Last post on Nov 27, 2013 at 12:52 PM
You are in the Chevrolet Metro/Geo Metro
What is this discussion about?
Geo Metro, Chevrolet Metro, Hatchback
#1843 of 1867 Re: Geo-metro '98 5 speed w Carb 1.0 [tvmogul]
Mar 24, 2012 (1:59 pm)
Yeah; I have several other tried and tested ideas; but they largely go against your ideas. If you have enough trust to consider them; it will be to your benefit.
1> Your '98 Metro is not a Geo Metro; it is a Chevy Metro. General Motors sold the Suzuki built Metro under the Geo brand from 1989 to 1997; but they changed the name of the car to Chevy Metro in 1998, and it remained a Chevy Metro from 1998 through 2001, when it was last sold. The 1.0 liter motor was last sold in 2000. The importance of this is that if a parts clerk looks under Geo for parts for a 1998 model; they won't find any listings.
2> Like many other owners; you have mistaken the throttle body fuel injection unit on your car for a carb. Metros never had a carb. The fuel injection throttle body just looks like a carb; but if you take it apart; you'll find that there is no choke, no accelerator pump, no float, no jets, no power valve, and there is an electronically driven fuel injector hanging down in the center of the throttle body.
3> If your main bearing really was loose enough to cause the Crankshaft Position Sensor to not function; it would be making enough noise to be heard two blocks away. I assure you that this is NOT a main bearing problem.
4> There have been reports from other '98 Metro owners of problems that seemed to come from a bad crank position sensor. But the real cause turned out to be that this sensor is mounted in the oil pan; and there are aftermarket oil pan gaskets available (probably listed only for Geo Metros; which do not have a crank position sensor) which are significantly thicker than the original part. If the oil pan gasket is replaced with a thicker part; it will move the crank position sensor further from the crank than it was designed to be. And this will cause the sensor to not function at low RPMs.
5> Please have a cylinder compression test run on this motor. The normal compression pressure on this motor is 195 psi. The minimum allowable compression is 165 psi. If the compression on your motor is less than 165; or if there is more than 25 psi difference between any 2 cylinder pressures; the motor will not be able to run properly; and would need to be overhauled or replaced. If your motor passes a compression test; DO NOT change to heavier oil. It will compromise the lubrication at start up; which is the most critical time of all. 10W-30 is the heaviest oil to safely use in this motor.
5> Another issue which will cause this motor to cut out on re-acceleration is spark plugs which have worn to the point where the gap has become too large. The best choice for spark plugs in this motor is Autolite #XP63 or #AP63. The plug gap should be .043". Be very careful if you check the gap on the XP63 plug; the Iridium center electrode is brittle and will break easily if you put any pressure on it.
6> A distributor cap or rotor which has become dirty on the inside or outside will cause the motor to cut out on acceleration. So will a distributor cap in which the carbon button in the center has fallen out or worn away.
7> Spark plug cables which have developed excessive resistance (more than 1,000 ohms per inch of wire length) will also cause this problem.
8> If someone has moved the distributor position; in an ill advised effort to change the timing; it could cause this problem. The ignition timing cannot be adjusted on this motor; but moving the distributor position will change the rotor air gap; which will cause the motor to cut out on acceleration.
#1844 of 1867 Re: Geo-metro '98 5 speed w Carb 1.0 [zaken1]
Mar 24, 2012 (2:42 pm)
First off - let me thank you for your thorough response - it's great to finally get to chat with somebody who clearly knows this vehicle.
Ok so let me give you a few new details and maybe ask a few questions:
The spark plugs are new (with the last month or so-maybe 1000 miles)
Distributor cap has been checked and is perfect (button and contacts are fine)
Oil Pan Gasket is original and has never been off
Except for the time it cuts out (which is on re-acceleration in 5th gear AFTER being forced to slow in traffic) - it runs smooth as glass so would that not eliminate most of those other issues? (ie spark plugs, distributor cap)
It only seems to do it when the engine oil is hot, not the water (which always stays correct), just the oil itself - after the car has been running for a while.
I guess what I am asking is, if those above mentioned options were the issue, wouldn't the car run poorly all of the time and not just in this one, rare instance?
#1845 of 1867 Re: Geo-metro '98 5 speed w Carb 1.0 [tvmogul]
Mar 24, 2012 (4:08 pm)
Thank you, for your open minded, intelligent, and cooperative reply.
We can obviously rule out the pan gasket and distributor cap as a factor here. But the remaining items I listed are still very likely. To understand this; you need to know that this motor is extremely different in the way it runs from probably most of the motors you've experienced in the past. Japanese motors in general; and this one much more so that the rest, typically do not show signs of degradation in performance as they become worn. The only signs of poor compression will be apparent at low RPMs; particularly during the transition from deceleration to open throttle. This is an especially vulnerable area; because the computer cuts off the fuel injection during deceleration, and then turns it back on when the throttle is reopened. Because of the fuel cut circuit; the engine will be slightly starved for fuel during the first moments after the throttle is reopened; and the higher the gear being used at that time; the greater the load the engine will have to overcome; and thus the greater the tendency to hesitate or stall. This is why you experience this only in 5th gear. At what speed do you encounter this? I ask because some people are not sensitive to when this motor is being lugged. It should never be driven slower than 45 mph in 5th gear. If you coast down to 35 mph in 5th, and then try to accelerate; that alone could cause this, on an engine in perfect condition.
