Subaru Legacy/Outback Wagons Maintenance & Repair

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Comments

  • ladywclassladywclass Member Posts: 1,713
    I drive more like the men ... lol
  • paisanpaisan Member Posts: 21,181
    I know why it has slipped. Simple economics. Basically in any manufacturing situation, a company will look to cut corners any way they can. A simple $1 cut on a car can save them a lot of $. Basically as long as their sales are high, a company will cut corners. For instance, take the Trailblazer/Envoy topic in here. They have tons and tons of people complaining about the build quality (headliners falling, trim coming off, etc) but in most of the replies they end their complaint with "But I'd buy another in a heartbeat" To the manufacturers this signals "well it's ok to cut corners cause they'll still buy em"

    I think Honda and Toyota have been living on their reputations from the '80s and '90s and basically are riding out the wave of "well my '80s and '90s toyota/honda lasted 150K, so I'll buy another one" meanwhile they have cut costs.

    Just my thoughts on why they don't seem to last as long, at least a contributing factor.

    -mike
  • ateixeiraateixeira Member Posts: 72,587
    "at least 150K without problems"?

    Depends on how you define problems. Sorry, I don't intend to pull a Clinton here. :-)

    I'm just saying odds are pretty good you'll have at least several small problems by 150k, and possibly 1-2 big ones.

    The odds of zero problems for 150k are maybe 10 to 1.

    Think about it - lots of folks change their water pump when they do the timing belt at 60k miles, because they're not expected to last 120k.

    Look at things like your CV boots - they are rubber, not some space age material that will last forever. After about 10 years, you can expect the rubber to start to rot and soon that grease will leak. Same with the axle boot. Radiators rust. The vinyl top on my Miata (straight A reliability for 13 years) cracked because the vinyl is old and brittle.

    You might consider those wear and tear items, and if so that's a little more believable. I guess you could say "no major mechanical failures for 150k miles" and I'd agree.

    It's not like Honda or Toyota invented a special rubber that lasts forever.

    -juice
  • idahodougidahodoug Member Posts: 537
    I have worked as a Product Planner (the folks who decide all the aspects of the cars you drive) for GM and Toyota/Lexus. I don't have the CR issue, but if the main conclusion is that an 8 year old Asian vehicle (they must have lumped the lower quality Korean vehicles with the Japanese??) is as reliable as an American vehicle only half its age, I'd agree. Personally, I feel the gap is even wider than that - in favor of the Japanese.

    Did the Japanese invent a "special rubber that lasts twice as long"? Unequivocally, yes. There are small decisions made at each step in the process and the Japanese make the nod in the direction of quality. In rubber alone, there are hundreds of grades, qualities and design differences.

    I think the question NYGREG asked above is highly relevant and really the key to the discussion. He asked what are these failures and is one companies "failures" comprised of a water pump where another's are engine main bearings that basically destroy the engine? I'd like to know that, also and presumably CR would tell us rather than lumping these as equivalent.

    We carried out extensive quality comparisons that basically had competitive vehicles driven around the clock until they accumulated 100k miles. Failures were noted. The data showed overwhelmingly that Japanese cars are FAR more durable and reliable than American cars. This data was collected by GM, by the way.....

    GM and American cars continue to get better, but the gap is tough to close.

    IdahoDoug
  • keithrichmondkeithrichmond Member Posts: 35
    Say, btw, my parents made it through the day yesterday with no problems (I'm cursing them by saying that though!).

    Of all the cars my family has taken to 200K none has gone there for free. Sure we pay a little here and a little there, but my beef is that for a car that is 3 years old to start dropping $2k per problem is counter to our previous experiences.

