motor over again but no spark. Checked for power and have hot wire up to coil. I havent checked resistance on coil. Not really sure of procedure for checking coil. Rotor and cap contacts are clean. No points looks like electronic ign. Any Ideas would help, Thanks
  • zaken1zaken1 Posts: 556
    edited June 2010
    This is an unusual situation! The most likely cause of the fuse blowing would be that a diode in the alternator shorted out. The diode or its circuit wiring could have then gone open before the fuse blew. That would now leave no sign of a short.

    How did you test for spark at the plug wire? The wire terminal is recessed far enough in the plug boot that it probably wouldn't be possible to see a spark unless you had inserted a bolt or spark plug into the wire, and then held the plug so that the threads were pressed against a grounded object, or held the bolt head about 1/4" from ground. If the sun was shining, it would make it even more difficult to see a spark. A more reliable way to test for spark would be to disconnect the distributor end of the coil wire from the distributor cap, and hold the wire so that the metal end (which projects out beyond the boot) is 1/4" from ground while the motor is being cranked.

    If you really don't have a spark; try disconnecting the heavy power wire from the alternator; and then check for a spark from the coil wire again. It might be that there is a partial short remaining in the alternator, which is shunting power away from the ignition system.

    I would not bother trying to check the coil resistance; it is highly unlikely that it would short out completely enough to blow a fuse. Besides; the fact that you have battery voltage at the high side of the coil proves the coil is not shorted out. If it was shorted, there would now be little or no voltage at the coil high side (as that point would now effectively be grounded).

    It sounds more likely to me that whatever blew the fuse is also now keeping the motor from running. This could be a short in either the fuel pump, fuel injection, ECM, or ignition circuit. There are relays which control most of those circuits. If a relay went bad, it would shut the motor down; and might also have blown the fuse. The fuse block that contained the 60 amp fuse also contains the fuel pump relay and several other relays. Many of them are physically interchangeable.

    So I would try turning the key on and listening for the sound of the electric fuel pump. The fuel pump normally will run for about 5-10 seconds after the key is first turned to the position where the dashboard warning lights come on. If it is noisy where the car is located, you might need to have someone stand next to the rear wheel on the driver's side so they can hear the pump better. Holding your head out the open driver's window may also make it possible to hear the fuel pump; but don't do this with the driver's door open; as that will cause the door warning buzzer to sound.

    If you do not hear the fuel pump when the key is first turned on; then try exchanging the relays that are mounted outside the fuse block, on the front side. You can also do this with any relays inside the fuse block that are the same size. It would also be important to check all the fuses in the fuse panel under the dashboard, on the driver's side.

