howards11 Posted May 10, 2009 Share Posted May 10, 2009 (edited) I am having an engine problem with my 2000 Forester L, AT, 70.2K mi. Once in a while the engine backfires. Not a loud backfire but a muffled one. Also periodically the car hesitates when I start from a light or stop sign. This started a few weeks ago. I thought it was bad gas so I refilled with 93 octane and added a bottle of dry gas. The problem disappeared. I thought that due to the temperature variation around here that I might have picked up some moisture in the system. The other day I refilled with Sunoco 94 octane and the problem is back again. I might have refilled at the same station where I did when the problem first started. Stupid me. Maybe it could be a partly clogged gas filer? There is no active CEL and these problems do not happen all the time. Anyone have suggestions ? This is driving me really nuts. Maybe a partly clogged gas filer? HELP !!!!!!!! ~Howard Edited May 10, 2009 by howards11 Link to comment Share on other sites More sharing options...
idosubaru Posted May 10, 2009 Share Posted May 10, 2009 any maintenance history at all? Link to comment Share on other sites More sharing options...
howards11 Posted May 10, 2009 Author Share Posted May 10, 2009 any maintenance history at all? 60K I had all the belts changed. Plugs changed about 2 yrs ago. June 2008 the coil pack went. The coil pack was replaced along with the spark plug wires. December 2008 the cat was replaced along with both O2 sensors. Car receives oil change every 3 months or so. ~Howard Link to comment Share on other sites More sharing options...
idosubaru Posted May 10, 2009 Share Posted May 10, 2009 if the plug wires weren't Subaru that could be the problem. EJ engines (yours) are kind of annoying with wires, they don't do well with any aftermarkets. if they weren't Subaru you might want to replace them. i've seen brand new aftermarket wires cause hesitation. and for the future, OEM NGK plugs too are best on these engines. Link to comment Share on other sites More sharing options...
howards11 Posted May 10, 2009 Author Share Posted May 10, 2009 (edited) if the plug wires weren't Subaru that could be the problem. EJ engines (yours) are kind of annoying with wires, they don't do well with any aftermarkets. if they weren't Subaru you might want to replace them. i've seen brand new aftermarket wires cause hesitation. and for the future, OEM NGK plugs too are best on these engines. Wires were changed with original Subaru. NGK plugs were used. The original plugs were Champion. US plugs in a Japanese care made in Japan. Should I try some fuel injector cleaner or some Seafoam? I think I'm going to pick up 3M Professional Fuel Injector Cleaner and try that. ~Howard Edited May 10, 2009 by howards11 Link to comment Share on other sites More sharing options...
idosubaru Posted May 10, 2009 Share Posted May 10, 2009 Air filiter, PCV valve, fuel filter? Those ever been replaced? Link to comment Share on other sites More sharing options...
howards11 Posted May 10, 2009 Author Share Posted May 10, 2009 Air filiter, PCV valve, fuel filter? Those ever been replaced? Air filter last spring. PCV valve and fuel filter both about 2 yrs ago. All my cars are well maintained. ~Howard Link to comment Share on other sites More sharing options...
howards11 Posted May 10, 2009 Author Share Posted May 10, 2009 A friend suggested that my problems could be the muffler since they are generating no codes. ~Howard Link to comment Share on other sites More sharing options...
Cougar Posted May 10, 2009 Share Posted May 10, 2009 The throttle position sensor may be developing a dead spot. Link to comment Share on other sites More sharing options...
howards11 Posted May 10, 2009 Author Share Posted May 10, 2009 The throttle position sensor may be developing a dead spot. COUGAR: How much does it cost to replace this sensor ? Would this problem produce a CEL code ? ~Howard Link to comment Share on other sites More sharing options...
idosubaru Posted May 10, 2009 Share Posted May 10, 2009 most problems produce a CEL - but there are rare ocassions where for some reason you don't get a CEL. they are very annoying, but i've seen it happen to MAF sensors, crank sensors, O2 sensors, and TPS sensors...so i'm fairly confident just about any sensor can havea problem without actually triggering the CEL. rare, but it's definitely possible. the TPS actually has moving parts inside of it, so it's a good guess. Link to comment Share on other sites More sharing options...
howards11 Posted May 11, 2009 Author Share Posted May 11, 2009 (edited) most problems produce a CEL - but there are rare ocassions where for some reason you don't get a CEL. they are very annoying, but i've seen it happen to MAF sensors, crank sensors, O2 sensors, and TPS sensors...so i'm fairly confident just about any sensor can havea problem without actually triggering the CEL. rare, but it's definitely possible. the TPS actually has moving parts inside of it, so it's a good guess. I added some fuel system cleaner (I think it might have been Valvoline brand) and the problems have stopped. I'm going to run this tank with the cleaner to almost empty and see what happens. ~Howard Edited May 12, 2009 by howards11 Link to comment Share on other sites More sharing options...
humbleninja10 Posted May 12, 2009 Share Posted May 12, 2009 First off hi to all, this is my first post. I like this idea of an all subaru model forum instead of a model specific, I mean if there was ever a manufacturer that interchainged its parts, but i digress. My susgestion would be to go to your local dealer and see if there are any ECU reflashes available that haven't been performed on your car. I know for the USDM foresters there is a reflash for this problem (hesitation, stalling and afterfireing, as subaru puts it), it usually requers replacement of the front A/F sensor, but you said it was recently replaced. And it seems to me that I've been doing more of these reflashes in the spring and fall when our gas seems to change, anyway hope it works out. Link to comment Share on other sites More sharing options...