Cultivate the habit of downshifting to 4th whenever your speed drops below 45, and see whether this problem goes away. Downshift again to 3rd when your speed drops below 35 mph; and your little car will be far less likely to burn the valves; which is the downfall of so many mistreated Metros.
This amazingly responsive and economical car is far too highly tuned for the American public. And that's why it got such a bad reputation with insensitive drivers.
But as the valves burn, and the compression drops; the engine speed at which this problem manifests will become higher and higher.
If your car stalls out on transition from decel to open throttle at 45 mph or higher in 5th; then there is a mechanical problem. Low compression is the most likely cause. Poor ignition is the second most likely cause. NGK spark plugs just don't do the job in this motor; even the recommended heat range runs too cold. Autolites are the best thermal match to this motor. Excessively resistive plug wires, or wires which are not fully inserted in the cap or coil sockets; or plug boots which are damaged or are arcing will also do this. So will a low quality distributor cap. I spent years searching for a decent distributor cap for these motors; until I discovered by accident that Standard Motor Products #JH165T (their economy line) is a better quality cap than the so called premium quality caps. You need a cap with tan or brown insulation. The black caps don't hold up in this motor. Beck Arnley #1746959 looks to be another cap with better insulating material; but I have not used one personally.
If this problem manifests with proper driving techniques; please run a compression test on all cylinders, write down the measured pressures, and post the results here. Also tell me the brand and part number of the spark plugs in this motor. And I'll respond in kind.
#1846 of 1867 Re: Geo-metro '98 5 speed w Carb 1.0 [zaken1]
Mar 27, 2012 (6:03 pm)
Ok I will run the compression test and get you the info on the plugs and dist cap - in the meantime, lets just assume that it is the compression problem that you stated - since it's not a giant problem currently - let's assume I did nothing and waited until it became a real issue ... how long do you think this engine will last?
#1847 of 1867 Re: Geo-metro '98 5 speed w Carb 1.0 [tvmogul]
Mar 27, 2012 (6:15 pm)
It would be inaccurate and unnecessary for me to guess about the life expectancy of an engine that I have no details about. Since you said you'll run a compression test; it would be far more useful if I answered that question after seeing the numbers in the test results. It would be even more helpful if you were able to provide information about how far you can drive before the motor needs a quart of oil, following an oil change.
#1848 of 1867 Re: Geo-metro '98 5 speed w Carb 1.0 [zaken1]
Mar 27, 2012 (6:37 pm)
Ok - will do - may take me a few days to run the test but I will do it and get you the results.
And to answer your oil question - I change it every 2000 miles and have never had any issue of burning oil. I put in almost 4 qts and drain near the exact same amount.
#1849 of 1867 Re: Geo-metro '98 5 speed w Carb 1.0 [tvmogul]
Mar 27, 2012 (10:29 pm)
Your oil consumption report looks very encouraging. I am now having second thoughts about the cause of this problem. I may be able to save you from going through the bother of a compression test, if you can give me some additional information. Do you have access to a volt/ohmmeter? If you do, there are some measurements I'd like you to make. At this time, I would also like to know the details about the brand and part number of the spark plugs now in the motor. If you can also measure the gap; it would be that much more helpful. If you would prefer to not do these things yourself, but would instead have them done by a shop; I can provide a list of instructions to relay to the shop. But the procedures will not be excessively fussy. I just need someone to do them.
#1850 of 1867 Re: '91 geo metro ignition timing [zaken1]
May 01, 2012 (12:47 am)
Sorry, have to disagree with part of this:
The truth is that the Chevy Sprint engine had hemispherical combustion chambers and a single overhead camshaft; which operated two rows of adjustable rocker arms through solid lifters. That motor had a recommended valve adjustment interval of 30,000 miles. But the Sprint had a bad cylinder head design, and developed a reputation for blowing head gaskets.
Suzuki either couldn't, or wouldn't, fix the head gasket problem; so GM got their engineers to redesign the head. The head design was changed from a hemi head with two rows of adjustable rocker arms and mechanical valve lifters; to a wedge head with a single row of non-adjustable rocker arms and automatically adjusting hydraulic valve lifters.
The Sprint does indeed have the adjustable rocker arms, but you will not find a single lifter anywhere. The Metro does indeed have the hydraulic lifters, but zero rocker arms...
I do know this for fact as I have done a fair amount of work on both vehicles.
#1851 of 1867 Re: '91 geo metro ignition timing [sprinter4]
May 01, 2012 (1:57 pm)
You are absolutely right about this. It has been a while since I was into a Chevy Sprint motor; and when I thought of the design, the image of a solid cam follower came to mind. That was not correct. The Sprint rocker arms run directly on the cam lobes.
#1852 of 1867 Geo Metro 1997-Lack of charge.
May 31, 2012 (7:39 pm)
I have a 1997 GeoMetro and the past two years I have been having trouble figuring out why it wont charge the battery. I have bought a new battery and changed the alternator, but still dies with in minutes.
I had a few people check the car and the only thing they can tell me is that the alternator is bad. I gone to other places to check the alternator and they say its good.
Someone told me that maybe something is left on when the car turns off. Everything turns off when the car is off, however it had a added alarm that I wasnt aware of. My dad decided to disconnected and after a few months it drain the battery again.
Someone checked it and said it wasnt disconnected all the way and completely disconnected the alarm. We tried the car again and it ran for a few days and now its dead again and have to recharge the car.
I want to know what else could be the problem and how to fix it.