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Car Forum / Subaru Cars / December 200896 legacy 0420 ideas..?
(6 legacy outback, 2.5, 160,000 miles, code for catalytic efficency... Fuel mileage doesn't seem too good, and am in process checking. The EGR valve diaphram doesn't move, so I suspect it needs replacing, the spark plugs have never been replaced as far as I know..., the tailpipe is black sooty, and the oxygen sensors may need replacing although there is no code. I was wondering if replacing the plugs, EGR, and oxygen sensors might prevent me from having to purchase new cats...?... Thanks R. > (6 legacy outback, 2.5, 160,000 miles, code for catalytic efficency... > Fuel mileage doesn't seem too good, and am in process checking. [quoted text clipped - 5 lines] > Thanks > R. I've heard that this code CAN be caused by bad O2 sensors. Certainly cheaper to replace them than the cats. But that wouldn't cause a sooty exhaust. You should replace the plugs anyways, especially if they are old. They probably aren't that efficient any longer especially if they are original. Dan D '99 Impreza 2.5 RS (son's) Central NJ USA >>(6 legacy outback, 2.5, 160,000 miles, code for catalytic efficency... >> Fuel mileage doesn't seem too good, and am in process checking. [quoted text clipped - 15 lines] > '99 Impreza 2.5 RS (son's) > Central NJ USA I agree with Dan. That is a lot of mileage and AT LEAST the front O2 sensor must be getting lazy/bad if it is original. If the car has been running poorly for some time - the cat con COULD be compromised, but, as said, being the most expensive Item, I'd only do it after addressing the other issues. I THINK your car had platinum plugs from the factory(might be the H6es only get those?). That might explain them lasting this long. You COULD save a little and go with copper this time - but platinum or iridium would probably last until the wheels fall off and changing plugs on these vehicles can be a challenge. Certainly if I were paying a shop $80/hr - I'd put in the iridiums I think. If I were set up to do all my own wrenching and didn't mind the work - put the copper in. More people have fixed the 420 code with o2 sensors I think than with converters! OEM sensors seem to be much preferred. Check some on-line dealers to save a little money, or at least ask your local dealer to match on-line pricing. (I've had good luck with Jamie at www.subarugenuineparts.com) Carl  Signatureto reply, change ( .not) to ( .net) I figured since it still ran like a scalded dog the cats were not clogged. And, with the EGR not pulling some N2O the O2 sensors might be feelin it. The plugs are gonna go platinum as original. I suspect they are the cause of the richness as well. It was driven by a little old lady before I bought it. She didn't have the service records. She did tell me it had been serviced well. By the way... are these cats 3 way or 2 way ? Do you know the original O2 sensor maker ? I'm planning on getting the EGR from genuinesubaruparts... Thanks guys >>>(6 legacy outback, 2.5, 160,000 miles, code for catalytic efficency... >>> Fuel mileage doesn't seem too good, and am in process checking. [quoted text clipped - 39 lines] > > Carl If you had bad plugs they would only cause the engine to miss, not burn rich. Plugs only need to be replaced if the engine is missing and it's the plugs fault and not something else. You don't need to replace plugs very often these days like the old days. More likely the o2 sensor telling it to burn rich. Sometimes a bad connection to it can also cause problem. Bob Noble http://www.sonic.net/bnoble >>>>(6 legacy outback, 2.5, 160,000 miles, code for catalytic efficency... >>>> Fuel mileage doesn't seem too good, and am in process checking. [quoted text clipped - 20 lines] >>> '99 Impreza 2.5 RS (son's) >>> Central NJ USA > I figured since it still ran like a scalded dog the cats were not clogged. > And, with the EGR not pulling some N2O the O2 sensors might be feelin it. [quoted text clipped - 49 lines] >> >>Carl Be sure to test the Engine Temp Sensor (not coolant gauge sender). It can sometimes fail in such a way to keep the ECU in 'choke' condition and may not throw a code. If poor maintenance is suspected - the brake fluid shouyld be flushed - it can have a lot of water in it. The tranny should be flushed or perhaps have 2-3 drain/fill cycles at least. The Tires MUST be the same model and wear, differences of 1/4" in CIRCUMFERENCE are discouraged by Subaru due to torque bind/center diff (or clutch pack) stress. Probably could use a coolant flush too. Be sure to search and read about 'burping' the coolant system. Probably needs a PCV valve as well. Might