    If you post your experiences with trying to get a spark and the fuel pump to run, I'll keep an eye on this site; inn order to give you additional suggestions based on your feedback.
  • heavyhookheavyhook Posts: 12
    With reguards to checking for spark. While broken down on the side of the Hwy, I used a new alligator clip that is about 2 inch long and on one end is a 3/16" round end you can use to crimp on the end of a wire. I inserted that end into the end of the #1 plug wire. I held it 1/8" off the metal housing of the distributor while having a passenger crank the motor over. NO SPARK ! I have worked on and continue working on muscle cars for the past 35 years. I am far from a novice. When the engine quit running I checked the fuses under the hood first. I had zero electrical power inside the vehicle to 100% of the systems. I grabbed my 12 volt test light from the tool bag I move to every car I drive. The Metro had been drove once it the last 16 months. I am relocating about 100 miles my from current home. I changed the oil and filter, checked all the fluids and checked the air in all the tires. Shoot, I even gave it a bath! I borrowed the Optima battery out of my 71 Mach 1. I made the 100 mile trip with a/c blowing cold air all the way. About a 2-1/2 hour drive without a problem one.. I parked the metro in my new garage, removed the battery to return to my Mustang. While on a return trip moving things to my new home, My 2004 F-250 Diesel had a cam sensor go bad. Since my new home is out in the country in North Central Texas, I had to order the part from a O'reilly's auto parts store which is about 15 miles from my new home.. The next day I borrowed a Optima Battery from my F-250 truck to run to the retrieve the cam sensor. My little car fired right up as usual. I made it about 3 miles from my house when the Metro died all at once, not a hint of a impending problem.
    My father bought this car new in 93. I purchased it from him in 03 with 61K on the speedometer. The only mechanical problem I have ever had is replacing the clutch about 2 years ago and the alternator about 6 months later. I have only put about 1,000 miles on the Metro since then. I did have a problem with the first replacement alternator I purchased. With just the slightest amount of tension on the alternator drive belt the bearing in the front side of the case would cause it to lock up. I had the before mentioned parts store order another alternator. The one thats on the car now is that replacement. While installing the alternator I encountered a similar problem only not as bad, I could tension the belt by just pulling on the alternator case by hand and tighten it down there. Any more tension would lock the front bearing down as before but it was enough to keep the belt from slipping. All seemed to be going good until the latest installed alternator had about 500 miles on it. Then the front bearing started squealing for just a couple of seconds after the engine was started then would quit and seamed fine..
    I can see that if a diode shorted out where it could blow the 60 AMP fuse. If it were the fuel pump or ECM ect. I would think It should have blown a smaller fuse that protects that specific circuit. As I mentioned in my first post. To blow the 60 Amp main fuse, seems it needs to be a very serious, high amp draw short in the alternator or starter motor. I checked the main hot leads from both back to the fuse panel and battery for chaffing but found none. As I mentioned before while broke down on the side of the road I used what I had, a dime in the top of the fuse where the bimetal bridge burnt out. There was no sign of a short still existing when I jumped across the blown fuse. All systems seemed to have full power. I had my flashers on for a good 45 minutes after jumping across the blown fuse. The emergency flasher lights were bright and working correctly. All the way back to my new home as I was being towed. My test light was burning bright when I checked the hot wire to the coil.
    It will be another week before I can get back down to where the Metro is to do anything else. I am not sure how your suggestion of unplugging the coil wire from the distributor is supposed to work . If you try to short directly from the coil to distributor feed there is no way for the current to build up inside the coil to jump a gap. Anyone cranking the motor over would have no effect on generating voltage to test for a spark if the current is not being run thru a distributor giving the coil time to recover between each plug firing cycle.
    Well thats about all the history I can provide. Ya know, 35 years ago when everything had points and mechanical fuel pumps It was an ART to fix a ignition or fuel system problem and there was a 90% chance that with a few tools and a few years experence you could get the old car fired back up and get home on your own. Now its 90% science, You take what ever gizmo you suspect to a parts store where some young man, who has only being supporting his self for 3 or 4 years will do there best to sell you every sub-component in the system you suspect of being at fault. And this is what we call progress!!! Thanks for your input Doug Walker / Whitney,TX
  • zaken1zaken1 Posts: 556
    Doug,

    Thanks for the feedback. I'll try to clarify some of the points you brought up here. It sounds like we may be miscommunicating about the coil wires used to test for spark. Of course the primary (12 volt) feed must be connected between the coil and the electronics in the distributor (which take the place of the good old points and condenser) in order for dwell current to charge and discharge the coil. But I wasn't asking you to make any changes in the primary circuit. What I suggested was for you to disconnect the distributor cap end of the 7mm diameter high voltage wire that goes from the coil tower to the socket in the center of the distributor cap, and hold the distributor end of THAT wire close to ground. This wire is totally independent of the little primary wires that feed 12 volts to the coil to charge it. So the coil will still produce sparks during this test; just like it does when you disconnect one of the 7mm plug wires from a plug and hold it close to ground. The high voltage current from the coil does not need to pass through the distributor cap or rotor in order for the coil to be recharged. It is only the primary circuit's little, 12 volt colored wires and the low voltage electronics in the distributor (that substitute for the points and condenser), which are needed to charge the coil. If the primary circuit works; the coil will produce sparks; regardless of whether they go through the distributor cap or not. (If that was not true; the new cars that have an individual coil on each spark plug and no distributor would not be able to work; as their plug wire goes directly from the coil to the spark plug). It is important to understand that once the coil is charged by the primary current; it will jump a spark anywhere it is strong enough to go; regardless of whether it is a large or small gap. The spark has already been generated inside the coil; it does not depend on the size or routing of the gap in order for it to fire or to recharge. Please trust me on this; I have made a living as an auto electrical specialist for over 40 years, I also taught courses in engine theory at MMI in Orlando, FL, and I have been developing and refining my own electronic ignition circuit since about 1970. I also have owned a 1990 Geo Metro 1.0 since 1992. And I have answered over 1,900 questions on the Edmunds Answers forum in the last 18 months (where I am now ranked # 3 in the last 30 days). Sorry if that sounds like boasting; but my students repeatedly told me that electronics was the most difficult part of the course for them to understand; and I often had to correct misconceptions they had about electronics before they could gain a clear sense of what was going on.

