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| Big emissions problems on my '90 Geo Metro | |
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| Tweet Topic Started: Jun 16 2010, 09:21 AM (4,797 Views) | |
| alivedw | Jun 16 2010, 08:17 PM Post #16 |
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New Member
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OK some updates for you all. 1) I'm buying a new cat. For $100 shipped it can't hurt. I suspect the cat has a lot to do with this problem, and even if it's not the sole source of the problem, gas mileage should improve. Thanks for that link, BadBent! 2) Bill CNC was right - my damn check engine light had burnt out. I can't believe it...why didn't I check that before??? As it turns out, the ECU is throwing 2 codes: 13 and 23 (or is it 32? hard to tell). I'm going to go on the Engine Codes post to see what these are and trouble shoot from there... You all are amazing. Wish me luck. Daniel |
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| mwebb | Jun 16 2010, 08:41 PM Post #17 |
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FOG
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key on engine off the check engine light should light up , when the engine is started , the CEL should go out , if all is well bulb check is a part of the system . ================================================== 3000 ppm HC is NOT a rich condition test result. high HC is caused by INcomplete combustion the High CO values ARE caused by rich condition OR the CAT is doing the best it can with the High HC DO NOT REPLACE THE CAT yet . because if you do without locating the problem , you will kill the new cat deader than dog poop . HC will be around 450 ppm if the cat is bad and there are no other problems ==================================================== the 02 sensor condition and output is very important when diagnosing this problem , you need to get a DVOM on it and you need to report the results should be switching between 150mv and 850mv very fast at 2k rpm hot , is it ? if the 02 sensor is NOT performing as designed , the CAT will be destroyed in short order - again DO NOT REPLACE THE CAT yet . because if you do without locating the problem , you will kill the new cat deader than dog poop . so as i see it your high HC is caused by misfire what is causing the misfire is the question intake vacuum Teed into MAP sensor vacuum line BEFORE the restriction orifice . intake vacuum at hot idle is ? MUST be 20" and there must be no Flutter in the needle ready begin said the sarcastic SOB |
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| bogs | Jun 16 2010, 10:11 PM Post #18 |
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Duct tape heals all wounds
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I swear I did NOT say that
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| Woodie | Jun 17 2010, 06:44 AM Post #19 |
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First off, stop with all the crazy fuel concoctions. If your engine is worn and very near passing the test, trying different fuel additives or adjusting the timing might help you get by until the next inspection before you have to do a rebuild. In this case, you're WAY off the mark, something is horribly wrong. High test is NEVER a good choice for emissions (or anything else) it burns slower than regular and is more likely to spew unburned fuel into the exhaust. Error code 13 is bad O2 sensor, that right there could be the entire problem. 23 is Intake Air Temperature, 32 is Manifold Absolute Pressure, doesn't matter which is which, either one could be the problem. The two of them occurring together tell me that you didn't reconnect your sensor ground wires underneath the intake manifold, very unlikely that two separate sensors have gone bad at once. First step of any emissions test is to turn the key on and look for a check engine light, if it doesn't light up, you go home. Of course this is not only government, it's DC Government, two distinct reasons to expect incompetence. |
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| crankcase | Jun 17 2010, 11:14 AM Post #20 |
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Woodie, I don't want to come accross as rude, but I don't follow you on this. What angle are you comming from, please exaplain? "High test is NEVER a good choice for emissions (or anything else) it burns slower than regular and is more likely to spew unburned fuel into the exhaust." By high test I assume you mean high octane? Doesn't high octane have LESS heavier gas/oils in it? It should also be less likely to ping (post ignition). From what I have read, high octane burns the best, most completly, and most efficiently of the octane grades commonly available. Edited by crankcase, Jun 17 2010, 11:21 AM.