    My dad's 'charter owner' '86 Acura was an incredible car until '95, when just at 200K everything started failing at once. Their '87 Pontiac wagon never really 'died' like that in 1999 - they just started having too many overheating problems to feel comfortable driving it any more. I guess that's the Asia/US difference. As another point of reference, I just sold my '77 BMW 320i last fall. It was a one-owner prior to me and it was still running completely untouched (mechanically) 25 years and 175K miles later. I drove the snot out of it without putting anything more than a $12 thermostat in it during my tenure with it. Of course the rear strut towers rusted out completely, but the guy that bought it from me drove it from DC to NC in one shot and it turned into a donor car for him. That's reliability.

    keith
  • fibber2fibber2 Member Posts: 3,786
    OK, your report raises many interesting questions. Japanese automakers have been able to maintain their quality levels despite the sharp rise in domestic content (ie North American parts sourcing) and US assembly. Yes, it is down a bit from JDM levels, but still a far cry better than traditional US makes. This suggests that GM should be able to get equivilent quality components as their competition. And with their buying power, should be able to get high quality components for less. So why is there still such a gap?

    Steve
  • wmiller4wmiller4 Member Posts: 97
    Bucking and Sputtering.........maybe a bad fuel injector?

    Just my .02 cents.
  • paisanpaisan Member Posts: 21,181
    My personal feeling is that in non-us run plants (be them in the US or outside the us) the management has a different mission/attitude that is filtered down to the workers on the line. This also combined with maybe tighter tolerances on the non-us manufacturer lines? Certainly seems odd that even US-built Foreign vehicles have a better reliability. Design might also come into play, for instance the Trailblazer/Envoy rear folding seats fold down and the flip-cover on the centere console power outlet rubs against the folded seat, causing them to eventually wear pre-maturely, non-attention to detail seems more prevelant in US vehicles...

    -mike
  • lark6lark6 Member Posts: 2,565
    paisan: Best post I've seen from you in a long time. ;-)

    I think labor/management relations have a lot to do with product and service quality in everything we buy. I also think it has to come from more than just an attitude or message that gets filtered down to the rank and file. Companies have to invest in the line worker, show them they are more than an interchangeable piece of meat and an important part in the success of the company. The existence and influence of labor unions in the US has had a mixed bag of results in that area.

    Engineering and design tolerances are obviously a key factor as well. Some manufacturers, for example, place a heavy value on getting switchgear to move in ways to please consumers' senses of touch and sound.

    Steve's post about the ability to obtain raw materials of equivalent quality at lower cost also raises the possibility that maybe GM doesn't care about getting those materials. It's that concept of planned obsolescence, taken to extremes.

    Ed
  • ateixeiraateixeira Member Posts: 72,587
    But Doug, cost-cutting has run rampant. Look at Nissan, where it's most evident. Do you think the new Altima has the same quality materials as the last one?

    Heck, the CEO is nicknamed Carlos "le cost cutter" Ghosn. And it's not unique to Nissan, they've all been cutting costs, including Subaru (just read a press release where they mentioned it, ugh).

    Keith: I agree. A $2k problem is serious. But I do think that one or two $700 problems is perfectly normal after 5-7 years. Heck our 626 had 5 such problems in 7 years, and it's rated as reliable.

    As for import/domestic, two good examples are Mazda and Mitsubishi. Mitsu has taken a nose dive since they have more and more in common with Chrysler. Mazda too, by using Ford parts and even sharing platforms (Tribute is easily their least reliable vehicle).

    But look at the Miata - built in Japan and all aces in reliability. So Mazda still has the ability. Their philosophy isn't the problem. It might be the "lowest bidder" philosophy that Ford and Chrysler have.

    Someone comes in a bids a cheapo widget at 2 cents less than quality widget, and the bean counters calculate the volume and decide they'll "save" big money due to volume.

    Then the cheap widget breaks or warps or fades or squeeks or rattles, gets recalled, and generally turns away buyers. Have you seen how much market share GM has lost?

    Ed reminds me of what Hyundai did to the Canadian plant, they shuttered it and left the community unemployed and with big debts.

    -juice
  • ateixeiraateixeira Member Posts: 72,587
    Example of cost cutting: the new Civic has already had 6 recalls, same as the Focus.

    The Focus is veiwed as a very low quality vehicle, but somehow the Civic has a good enough rep that people give it the benefit of the doubt.

    But you really think a Civic that had 6 problems out of the gate will have ZERO problems for the next 10 years? Doubtful.