    The reason I wanted you to check for spark at the coil wire instead of the plug wire is that the distributor cap and rotor can sometimes ground out from a high voltage arc breaking down their insulation. If you bypass the cap and rotor; there is that much less chance of a defective external part messing up the test. Also; the timing belt can sometimes slip and still turn slowly; or even stop turning after you put the distributor cap back on. There are several other spark tests which can be made with the cap off; which may prove valuable in sorting out what is going on here.

    You are correct in concluding that it must have been a high current arc which blew the fuse; and that most components would have lost smaller individual fuses if they had failed. Incidentally; the starter is not fused; since it normally draws as much as 100-150 amps, so it could not have been the item which blew the fuse. This pretty much leaves the alternator as the prime suspect. FYI, over the years, I have gotten so many defective rebuilds from O'Reilly that I absolutely refuse to buy any more rebuilt components from them. They apparently have the work done in Mexico by people who are told to not replace anything they don't have to. It is criminal to not replace bearings in alternators; no matter how good they may look. So, in order to remove one more unknown factor from this process, I request that you please disconnect both the power cable and the smaller plug from the alternator, and wrap or tape them up while doing the rest of the testing. If there is a NAPA store in your area; that is a much more reliable place to get rebuilt parts.

    Regarding the distinction between auto repairs being an art or scence; 35 years ago, I would have become a rich man if I had a dollar for every carburetor that someone wrongfully condemned because they weren't able to figure out the difference between a fuel system and an ignition problem. About 90% of the car problems people would bring in to my shop were ones they believed to be fuel system problems; but when I tested and repaired the car; 90% of the problems which the people had reported actually turned out to be ignition problems. And about 90% of the carburetors I adjusted were previously set too rich; because excess richness is a great band aid for covering up improper ignition adjustments. So science was just as important to know in those days as it is today. But I will agree that the old low compression, mildly cammed motors are far more forgiving about tuning errors than todays precisely calibrated, low emission, fuel efficient motors.
  • trmechantrmechan Posts: 5
    Tried moving plugwires. Could not turn dist. far enough to get stated.
    Had to move timing belt off one notch on cam gear to get unit started and timing
    set. Engine still runs rough.
    Need to find out how to set tp sensor on 95 GEO with upgraded emissions.
    Sensor only has 3 wires in the plug. MOtor manual says to use a Tech 1
    scantool and I don't have one.
    I may also have another problem upon inspection of the intake I found the locknut
    on the throttle is loose. I don't know if it has been messed with.
    Please help.
  • zendenzenden Posts: 62
    You need no TECH 1 to set the TPS
    With Key On Use .14 inch or 3.5 mm feeler gage between throttle stop screw and throttle lever;
    If the idle speed control motor plunger is making contact with throttle lever screw, then you must bring Eng. up to normal operating temp so that it will not touch it. Then back probe the TPS with the feeler gage in place. The TPS has 3 wires, using a DC volt meter on low scale puncture the middle wire with your probe; hold it there and probe the outer 2 one at a time until you get your reading. TPS should read between .98 and 1.02 DC volts, if not adjust or replace it. A good TPS will smoothly increase in volts as you increase the throttle. let me know how it goes
  • zaken1zaken1 Posts: 556
    I don't want to interfere with Zenden's good and helpful advice; but I think you need to consider the following: The compression pressure in this motor must not be less than the minimum manufacturer's specification (it must be greater than 165 psi, and optimally at 195 psi). The compression may be low either because it has a non-stock camshaft, or the camshaft timing has been altered by the use of an offset keyway, or because the head is cracked, warped or the valves are not seating properly. If that is the case, then there is no way that it can be made to run smoothly or properly. In that situation; trying to readjust the TPS or the idle air bypass, or the throttle stop will just throw you into a bottomless pit where it keeps running worse and worse despite everything you do. So please run a compression test BEFORE changing any of the engine adjustments. That will save you all kinds of grief.
  • zendenzenden Posts: 62
    edited June 2010
    It sounds like you may need this info. There are two types of upper timming sprockets; the solid type and the 5 spoked type. This is how to alingning the common 5 spoked type.