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| mwebb | Jun 17 2010, 11:30 AM Post #21 |
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FOG
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Woodie is correct high test should really be labeled "mediocre test" it has less energy in BTUs and if used in an engine not designed for it it will leave deposits in the combustion chamber stock metros with stock compression ratios should only use 87 octane fuel |
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| crankcase | Jun 18 2010, 12:00 AM Post #22 |
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The determination of the octane rating for gasoline is complex. In short, high octane fuel has the highest flash point (resistance to going off by itself under compression) of the three common grades. Automobile emissions are somewhat complex as well. Factors that produce low nitrogen compounds don’t necessarily help reduce hydrocarbon emissions. There is no one "fixes-all" except to maybe to have all systems working correctly. It may be true that in general, high octane fuel may not help with hydrocarbon and carbon monoxide emission testing, although it is probably a benefit in the nitrogen compounds portion of the test due to possible higher combustion temperatures of low carbon fuels (short chain fuels i.e. methane burns bluer than higher carbon fuels such as diesel?). Common horse-sense causes me to have lingering doubts that extra load is placed on the engine due to some pre-detonation of the low carbon parts of the gasoline mixture. My pinging, old Ford truck sure made it up a steep hill easier where I lived when she was burning the expensive stuff. This was true in spite of how hard I pressed the peddle when she was burning the cheap stuff. The extra fuel had to go somewhere when using the cheap stuff, I guess it could have gone into the pinging, but my point is that an engine under extra load “SEEMS” to run a little dirtier. This truck (1994 B2300), though not in proper working order, ran better on high test. A high octane content only reduces the flash point of the fuel. In a sense, high octane fuel can be thought to burn slower than lower grades which contain more volatile constituents, but uncontrolled burning is a more correct description. There are arguments that this higher flash point/slower burning tendency leaves deposits. This is not a convincing argument to me (at this time) because, to my understanding, the “burning” refers to controlled ignition of the flame front versus uncontrolled ignition. The burn time should be about the same (or at least be completed by the end of the stroke for regular grade gasoline designed engines). I look forward to having this point made clearer. Gasoline is a complex mixture of hydrocarbons, with its main constituents being lower carbon fuels such as pentane and hexane, with only SMALL amounts of higher carbon, nonane fuel. What constitutes an ideal fuel for a gasoline engine not entirely straight forward. Roughly speaking, the standard is octane fuel, or better put, high octane fuel. Some newer gasoline engines aim to take advantage of higher compression ratios, and consequentially need higher octane fuel which is better able to cope with the higher compression. The lower octane fuels would not survive the compression encountered leading up to the point of ignition, and would tend to pre-detonate. The nature of fuels, engines, and engine efficiency is rooted in thermodynamics. A more efficient engine will have higher compression and higher cylinder operating temperature (more specifically, temperature differences with the outside environment). The diesel engine was designed with these facts in mind for high efficiency. Gasoline fuel could never reach the type of peak compression occurring in a diesel engine without spontaneously going off. Oily, high carbon fuels with high flash points that resist spontaneous combustion must be used in diesel type engines. The number of kinetic energy BTUs available from a fuel is really tied to the type of engine it is burned in (i.e. its aspiration, compression, compression ratio, operating temperature, coolant system etc.). Higher octane fuels may have slighter higher potential energy due to their longer carbon chain content, but the difference is basically insignificant. The retrievable potential energy stored in chemical bonds is dependent on how it is burned. For instance you can get a lot more energy from compressed diesel in an engine cylinder than burning it in an open, yellow, sooty flame. I was REALLY READY for a good debate about fuels, and was even feeling embarrassed to refute respected colleges, but for the most part, I was the one shot down in flames. So, I had to settle for a long winded reply instead. I got most of the info. for my little novel from a physicist/gear head friend of mine at Texas State University, and the rest came from the web. I will talk with others if there is anything new to add about the debate. Thanks to all of you for keeping it real. What big brother has to say about high octane fuels: http://www.ftc.gov/bcp/edu/pubs/consumer/autos/aut12.shtm Wikipedia on octane ratings: http://en.wikipedia.org/wiki/Octane_rating#Effects_of_octane_rating Article on pre and post ignition written by Allen W Cline designer of the Northstar engine http://www.944enhancement.com/html/knock_ping.html Edited by crankcase, Jun 18 2010, 01:19 PM.