    -juice
  • nygregnygreg Member Posts: 1,936
    You can cut costs and still keep quality high. In fact, efficiency (and in my mind simplicity) does both. I agree that management style and decision plays a key role. Case in point - you know about the sludge issue with some Toyotas. Small percentage - but within months Toyota fixed it and gave all owners an 8 year, unlimited mileage warranty for sludge. This definitely impacted some managers bottom line. Another manufacturer would look at what that would cost and compare it to what it would cost to fix the few engines and estimate how many customers they would lose to this problem and make a "lowest monetary impact" decision.

    Greg
  • roadrobertroadrobert Member Posts: 4
    I have a '99 L wagon (2.2L) that it is very difficult to read the oil level on the dipstick - I feel like a dipsh@*! It doesn't matter if
    the car has been sitting overnight and I just pull it out and look at it or if I wipe it, reinsert then pull out and read (cold, warm or
    hot)! The oil is above / below and all over the add / full marks on the dipstick (VERY FRUSTRATING...). I owned this car for over a year
    now and do my own oil changes, so I just make sure that I put "exactly" 4.2 quarts in then hope it doesn't burn or leak! Please advise, as I have owned many other make cars and NEVER had this problem... Thanks
  • mikenkmikenk Member Posts: 281
    Long term reliabilty is primarily influenced by the design process not manufacturing. Toyota and Honda have a totally different design process and philosophy than does American and European automakers. It is much more based on reuse and improvements of components than on top down styling. As a result, where the cars are built will have little impact on reliability, although it would impact the JD Powers type survey on initial quality.

    I am not familiar with the Subaru design process relative to Toyota and Honda, but I would guess it is similar.

    BTW, I agree that major car components should last upwards of 150 - 200k miles before failure; I expect that. Sure, there might be one or two isolated failures but not a systemic failure of lots of subsystems. That's poor design.

    Mike
  • ateixeiraateixeira Member Posts: 72,587
    I dunno, Toyota dragged their feet for a few months. They resisted as much as they could, but in the end the power of the internet and speed at which information travels overcame their denial.

    Perhaps the monetary impact was bigger because their reputation for reliability allows them to charge more for a Camry than most other cars in its class.

    -juice
  • idahodougidahodoug Member Posts: 537
    The question on why GM has not been able to match Japanese quality levels has more to do with their design and engineering process than with the availability or nonavailability of quality supplier parts. Quality comes from employees at all levels, the integrity of the process, the assembly plant and you multiply this times the number of suppliers involved - all of whom must also be on the quality bandwagon. I can't really answer the question here or I'd have War and Peace in a 40 character wide column...

    Robert, you're not alone with the 2.2 dipstick follies. My theory is that capillary action keeps the entire dipstick marked area wet even if it sits overnight. Here's the only way I've been able to get an accurate reading. When you get home for the night, open the hood and pull the dipstick. The next morning, insert the clean dipstick and you'll get one single accurate reading - reinsert and it will be screwed up again. It's the shape and location of the dipstick tube - maddening I know. On a trip, it works to a lesser degree if you immediately pull it and fill the car, clean the windows, pick your teeth and take a leak before checking the oil level.

    IdahoDoug
  • nygregnygreg Member Posts: 1,936
    Doug - like your idea. Sometimes I get a better reading when I rotate the stick around 180 degrees.

    Greg
  • keithrichmondkeithrichmond Member Posts: 35
    Here I was going to make this statement but mikenk said it for me:

    A well built car will survive the warranty period.

    A well designed car will survive 200K miles.

    keith (my shortest post yet!)
  • nygregnygreg Member Posts: 1,936
    Well said. I like!

    Greg
  • frankomafrankoma Member Posts: 4
    Both of the rear window switches in my '02 LL Bean pop right out of their sockets when you raise the window. I'm guessing there's a clip or maybe a screw that's missing that should hold these guys in place. Does anyone know what this part is?

    Frank
  • jfljfl Member Posts: 1,399
    Frank, won't your dealer take care of that?
  • ateixeiraateixeira Member Posts: 72,587
    I agree, well put Keith!

    I've never had the doors panels apart, sorry.

    -juice
  • nygregnygreg Member Posts: 1,936
    The cover on my hatch sometimes comes off, but that's it.

