Susie Posted May 17, 2009 Share Posted May 17, 2009 Hello again! I posted about a week or so ago asking about my 2001 Forester. I followed the suggestions that I received here and replace my spark plug wires with ‘official’ Subaru wires. However, I’m still having a problem and today my car left me sit. To refresh your memories – 2001 Subaru Forester 140,000 miles Recently replace Timing Belt and Water pump (about 3000 miles ago) Replaced plugs and now wires Replaced Fuel Filter Added Fuel Injector Cleaner Replaced Air Filter Automatic No overheating No Check Engine Light Car has been running rough intermittently. Original thread - http://www.ultimatesubaru.org/forum/showthread.php?t=98920 I replaced wires last night and while it is too early to be sure, I think they might have fixed the rough idle problem. But today for the first time, my car left me sit. I was going up a mountain road which was about 2 miles long. About 3/4 up the mountain, my car suddenly started losing power. It didn’t matter if I gave it less gas or more, it had little to no power. I also tried to shift to a lower gear but it didn’t make any difference. While I was trying to move forward, the engine backfired about three times (this is the first that it has ever done that). I did manage to pull over to the side and sit for about 10 minutes with the engine off. When I started it up again, it ran perfectly fine. While I was sitting, there was a very strong odor of something running very hot. The temperature gauge was normal, no check engine light, etc. Does anyone have any idea what this new problem might be? Looking forward to hearing back from you guys – thanks so much! Susie Quote Link to comment Share on other sites More sharing options...
davebugs Posted May 17, 2009 Share Posted May 17, 2009 Other than the backfire it could be the alternator. You seem to loose the ability to do higher RPM's as the battery keeps de-charging. If the battery is good setting for a little while will rejuvinate it - for a while until you run it down again. First time it happened to me on a Suby I was replacing the fuel filter and stuff like that thinking it was RPM related (and the associated fuel needed form the pump, through the filter, etc.) But I've never had it cause a backfire. I'm amazed by the weird problems caused on Suby's by alternators - and how they seem to often need alternators. Someitmes it causes the ABS and another light (I forget) to come on apparently due to the low power. Quote Link to comment Share on other sites More sharing options...
Scoobywagon Posted May 17, 2009 Share Posted May 17, 2009 I suspect low coolant leading to an overheating condition. Might want to check into that. Quote Link to comment Share on other sites More sharing options...
Cougar Posted May 17, 2009 Share Posted May 17, 2009 My first thought on this problem is a faulty fuel pump. They can act the way you stated. A lean fuel/air ratio will make the engine backfire. Going up hills can make the engine sputter. Be sure the fuel pump relay is good also. Quote Link to comment Share on other sites More sharing options...
jmorton822 Posted May 17, 2009 Share Posted May 17, 2009 Sounds like your engine may not last very much longer without a lot of work. Let me know what you find out. I know of a 98 that used to do similar things and the dealer couldn't figure it out. Quote Link to comment Share on other sites More sharing options...
unibrook Posted May 18, 2009 Share Posted May 18, 2009 Has the front 02 sensor been replaced within the last 40k miles? If not, try that. Report back here. Quote Link to comment Share on other sites More sharing options...
Susie Posted June 8, 2009 Author Share Posted June 8, 2009 unibrook, I think you might have hit the nail on the head. My Check Engine light FINALLY decided to light and it is the O2 sensor. THANK YOU so much!!! I don't know why it took so long to come on and I don't know why it came on when it did because the engine was running perfectly fine. In any case, I'm so happy to know what the problem is and to know that I won't have to take out a mortgage on my car to fix it! Thanks to all for your help! Susie Quote Link to comment Share on other sites More sharing options...
idosubaru Posted June 8, 2009 Share Posted June 8, 2009 O2 sensors rarely cause a no start condition, so i'm not sure that will fix your issue. it might be more likely that the actual issue caused a mixture problem, triggering the O2 sensor code. that being said - this is a simple problem if everything you tell us is true: tune up done, car runs fine with no issues (when it runs), and the timing belt has been replaced. there are a lot of suggestions being thrown out here, all of which i doubt you can spend time on. if it has issues again we need to know a couple things to narrow this down without throwing parts/time at it: does it have good spark at all 4 cylinders? is it getting fuel? with the strong noticeable smell of something running hot that could mean the catalytic converter is hosed. or it could just mean axle grease or a drip of oil hit the exhaust which doesn't really mean anything or cause any problems. Quote Link to comment Share on other sites More sharing options...