as well consider radiator cap and maybe thermostat. Um, do you know if the timing belt was changed? If you can't be certain, pull the covers and inspect it. Do that immediately. It would be a shame to get the other issues solved and throw a TB! Inspect all the axle boots for splits too. whew! Carl Signatureto reply, change ( .not) to ( .net) > > I figured since it still ran like a scalded dog the cats were not clogged. > > And, with the EGR not pulling some N2O the O2 sensors might be feelin it. [quoted text clipped - 74 lines] > -- > to reply, change ( .not) to ( .net) are you serious "differences of 1/4" in CIRCUMFERENCE" if the tire diameter is 24" then 24" * 3.14 = 75.36" 75.36" + .25" = 75.61" 75.61" / 3.14 = 24.079" so every tire has to be within .04" diameter of each other or each tread depth has to be within .02" of each other. how do you measure this? how do you make this stuff up? if you don't know the facts keep quiet. don't spew in accurate information. >>> I figured since it still ran like a scalded dog the cats were not clogged. >>>And, with the EGR not pulling some N2O the O2 sensors might be feelin it. [quoted text clipped - 85 lines] > if you don't know the facts keep quiet. > don't spew in accurate information. Ahem; ******4. Do I have to replace all four tires on my AWD Subaru? All of the tires on your AWD Subaru must be within 1/4 of an inch of rolling circumference (part that touches the road). This is because of our All Wheel Drive System. Proper rotation of the tires at the appropriate service intervals will increase the life expectancy of your tires. This will also ensure that all four tires stay relatively equal in their tire tread wear. When vehicles are serviced, tires should be routinely checked to ensure that the alignment and tires are in good working condition. ****** from;http://www.subaru.com/common/faq/tech_info.jsp#3 Carl Signatureto reply, change ( .not) to ( .net) > marc.wert.m...@gmail.com wrote: > [quoted text clipped - 108 lines] > -- > to reply, change ( .not) to ( .net) I sincerely apologize to the contributor who was quoting Subaru text. Unfortunately someone at Subaru pulled some numbers from the air or some where else and put it on a web site and now it is fact. I'm sorry but I cant believe even Subaru corporate cars have all their tires within this spec. >>marc.wert.m...@gmail.com wrote: >> [quoted text clipped - 114 lines] > sorry but I cant believe even Subaru corporate cars have all their > tires within this spec. Subaru may very well be encouraging rather strict adherence to tire wear/size parameters because they know that the reality folks will experience is greater than 1/4". However, Subaru is not the only maker of AWD cars and I suspect any AWD drive could experience damage if regularly operated on dry pavement with mixed size tires. Most systems will respond to an undersized tire as 'slippage' and could experience torque bind. If that stress is not relived, some drivetrain component will be damaged. There are various approaches to use of undersized tires. Some cars with open front and rear diffs might be able to put new tires on one side for instance.(limited slip rear diffs would preclude that approach). Some folks can find shops that will shave a new tire down to mix in with older tires. Generally, the savings from having 2 tires treated that way would make buying 4 new tires a better choice overall. Rotate your tires and make sure you understand what your manual says about use of spare tires and emergency towing, etc. High/special performance cars often require special care in one or more areas. Subaru AWD needs the tires to be the same size. How far you can deviate from that and not experience drivetrain problems? .. who knows? Too many other factors to consider. If you frequently drive on gravel, dirt or wet surfaces and make lots of turns - there's plenty of opportunity for any binding to relieve itself. If you drive many miles on staright, dry highways - you could significantly shorten the life of your center diff/wet clutchpack or other drivetrain component. Carl Signatureto reply, change ( .not) to ( .net) > > I sincerely apologize to the contributor who was quoting Subaru text. > > Unfortunately someone at Subaru pulled some numbers from the air or [quoted text clipped - 31 lines] > > Carl Carl, you're right, Audi has the same spec with the quattro system. However, in general, as long as the tires on the same axle are within spec, you're okay. You generally don't need to replace all 4. Dan D '99 Impreza 2.5 RS (son's) '04 Audi A4 1.8T quattro 6-speed (mine's ;-) Central NJ USA |
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