    Greg
  • daricedarice Member Posts: 4
    I have to vent here. I have 55,000 milies on my outback and have had to turn the rotors 3 times (under warrantee), then replaced (not under warantee) and now - 10,000 miles after replacement, they need turning again. What is the matter with my car?!?!?! This getting beyond ridiculous AND expensive. It is NOT my driving as the dealer would have me believe. ARGH! Is anyone else having this problem or my car possessed?
  • snowbeltersnowbelter Member Posts: 288
    I have an 02 VDC and have used premium gas (93) since I purchased my car one year ago. Now, with gas prices over $2 I've been thinking of switching to mid (89) or regular (87). I've read that some of you have switched with no problems. Anyone notice a decrease in gas mileage, and if so does the decrease negate your savings? The reason why I'm posting rather than just trying it myself is that the Service Manager at my dealer told me his experience is that I'll experience knocking, and that in order to switch back to premium, I'll need to bring my car in for an ECU reset. I thought using a lower octane gas would cause the timing to retard and that going back to the "good stuff" would cause the timing to advance, i.e. the timing would readjust by itself I called 1800Subaru to ask and was told that customer service had no technical expertise and could not ask someone on the technical side for an answer. They then read the owner's manual to me (premium is recommended).
  • idahodougidahodoug Member Posts: 537
    Snowbelter, you're correct. The engine will adapt to whatever fuel you put in it instantly. It will also adapt back to premium. Your dealer is full of malarky - ECU reset indeed. How much were they going to charge for that?

    On the brake poster, what year are you talking about?

    IdahoDoug
  • paisanpaisan Member Posts: 21,181
    My dad's '97 Legacy goes through pads every 10-12K miles. He probably needs rotors as well, very common on pre-2K outbacks/legacies.

    -mike
  • keithrichmondkeithrichmond Member Posts: 35
    Add 2 more data points:

    '95 Legacy wagon - eats pads and warps rotors like crazy ...thanks for reminding me what else I didn't like about that car! :)

    '00 Legacy GT wagon - solid brake performance - pads probably replaced twice - front rotors replaced last year - rears last month (115K miles)

    I'm guessing they changed something for the better.

    I've been reading about Bendix rotors being less hot spot-prone (the cause of warping) than some OEM rotors. No experience yet but when our Honda Odyssey needs new rotors I'll be trying them.
  • paisanpaisan Member Posts: 21,181
    For the most part you can buy performance rotors for roughly the price of OEM ones with significantly increased performance. That's what I would do when replacing them.

    -mike
  • fibber2fibber2 Member Posts: 3,786
    I don't own an H-6, but it will probably react much the same as my old Camry V6 did. While premium fuel is recommended, you are not really making use of the higher octane level in most driving situations. When you push the engine beyond what lower octane can provide in terms of anti-ping stability, the knock sensor should come into play. As you said, the timing will be retarded until the ping subsides, then the timing will slowly be advanced until ping returns, or normal timing is reached without ping. The net is that HP levels will be slightly reduced. If it has to run this way a lot, you may see a slight decrease in MPG, but in most seasons it will not be enough to offset the fuel price savings.

    I used to run regular in cooler weather and was rarely aware of the timing retard. But due to higher heat loads and A/C, I was acutely aware that the knock sensor was overactive in the warmer weather and went back to premium.

    In the event your car reacts badly to the change in fuel, an ECU reset might be in order. But this is something you can do yourself. I believe the basic procedure is to disconnect the negative battery terminal on a cold engine for a half hour or so. Reconnect and start the engine. Let it idle until it comes up to full temperature. Drive away slowly, then resume normal driving practices for a few miles. The ECU should learn and adapt to the new conditions of driving style and fuel octane capabilities.

    Crew - Did I leave anything out?

    BTW, where in NY??

    Steve
  • ateixeiraateixeira Member Posts: 72,587
    darice: at this point I would go with new, aftermarket rotors. You're paying for it anyway, see what kind of warranty those options offer.

    paisan beat me to it.

    FWIW, I have the original pads and shoes on my '98 Forester after 50k miles.