    The (Crankshaft) woodruff key will be at 12:00 ; this will make the lower marks line up.
    The (Camshaft) has a alingment pin sticking out, it will be at 6:00 o'clock then put the cam sprocket on; ( it has two slots coming out from the center hole ) when alingment is correct the slots will be pointing toward 1:00 o'clock and 6:00 0'clock ( NOT at 6:00 and 11:00) . Now all timing mark will line up; both will point upwards. This info is correct for any GEO's with a 5 spoked type cam sprocket..
  • trmechantrmechan Posts: 5
    I can use any information I can get. I got the car from a friend, with a blown headgasket. He had tried to get the car running but couldn't find the problem.
    I checked it for him and told him the headgasket was bad. He didn't want to mess with it any more. So I bought the car from him and changed the head gasket, had the valves ground, and head surfaced. Put it together and couldn't get it to start without removing the bolts from the distributor and turning the dist. beyond its limits. The only way to get is started within dist. limits was to move the timing belt off by one notch. The compression is about 180psi on all cyl.
    The biggest problem I am running into now is trying to get things back to where they are suppost to be. From talking to previous owner I now know that he played with the idle screw, tp sensor, ign timming, cam timming, and idle control.
    So I have my work cut out for me.
  • trmechantrmechan Posts: 5
    edited June 2010
    I Researched cam timming, and did have the timming set correct until know. I don't know why I have to move the cam back one notch, unless their is a computer problem. Thanks for conferming the correct setting anything is in question right now.
  • zaken1zaken1 Posts: 556
    There are two different types of distributors which were used on the 1.0 motor. The 1989-1991 motors used a distributor with a dual diaphragm vacuum advance unit that had 2 vacuum hoses; the auxiliary advance diaphragm (outer hose on the distributor) was connected to a spigot on the cyl # 1 intake manifold runner, and the main advance diaphragm (inner hose on the distributor) was connected to the center spigot of the three spigots on the lower front edge of the throttle body. Later model throttle bodies (on engines that did not have vacuum advance distributors) only had 2 vacuum spigots; the one closer to the passenger side is used for the EGR system; while the one closer to the driver's side is used for the vapor purge cannister.

    The 1992 and later models used a distributor which does not have vacuum advance, and instead has an electronic advance circuit. With this distributor; the vacuum spigot on the # 1 cylinder intake runner should be capped off, and if there are three vacuum spigots on the throttle body; the center one should be capped.

    In this situation, I would first make sure the timing notch on your crankshaft pulley is really at TDC. That can be done by lining up the pulley notch with TDC on the degree scale on the timing cover. Then pull the spark plug in # 1 cylinder, insert a 1/4" rod into the plug opening, and rock the crank pulley in both directions while holding the rod; to see if the piston comes up any further than where it was when the timing marks were lined up. If the timing marks are true; you can trust them for use in further tests. But if the marks are not correct; the pulley may be the wrong model; or the Woodruff key may be missing or broken. If the key is not in place; the mark may be able to move around, which would make it impossible to set the timing accurately enough to tune the rest of the settings. So you'd need to fix that issue before going further.