Susie Posted June 10, 2009 Author Share Posted June 10, 2009 I've never had a problem with it not starting. The problem is always while running where it will just seem to lose power occasionally. This past weekend is the first time that the Check Engine light came on although I've been having this problem for the last month or so. I don't have the exact code from the Check Engine light but the guy at the parts store said that it is either the O2 sensor or a fuel pressure problem. I thought the codes were supposed to identify the exact problem and not give you more than one thing to check on. But at least it gives us an idea of where to look. My ex-bil set up a fuel pressure gauge so that I can watch that to see if that may be the problem. But with troubleshooting, the biggest problem is that it isn't consistent and I can't make it happen. Thanks so much for all your help, Susie Quote Link to comment Share on other sites More sharing options...
idosubaru Posted June 10, 2009 Share Posted June 10, 2009 I don't have the exact code from the Check Engine light but the guy at the parts store said that it is either the O2 sensor or a fuel pressure problem. your best bet is to get the exact code and relay it to us. the parts store guys can really be hit or miss. they see all sorts of different makes, models, and countless different engines, it is not likely they are very familiar with subarus - if that familiar with cars at all. i can appear psychic to folks about subarus. but folks come to me with other cars andi get it wrong all the time! engines are dynamic. "a code" doesn't necessarily mean "a fault". a signal out of range causes the check engine light. there are typically multiple causes for a signal to be out of range. a sensor not working - or not plugged in may cause the same fault. one means the sensor is bad, the other means the connector is bad, but the code is the same. extrapolate that to all sorts of possibilities and you begin to see the scope of the design. Quote Link to comment Share on other sites More sharing options...
Qman Posted June 10, 2009 Share Posted June 10, 2009 Stumbling, rough idle, sparatic condition are symptoms of a dirty or failing MAF or MAP. It could even be as easy as an intermittent vacuum leak. Does the power loss ever happen at other times other than up hill? Could be as suggested earlier as a failing catalytic converter. Quote Link to comment Share on other sites More sharing options...
Cougar Posted June 10, 2009 Share Posted June 10, 2009 If the fault code you are getting is due to a lean fuel mixture check the intake manifold gaskets for a possible leak. As was stated earlier, error codes can indicate a problem with the sensor involved or the circuit to it but they also can be triggered by other problems, like a air leak in the intake or exhaust manifolds. There are no codes for those things specifically. Problems like these need to be diagnosed properly before work is done so extra repair time and needless parts replacement dosen't happen. Good techs are still needed and also why they deserve a good salary to earn a decent living. Quote Link to comment Share on other sites More sharing options...
Susie Posted June 10, 2009 Author Share Posted June 10, 2009 Well, as luck would have it, my Check Engine light is no longer on. And to be honest, at this point, I don't know if that is good or bad! :-\ Can they still read the code off the computer or has it been cleared now that the light went out? Susie Quote Link to comment Share on other sites More sharing options...
idosubaru Posted June 10, 2009 Share Posted June 10, 2009 Well, as luck would have it, my Check Engine light is no longer on. And to be honest, at this point, I don't know if that is good or bad! :-\ Can they still read the code off the computer or has it been cleared now that the light went out? Susie - the older vehicles had a read memory mode, which would tell you all codes that were set at some point (since last cleared). I can't imagine the newer models don't have that functionality as well since the ECU's are far more modern and capable. Funny, I have a scanner, I've just never had to read a code from memory on a newer vehicle so i'm not sure. Hundreds of folks on here know the answer to that hopefully they'll pipe up. If you can - you'll want to pull those codes from memory and let us know what they are. post the exact codes - not what someone else thinks they mean. Quote Link to comment Share on other sites More sharing options...
welly Posted June 12, 2009 Share Posted June 12, 2009 Even with the CEL out the car will still store the fault code that triggered it. Any OBD II reader will get it for you. Quote Link to comment Share on other sites More sharing options...
johnceggleston Posted June 12, 2009 Share Posted June 12, 2009 the code will be there for a while, not for ever. at some point the computer will clear the memory. i don't know how long or what may trigger it. Quote Link to comment Share on other sites More sharing options...