    -juice
  • toboggantoboggan Member Posts: 283
    At 53,000+ miles on original pads and rotors on my '98 OBW Limited. Just changed out the winter tires for the summer tires. Looks like the pads are good for another 50K miles. Of course I have the 5spd and use compression braking a lot.

    MNSteve - Whee, the snow is almost gone - Spring!!!!
  • daricedarice Member Posts: 4
    Thanks for all your input on my brake issue. It's a 2001 Outback - any suggestions on a brand name for a performance rotor? Should I go elsewhere than the subaru dealer for this?
  • cptpltcptplt Member Posts: 1,075
    I've never had a problem with excessive wear/rotor problems on 2 92s or my 98!
  • idahodougidahodoug Member Posts: 537
    Just a point of order on the above comment that ECU reset will help with ping management by the knock sensor. Completely untrue and wildly speculative.

    The knock sensor is designed to instantly respond to what the engine is doing. It is specifically designed to handle transitional (a few seconds worth) pinging and return to normal operation, and merely reacts to a tank of low octane fuel by doing nothing - until pinging occurs. Then it goes back to normal operation.

    The knock sensor does not acquire a "memory" or get "stuck" in low octane mode and resetting the ECU will not impact it at all. Use the logic test on it. Would it make sense to have a system that slowly retarded the timing more and more and stayed in that mode when there is no reason? Of course not. The whole point of electronics is that they can respond instantly to transitional conditions, adapting to the moment to prevent engine damage while maximizing performance.

    IdahoDoug
  • fibber2fibber2 Member Posts: 3,786
    Why do you insist on answering a query with a not so friendly 'both feet first' approach? Do you really think that tone adds anything to the dialog?

    In the interest of brevity I glossed over some of the facts and speculations, so let me try this again. Disclaimer: No two mfgrs systems are the same, and they are constantly evolving with time. This is my understanding of how things can work. It may not fit with what you think you may know from your experiences at GM. And I admit that I don't know Subaru specifically, so all of the data may not fit here either. However, I am basing the knock discussion on some previous threads that involved factory people from Subaru dealing with a customer complaint on excessive knock. This involved ECU reprogramming by the factory to address some engine knock tendency that was outside of the 'ability to learn' parameters in the current mapping. Plus my own experience on the subject.

    A knock sensor is simply one of some two dozen plus input parameters that the ECU takes into consideration. Knock sensors don't get "stuck", they just report the news as it happens. Programmed into the operating firmware (software probably contained in EPROM) is a 3D contour map that governs system operation. All of these sensors act like 'hands' on the side of a Oujiy board, moving the action point along the hills and valleys of this map. The map has certain built in biases, which limit how much influence any of these 'hands' can have on the map in any given situation. Some of these maps are adaptive - they can 'learn', or shift slightly with repeated inputs. The most obvious example: automatic transmission shift points.

    So will a sudden change in knock rep rate cause a lasting change in map parameters, or only a momentary action with no global impact? In short, will the engine adapt, or is intervention in order? I am not really sure. But what her dealer suggested, IIRC, is consistent with factory action to a specific complaints on this board about 18 months ago. Try an ECU reset, and see if the knock will go away. Some reported an instant change. Sometimes it stayed gone, sometimes it returned in a week or so. Some had to have their ECU 'reprogrammed' - a permanent 'shift' to the program.

    BTW, I had the same problem with my '00 Ford Windstar (3.8L V6). When excessive knock occurred, I would drive in to Colonial Ford. They would do a powered ECU reset (no charge), and I would drive away ping free for a couple of months. I had to do this twice before it stayed quiet.

    And sensors are not perfect - they change values with time. The ECU will take the revised values as valid and respond accordingly until the parameters shift outside of the action limits. That's when you are most likely to get a CEL and the system will log an error. Most typical to have this type of soft failure are things like oxygen sensors.

    Steve
  • ateixeiraateixeira Member Posts: 72,587
    darice: call Tire Rack to get price quotes on brake kits that'll fit your Outback. Maybe just the rotors, I'm sure the calipers are fine.

    Anyone else suggest a spefic brand or vendor for our colleague?