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| Woodie | Jun 18 2010, 06:50 AM Post #23 |
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No, high test gas has chemicals added to it that make it less likely to light off, a side effect is that it burns slower. I've never heard of post-ignition, no idea what that is. The reason your Ford truck ran better on high test is that it was pinging in the first place. Any ping, knock, or detonation is lost power. Backing off the ignition timing by as little as one degree probably would have had the same effect as using the more expensive fuel. Just read the links you provided and found nothing but confirmation for what I said. The first one was the most concise when it started out like this: "Are you tempted to buy a high octane gasoline for your car because you want to improve its performance? If so, take note: the recommended gasoline for most cars is regular octane. In fact, in most cases, using a higher octane gasoline than your owner's manual recommends offers absolutely no benefit. It won't make your car perform better, go faster, get better mileage or run cleaner. Your best bet: listen to your owner's manual. The only time you might need to switch to a higher octane level is if your car engine knocks when you use the recommended fuel. This happens to a small percentage of cars." |
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| bogs | Jun 18 2010, 11:51 AM Post #24 |
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Duct tape heals all wounds
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Woodie, and nice set of links CC. Post ignition (I think) is describing when you turn your key 'off', and the car continues to fire. Much like pre-detonation, it is usually caused by fuel still being ignited in the cyl. It was a much larger problem back in the day.It could also mean this: "Post Ignition". A uncontrolled explosion after the ignition event. |
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| crankcase | Jun 18 2010, 12:28 PM Post #25 |
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The post-ignition is covered in the last link. It is where the charge starts a regular burn but then "explodes" in an unusual or uncontroled way after ignition has started. This is a different animal than pre-ignition (from what I have read, is also what's most commonly occuring when poeple report pinging). It is also called detonation in the link. The links were intended as you read them and just listed as references. I don't know what chemical addative you are talking about that cause slow burning, and as a reult deposits. I suppose it depends on what brand gas it is? I would like to know more about the slow burning/deposits you speak of. I have only seen that mentioned in forums such as this one. Please forgive me being a skeptic. It is just my understanding at this time is that, it may burn relatively slower, or perhaps better yet more controled, but ideally the engines are designed to burn the whole charge and get max power. An explosion vs a controled burn may be a fine line. It seems high octane ignitions would be closer to the ideal control burn for an engine designed to burn on regular. It makes sense that high octane motors need high octane fuel or damage will likely occur. It's not so clear that a regular octane designed engine would get fouled from high octane fuel. I mean no disrespect and I hope my ignorance will be excused; I would just like to be straight on the question. I will continue to dig myself, but if anyone has a link or reference that would be helpful, I would like to see it. Edited by crankcase, Jun 18 2010, 12:42 PM.
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| mwebb | Jun 18 2010, 11:00 PM Post #26 |
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FOG
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from the link select "gasoline" and "all properties" http://www.afdc.energy.gov/afdc/fuels/properties.html Gasoline Chemical Structure C4 to C12 Cetane Number N/A Pump Octane Number [1] 84-93 (c) Main Fuel Source Crude Oil Energy Content (Lower Heating Value) 116,090 Btu/gal (g) Energy Content (Higher Heating Value) 124,340 Btu/gal (g) Energy Contained in Various Alternative Fuels as Compared to One Gallon of Gasoline [2] 100% Physical State Liquid the "high" value in BTUs is for the lower octane fuel the "low" value in BTUs if for higher octane fuel the concepts and questions you ask are common knowledge in the automotive repair community , i will see if i can locate a few links in the meantime JOIN IATn search in the TTF for posts by Kevin McCarthy. the answers to your questions are there |
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| Woodie | Jun 19 2010, 06:27 AM Post #27 |
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Used to be Tetra-Ethyl Lead. That poisoned catalytic converters so they use something else now. You can buy octane enhancers in the auto parts store that you simply pour into the tank to raise octane, same thing the fuel company does except their tank is bigger. Ever wonder why a Metro's exhaust is so sooty? Inside of an exhaust pipe should look light gray and ashy, but on a Metro, black crumbly soot is normal. That's because the engine was designed to run with 10° advance. When the Federal government followed California's lead to limit NOx emissions, Suzuki added EGR and retarded the timing to 5° advance. Now the valve opens before the burn is complete and burning fuel/air mix rushes by the exhaust valve, raising it's temperature drastically and turning into soot in the exhaust system (and EGR ports). Advancing the ignition timing reduces this effect, putting in slower burning gas will increase it. |
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| mwebb | Jun 19 2010, 07:50 PM Post #28 |
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FOG