    I'm going to give you a little more information here, but please do not apply it until you've gotten the timing marks to be trustworthy.

    Have you tried connecting a timing light to # 1 cylinder, and seeing where the timing is when the engine is idling as slow as possible (with any vacuum hoses disconnected from the distributor and plugged). If your motor has the electronic advance distributor, the check connector terminals next to the firewall on the driver's side should be shorted together with a jumper wire or a paper clip to disable the electronic advance circuit, before checking the timing. The stock ignition timing on the 1.0 motor is 6 degrees BTDC @750 RPM or less.

    The normal plug wire positions are; the # 1 cylinder (closest to the fan belt) plug wire is at 12 o'clock on the distributor cap. The # 3 cylinder (closest to the distributor) plug wire is at 8 o'clock on the cap. And the # 2 cylinder (center cylinder) plug wire is at 4 o'clock on the cap. The distributor rotor rotates counter-clockwise.

    If you've checked and applied all the above information; and the motor still does not run with the distributor set in the normal range; see where the ignition timing now runs best when checked with a strobe timing light. If it is advanced a lot (notch on the pulley is further to the left than the stock setting on the degree scale) from the stock setting; then move the timing belt back to the stock setting, and try moving all the plug wires one position clockwise in the cap, and then turn the distributor back to the stock range. See if it now runs well like that.

    But with the timing belt still set one tooth off; if the motor now runs best when the ignition timing is very retarded from the stock setting (mark on the pulley is located to the right on the degree scale from the stock mark); set the timing belt back to the stock position, and move the plug wires one position counterclockwise on the distributor cap, and then turn the distributor back to the stock range. See if it now runs well like that.

    Let me know how it all turns out.
  • trmechantrmechan Posts: 5
    edited June 2010
    For Zenden and Zaken1 I think I found the problem. Will checking cam timming once again, and checking timming marks on crankshaft I found that the key for the crank gear was broken. Both the gear and the crank are badly worn from the key working around. Know I will have to decide what to do with the vehical.
    Fix or Junk.
    Thanks to both of you for your very good and experienced help.
  • thebeechboysthebeechboys Posts: 2
    edited July 2010
    I am looking to purchase a 4 door Geo Metro LSI with automatic trans not sure of the year, early 91 with 43,000 miles. When driving the car and accelerating after a red light or stop sign, there is a rattling noise that sound like it is comimg from the right side of the engine near the upper right cowl. I was told it might be a loose bolt in the cowl. I do not agree with this? The rattling noise is of fairly short duration and occurs almost 100% of the time. Otherwise the car runs very well.
    The noise occurs with the a/c on and off. There were a few times when going around the corner that I had the impression that the source of the noise moved from the right side to the left. I suspect perhaps a loose crankshaft pulley, a slipping alternator belt, perhaps an engine mount, the transmission shifting is smooth and positive and the problem is ther in all gear positions. Your opinion appreciated...thanks
  • Correct the year of this geo to 1997 LSI Auto Trans..thanks
  • dan967dan967 Posts: 3
    Hi,
    I have a Chevrolet Geo Metro sedane, 1,3 ltr, 1997 and I have this problem :
    Sometime when outside is very hot, durring the summer time, and I drive slowly(trafic) the rpm decreases and the engine stop. When I start again the engine, that run perfect another 30 seconds and after this the problem start again. My mechanic scan the engine and find evrything perfect. No Error code. I already chek the EGR valve, the catalizator and the IDLE control solenoid, and all this is perfect.
    Can somebody help me, please?
  • dan967dan967 Posts: 3
    Hi,
    I have a Chevrolet Geo Metro sedane, 1,3 ltr, 1997 and I have this problem :
    Sometime when outside is very hot, durring the summer time, and I drive slowly(trafic) the rpm decreases and the engine stop. When I start again the engine, that run perfect another 30 seconds and after this the problem start again. My mechanic scan the engine and find evrything perfect. No Error code. I already chek the EGR valve, the catalizator and the IDLE control solenoid, and all this is perfect.
    Can somebody help me, please?
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