    I think places like Midas advertise lifetime brakes, but they might milk you up front for those.

    -juice
  • zman3zman3 Member Posts: 857
    I thought it was just me that was reading a certain "tone" into IdahoDoug's comments. Glad it's not just me.

    IdahoDoug, you're proving to be a great resource I just think you ought to be more careful with the wording sometimes. Some of us seem to be inferring a tone.

    Take care.
  • snowbeltersnowbelter Member Posts: 288
    Life with cars was much simpler before they came with ECU's which cause disagreements over ECU resets. SOA who built the car with "premium recommended" and put in the ECU has the expertise to answer this question, but as I said SOA Customer Service "punted" when I spoke to them. Check out Chat Transcript dated 4/18/02 with Rick Rhoades SOA Technical Service Instructor. "[Regular gas] won't hurt. 92 octane is recommended. With lower octane, you might not enjoy the performance your car was designed for". Now, he doesn't say whether or not you may need an ECU reset if your car becomes very unhappy with regular. Steve, you asked my whereabouts. Feel free to email me.
  • idahodougidahodoug Member Posts: 537
    First off, nice overview of engine management electronics, Fibber. Good show and well stated.

    Secondly, I agree with both you and Zman - I tend to be brief and to the point and I accept your criticisms. I approach cars from a fairly technical background and sometimes it manifests itself in a less than personable approach. Also a symptom of owning and operating two companies - not a good excuse since everyone's busy these days, eh?

    FWIW, my experience is not only limited to being a former Product Planner at GM. I was also Worldwide Powertrain Planner at GM before leaving for Toyota and Lexus. Now I own a company that does product training for Mazda, Lincoln-Mercury, Toyota, Isuzu, Hyundai and others. So I have a fairly broad knowledge of what the various manufacturers are up to. In many cases, I think it would be safe to say that my background in vehicle systems may exceed that of a typical factory rep.

    The ECU reset issue has been all over this board as a panacea for everything from stalling to pinging. Basically, this temporarily wipes out the adaptive aspects of the engine management system and returns things to factory default values. When you restart, this often means the timing is retarded (sorry, PC would be "developmentally challenged") and everything's in the 'safe' zone. Thus no ping. But the owner is not getting full performance or efficiency out of the engine until a map as you described gets rebuilt atop the factory presets and the engine moves toward more performance. True to form, if there's an issue causing ping it will begin pinging again and the knock sensor will pull the timing back in response in a constant cycle. No real gain is achieved, and during the rebuilding process you're spending more fuel money and running with less power.

    The correct way to react to ping in my book would be to determine the reason and fix it. The most likely scenario in today's high tech engine would be the vehicle has been run on cheap offbrand fuel often enough that deposits have formed in the cylinders. I'm surprised at the number of people who pay $25,000 for a car and put junk gas in it to save $75/year (10 cents/gal X 750 gals/year).
     
    Today's engines are running very close to max timing in order to burn all the fuel for emissions and to provide maximal horsepower. Electronics allow manufacturers to let the engine's timing dance right at the edge of ping all the time, so we're seeing more and more complaints about ping from every manufacturer.

    To avoid this if you have it, I'd first try a quality fuel additive like Techron Concentrate (not regular Techron). Then use quality fuel, and put premium in every few tanks. It only takes a small amount of cylinder deposits to turn an engine designed to run on the ragged edge into a ping machine. Don't use cheap gas - you'll pay for it eventually when the engine loses efficiency.

    Here's an industry secret for you, BTW. Many manufacturers require premium fuel simply because they know it will reduce the number of warranty issues because it is better for the engine. Premium fuels are higher quality and better for the entire fuel system, cylinder environment and even the emissions and exhaust - including the famous oxygen sensor. Yes, some do it so they can add 7hp to their engine rating, but many are after the lower warranty costs and higher customer satisfaction premium fuel produces.

    At any rate, thanks for the input on my tone. As a final comment so you'll know I'm not such a bad guy, I'll try to garner some pity from you guys in that my sweet wife and darling kids have been in Vail on a ski trip for 10 days and I miss them and am probably grouchy. Then, the storm hit Denver and they've been snowed in in Vail for 4 more days and I can't take it any more. Just me and the cats. They're going to try to get out tomorrow morning and if they do I promise you won't see any more grumpy old man posts......