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...." Ever wonder why a Metro's exhaust is so sooty? Inside of an exhaust pipe should look light gray and ashy, but on a Metro, black crumbly soot is normal. ".... i just this minute went out side and wiped my finger in the tail pipe of the metro and the audi and the VW and sable only the metro had slight black buildup that may be described as very fine and light soot the other cars had zero deposits of any kind in the tail pipes interesting ... what does it mean ? my metro is running right at about zero trim adjustment at cruise but very slightly subtracting . 5% or less the metro is also the only one with TBI and the most primitive system by far out in my driveway - i had attributed the soot observed by others to be boiled out deposits from the crap oil they are using , which will also clog up EGR passages , a good reason to never use ILSAC GF4 , API SM non synthetic oil s in the engine . but my metro has just a wee bit of the soot deposits and i use ACEA A3 B3 - B4 0w30 . so it's not from the oil the only other choice is carbon deposits from Incomplete combustion .... and that sux - That's because the engine was designed to run with 10° advance. When the Federal government followed California's lead to limit NOx emissions, Suzuki added EGR and retarded the timing to 5° advance. Now the valve opens before the burn is complete and burning fuel/air mix rushes by the exhaust valve, raising it's temperature drastically and turning into soot in the exhaust system (and EGR ports). Advancing the ignition timing reduces this effect, putting in slower burning gas will increase it.".... 10 degrees 5 degrees ... that is base ignition timing . but depending on the software in the ECM base timing is only where the calculation begins , the actual timing is far more advanced driving at cruise and peak combustion pressure should be happening at about 10 to 15 degrees ATDC which is what the software should be designed to provide . and why the ECM advances actual timing from base timing during operation . any deviation of base ignition timing that changes peak combustion pressure timing from 10 to 15 degrees ATDC is going to be bad in my special car --- advancing base ignition timing past about 10 degrees BTDC reduces FE , so in my car that must be also advancing peak combustion pressure timing outside of the optimum window of 10 to 15 degrees ATDC but while i was doing that failed experiment , i did not think to wipe my finger in the tail pipe to check for larger amounts of soot / carbon also since i have the 3tech +10 cam wheel , my exhaust valve is opening 10 degrees sooner , 10 degrees more advanced than a stock G10 engine oh shit ... i think i may need to switch back to the stock cam wheel timing for a bit to see what difference , if any , that would cause |
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| crankcase | Jun 20 2010, 08:01 PM Post #29 |
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I hope the OP is making progress. I still say it’s the cat or a MAP problem. Nice link mwebb. It is clear high carbon fuels can produce more potential BTUs if burned in such a way to get maximum energy. Since gasoline is not a homogenous fuel, maximum conditions cannot be met for each constituent of the mix. If a vehicle is not experiencing detonation - indeed - there is no evidence that any benefit will be gained from running high octane in a regular gasoline designed vehicle. At least no evidence I could find, I looked. Intuition tells me that some PARTIAL DETONATION could rob power and produce waste. But, this probably does not occur in a significant way, if at all, since detonation is associated with the piston/crank encountering harder opposition (in high gear, high manifold pressure, hard for the burning charge to deflect the pistons, reducing speed). In my State, emission testing is done parked in neutral and at low and then fast idles. There should be minimal tendency to detonate under these conditions. I stubbornly maintain that high test is good at inspection time and for more power, but I’m having to face the facts that this is only a feeling and there is not really any evidence for this, except where detonation is occurring. So far I have not seen any evidence other than hearsay that high octane fuel will actually foul an engine designed to run of regular gasoline. This seems to be tied to the idea of higher octane fuels being too slow burning, or have additives added, or both. Why would an agent be added only to “extra” (that has a tendency to foul) but not the other 2 grades that have the lower flash point in the first place? Is this something new associated with the high compression high octane designed engines? I would think more advanced valve systems would be the big factor in less soot in the exhaust. Do Metros uses base timing for idle/low RPM/low load conditions (grasping for proper terms here) and don’t affect advancing done by the ECU? Please correct my understanding that the advance set around 8 as opposed to 5 gives better fuel economy, more power, but dirtier emissions. Did earlier Metros and their G10s use the 10 degree advance before the clean emission drive? Engine optimization for power emissions and drivability and how these factors tie in to the basics of engine operations (timings, advance, fuels properties, and interactions of the various stages of mechanical advantage/simple machines etc.) is complex. Often what happens in one area cannot be taken out of context with what is happening in another. Thanks mwebb and woodie for your patientce and willingness to share (not to mention the "edumacation"). P.S. Here is another nice link on pre-ignition and detonation (albeit in aircraft engines). It is the best one I’ve seen so far on these muddy phenomena. http://www.avweb.com/news/pelican/182132-1.html |
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| Woodie | Jun 21 2010, 05:58 AM Post #30 |
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Advancing the ignition timing (up to a point) increases efficiency and performance in every way, including decreasing emissions in every way but one. The sole exception is NOx. Retarding the timing reduces NOx, but increases all other emissions. |
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Woodie, and nice set of links CC. Post ignition (I think) is describing when you turn your key 'off', and the car continues to fire. Much like pre-detonation, it is usually caused by fuel still being ignited in the cyl. It was a much larger problem back in the day.
7:39 PM Jul 10