Susie Posted June 13, 2009 Author Share Posted June 13, 2009 Hi guys - The codes from the Check Engine Light are P0172 and P0483. I understand that 483 is possibly low coolant but the radiator was full to the very top. I did add some 50/50 to the reservoir because I know that I have a small leak so I usually try to keep the resevoir from being completely empty. My ex-brother-in-law did install a fuel pressure guage but it hasn't shown any problem with the fuel pressure. Of course, the car has been running just fine and hasn't going into one of its no power fits. We're hoping that it will soon so I can watch the fuel pressure but in my vast mechanical knowledge () I don't think that is the problem. Thanks to all who have posted and helped me with my car!!! Susie Quote Link to comment Share on other sites More sharing options...
idosubaru Posted June 14, 2009 Share Posted June 14, 2009 Hi guys - The codes from the Check Engine Light are P0172 Awesome, thanks Susie for the info. You'll want to probably replace the O2 sensor. There are other things this could be, but i've seen this before on Foresters of this vintage. if you're around 100,000 miles, that's about the expected useful life of an O2 sensor anyway, it's usually the front that needs replaced. a bad MAF sensor is another possibility. O2 sensors are really hard to diagnose. O2 sensor you would want to buy new, preferrably from Subaru. MAF sensors fail so infrequently that used is the way to go with those. they're like $400 from a dealer or $25-$50 from a yard - buying two is better than one new one. both of these are really easy to replace and only take about 10 minutes. Quote Link to comment Share on other sites More sharing options...
edrach Posted June 14, 2009 Share Posted June 14, 2009 I'm with gg; get the exact posts and report back. Just as a guess, I'm thinking MAF or the connector/wiring going to it. An MAF failure causes it to go into "limp mode" so you can get it off the road and go short distances. Limp mode defaults the fuel mixture to rich so it runs and will not damage the engine due to a lean mixture. Rich mixture could also cause the backfire with a hot catalytic converter (which is what your CC will be after travelling uphill for two miles). Quote Link to comment Share on other sites More sharing options...
Cougar Posted June 14, 2009 Share Posted June 14, 2009 Here is what the codes mean. Code P0172 indicates that the fuel mixture is too rich in bank 1 (cylinder 1) side. Code P0483 indicates the fan performance is not correct. There may be a problem with the MAF causing the rich fuel mixture. The fuel pressure regulator may be causing the trouble also. Cleaning the MAF sensor may help solve the trouble. The fan performance may be due to a bad power connection to fan from the relay. The fan operation needs to be checked at least. Quote Link to comment Share on other sites More sharing options...
edrach Posted June 15, 2009 Share Posted June 15, 2009 From my limited understanding the front O2 sensor actually will try to influence the fuel mixture. The rear one only measures that the emissions are okay (this is the one that will fail you on an emissions test). Oddly, some people have been known to replace the rear one with a resistor to get through an emissions test. Odd that the rich mixture only occurs on one cylinder or bank. I'd think fuel injector problems for that (or the connector to the fuel injector). Let us know what finally resolved the issue for you. Quote Link to comment Share on other sites More sharing options...
Cougar Posted June 15, 2009 Share Posted June 15, 2009 The term Bank 1 is just refering to the side of the engine that has cylinder #1. I'm not sure if the engine refered to here has a bank 2 side and O2 sensors for it also. There may be just the one side. If the engine has multipoint injection it is possible that one of the injectors is leaking. Quote Link to comment Share on other sites More sharing options...
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