    Later,

    IdahoDoug
  • fibber2fibber2 Member Posts: 3,786
    We all have our 'days'! Hope everyone gets home soon, safe and sound. 'Nuff said....

    Back to the technical! We agree that a new map gets 'rebuilt' after an ECU reset. Correct me if I am wrong, but my understanding of adaptive management is that the new map may not be a 1:1 match of the map that was deleted. If that is the case, then a more pronounced input from the
    knock sensor (from a change to lower octane gas & ECU reset) might generate a slight shift in map contour during this 'rebuild' phase? Maybe providing a deeper or more prolonged timing retard, slightly richer mixture, delayed upshift, etc., during hard acceleration thereafter?

    Steve
  • zman3zman3 Member Posts: 857
    Believe me, I wasn't trying to attack you personally or imply you were a "bad guy". I thought maybe you were an engineer since I also tend to be a bit "brief and to the point."
      
    FWIW, I did infer a much different tone in your last response. Very informative too, by the way.
  • idahodougidahodoug Member Posts: 537
    Ahhhhh. The family is back, the house is again bustling and all is well here again. Whew.

    Thanks for the kind comments.

    Generally speaking, the knock sensor loop won't change after a reset. It is "dormant" until knock is sensed (more on this later) and then goes through a standard ritual of timing retarding, and then continues "listening" for more knock. If none is detected, some systems will advance a bit until knock is detected, others will stay retarded for a few minutes to be sure the added heat in the cylinder from knock is dissipated. Depends on the "aggressiveness" of the software and there are a lot of variations.

    But their is generally no interface between an ECU reset and the knock loop. The knock loop focuses completely on instant adjustments to the timing no matter what else is going on with regard to the map. Wouldn't matter if the ECU has just been reset and is running on the defaults, or if the map has been refined over tens of thousands of miles.

    If, say, the mfr decided that the knock loop's first response would be to retard timing by 4 degrees, it would not matter if the ECU was running off the defaults or the refined map - the timing's coming back 4 degrees. I don't even think the knock loop will "know" what the base timing is as this is irrelevent to a certain degree. It doesn't care if the knock is because someone put cheap gas in, or a teenager is learning to drive a manual and is flooring it from rest in 3rd gear - it will quickly retard timing based on the cylinder environment until no knock is detected.

    Knock detection took a big leap forward a few years back with the introduction of piezoelectric sensors embedded in the block. Basically, these are vibration detectors, and they use vibration as a proxy for knocking. Knocking is simply pre-ignition and causes the block to vibrate in a way that is abnormal. Many V6 and V8 engines will have one in each cylinder bank for precise detection. In so doing, knock sensors can detect knock below the threshold of a driver's ability to hear it if the mfr chooses to be that aggressive with knock management.

    The next generation is said to be a pressure sensitive sensor in each cylinder's head. Kinda like the move from fuel injected (single injector for all cylinders into intake manifold) to MPFI which puts an injector in each cylinder. That will allow for even more precise knock control and our kids will probably never even get to hear what it sounds like.

    IdahoDoug
  • fibber2fibber2 Member Posts: 3,786
    because I am an engineer & very stubborn!

    I agree - the knock loop response to an event (and return to the current value) is fixed. ==> A retard of X amount from the current value (what ever that is), then return. But it is the starting point, or 'current value' itself that's in question. As we both have stated, this began as a basic programmed lookup table, then was refined from maybe thousands of miles of driving. This new value will not change appreciably or quickly in response to a single event.

    The initial factory defaults may have had a fairly conservative spark timing profile. With time, the advance curves were refined, assuming the ECU rarely registered a knock event. Now something radical changes - tanks of cheap gas. The knock sensor goes into hyperactivity. The standard spark retard cycle comes into play very often. If this becomes a continuous event, a true 'learning / adaptive' system should begin the slow task of rewriting the 3D map to accommodate the new conditions, offering less advance for a given set of driving conditions.

    The idea of the ECU reset quickens the task. Back to the milder factory defaults, and a fresh rebuild of the maps using the 'new' real world conditions of more easily induced ping from cheap gas. It might not be the best approach, but the new map should have advance curves that are different from the previously created set.

    Some of the lab equipment I am familiar with use 'learning lens tables' to do a similiar function. They will adapt slowly on their own to changing conditions, or can be forced into a more rapid global reset and relearn. The software exists - just a matter of whether the automakers have adopted it.

    Steve
  • paisanpaisan Member Posts: 21,181
    I'd rather replace pads than either a clutch or tranny. So I'll hammer the brakes before using engine braking unless it's in inclement weather or hilly terrain where brakes could overheat.

    -mike
  • toboggantoboggan Member Posts: 283
    A combination of both is actually used. I've been using a MT in a variety of vehicles for 45 years and never had to replace a clutch plate or rebuild an gearbox. Whoops, forgot the MK. I Austin-Healy 3000 (Colorado Red). That had a weak first gear. Put in a new 1st gear cluster and Corvette clutch disk.

    MNSteve
  • shlossershlosser Member Posts: 4
    I have a 1991 Legacy L wagon and the passenger side front axle started to catch and make a grinding noise. I just went back to school and money is tight so I took the front right axle out and started looking for a used one. Evidently my car made in 11/90 has a maverick axle assembley only used for a few months. I do not really need the AWD. I have driven the car around town here for a couple of weeks and the only odd symptom is a sensation like the clutch is slipping on hard acceleration.The car has 241,000 miles on it and has never faltered except for a timing belt. Can I just drive it this way ? Thanks for any input
  • idahodougidahodoug Member Posts: 537
    Steve,

    I agree with you on the milder factory presets - that would be logical and typical for the industry. Over time, the cylinder environment will determine the map's parameters and each engine varies a bit in terms of its optimal operation (cam grind, various mfg tolerances, altitude, etc). As it ages, more changes occur that the ECU can adapt to. FYI, most current vehicles also interface with the auto tranny and adapt to the aging of the tranny by moving shift points, line pressures, etc to keep shifting smooth over the miles.

    So, I think we agree on the basic working parameters, but differ on the benefits of the ECU reset in terms of controlling knock. I feel the ECU reset causes the engine to operate inefficiently for at least as long as it would take for the engine to adapt to transient knock conditions of cheap gas, a trip to the mountains, etc. Without specific knowledge of Subaru's logic circuits (time to respond, % change of the response, etc) I'd enter into the speculation arena now that we've taken the discussion up to this level as to the system response. Most systems are similar these days, but each manufacturer has their own beliefs and preferences.

    If I personally began experiencing knock, I'd look for what has changed (needs plugs, bought cheap gas in a hurry, etc) and change it. I'd also consider the Techron to reduce deposits in the cylinder environment - THE major culprit to knock after cheap gas.

    Shlosser,

    Is this a manual, or automatic?

    IdahoDoug
  • fibber2fibber2 Member Posts: 3,786
    Who's there? Two engineers who have finally come to a meeting of the minds about knock!

    Seriously, Doug - excellent discussion. It took a few days, but I think we covered a lot of ground. I understand your point about not jumping to do an ECU reset without giving due thought as to the reason why, and the consequences of your action. Hope others on the sidelines got something from the exchange.

    Question for you. Considering how often batteries are disconnected for servicing the vehicle, or get run down by accident, why would a mfgr leave the ECU maps in volatile memory (requiring keep alive power) rather than write them into flash or other static media? I had never heard of 'user resets' before coming to this board. Is this a universal method, or do some require an active clearing by diagnostic computer interface?

    Steve
  • keithrichmondkeithrichmond Member Posts: 35
    My parents are returning home from their Florida trip today. They've been telling me the CEL comes on, goes off, etc during the trip but there is no noticeable problems so they keep on running.

    I'll be putting in a new front O2 sensor per this boards' recommendations and see how it goes. I can't see why they would want to replace 2 cats when they aren't running rough or anything.

    Oh, and I should do a 'hard' ECU reset, correct?

    keith
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