idosubaru Posted May 12, 2009 Share Posted May 12, 2009 wow, if the cleaner worked i'd try some different gas (if you always use the same place), replace the fuel filter, and try some seafoam in the following tanks. wow - ECU reflashes, havent' heard much about those. interesting indeed, i'm utterly curious about what is being changed/updated. Link to comment Share on other sites More sharing options...
howards11 Posted May 12, 2009 Author Share Posted May 12, 2009 First off hi to all, this is my first post. I like this idea of an all subaru model forum instead of a model specific, I mean if there was ever a manufacturer that interchainged its parts, but i digress. My susgestion would be to go to your local dealer and see if there are any ECU reflashes available that haven't been performed on your car. I know for the USDM foresters there is a reflash for this problem (hesitation, stalling and afterfireing, as subaru puts it), it usually requers replacement of the front A/F sensor, but you said it was recently replaced. And it seems to me that I've been doing more of these reflashes in the spring and fall when our gas seems to change, anyway hope it works out. WOW...that's the first I'm hearing of this. I wonder if SOA customer service would know anything about this problem. ~Howard Link to comment Share on other sites More sharing options...
howards11 Posted May 13, 2009 Author Share Posted May 13, 2009 First off hi to all, this is my first post. I like this idea of an all subaru model forum instead of a model specific, I mean if there was ever a manufacturer that interchainged its parts, but i digress. My susgestion would be to go to your local dealer and see if there are any ECU reflashes available that haven't been performed on your car. I know for the USDM foresters there is a reflash for this problem (hesitation, stalling and afterfireing, as subaru puts it), it usually requers replacement of the front A/F sensor, but you said it was recently replaced. And it seems to me that I've been doing more of these reflashes in the spring and fall when our gas seems to change, anyway hope it works out. Received from Subaru of America (SOA): "Thank you for contacting Subaru of America, Inc. I'm sorry to hear of your vehicle concern with your 2000 Subaru Forester. According to our record for the VIN that you provided, your vehicle is not affected by any open recalls or campaigns at this time. Unfortunately, we are not equipped to diagnose your vehicle vie email or the phone. Instead we rely on the factory-trained technicians at authorized Subaru dealers in order to diagnose and repair Subaru vehicles. We suggest that you have your vehicle looked at by an authorized Subaru dealer in your area. Best Wishes." Now what ? ~Howard Link to comment Share on other sites More sharing options...
idosubaru Posted May 14, 2009 Share Posted May 14, 2009 (edited) with no CEL or more information i don't know what to tell you. personally i'd start swapping parts - TPS, MAF, ignition coil, CAS, cam sensors, etc but i have the luxury of having one or 5:lol: of everything lying around. or get it over with and take it to a dealer. at some point you reach a limit where being resourceful, DIY, or cheap on such a new and valuable vehicle doesn't make sense. any number of sensors, wiring, fuel pump..... Edited May 14, 2009 by grossgary Link to comment Share on other sites More sharing options...
howards11 Posted May 14, 2009 Author Share Posted May 14, 2009 with no CEL or more information i don't know what to tell you. personally i'd start swapping parts - TPS, MAF, ignition coil, CAS, cam sensors, etc but i have the luxury of having one or 5:lol: of everything lying around. or get it over with and take it to a dealer. at some point you reach a limit where being resourceful, DIY, or cheap on such a new and valuable vehicle doesn't make sense. any number of sensors, wiring, fuel pump..... Now the problem has gone away. Go figure. I'm just going to keep a check on it and see what happens. Maybe the fuel system cleaner had some effect. With my next batch of gas I'm going to add some Seafoam and my at next oil change I'm going to have the gas filter and the air filter changed. ~Howard Link to comment Share on other sites More sharing options...
howards11 Posted May 17, 2009 Author Share Posted May 17, 2009 Problem is back again. I think I heard it backfire today. I'm not sure. There was too much talking coming from the backseat. I am sure it hesitated a few times. Plus my wide felt it hesitate too. I'm going to call my mechanic Monday and see what he says. He has connections at the nearby Subaru dealership so maybe they can help him diagnose this strange problem. This problem has been going on since the switchover to summer gas. ~Howard Link to comment Share on other sites More sharing options...
johnceggleston Posted May 17, 2009 Share Posted May 17, 2009 have you tried higher octane gas? with prices still sorta low it might be worth a try. i thought back fires were a timing iossue. Link to comment Share on other sites More sharing options...
howards11 Posted May 17, 2009 Author Share Posted May 17, 2009 (edited) have you tried higher octane gas? with prices still sorta low it might be worth a try. i thought back fires were a timing iossue. For the last several weeks since this problem developed I've been using 94 octane Sunoco or 93 octane Shell. The last tank was Shell plus a bottle of Chevron Fuel System cleaner. I think it's time my mechanic and I had a talk about how to handle this problem. You are correct about backfiring being a timing problem but here is an oddity. There are no CEL codes being generated. The backfiring seems really muffled and does not happen all the time. The hesitation does not happen all the time either. Someone said it could be (check the thread) the throttle position sensor which has developed "blind spot" or perhaps the ECU needs to be updated. Maybe I should bring this to a Subaru dealer? Anyone have a good dealer in the Philadelphia, PA area? I'm not that far from Glansmann Subaru. My mechanic has contacts at Colonial Subaru. Plus there is Reedman-Toll Subaru not too far from where I'm located. SOA was no help on this matter. Sorry for being long winded on this issue. ~Howard Edited May 17, 2009 by howards11 Link to comment Share on other sites More sharing options...
Cougar Posted May 17, 2009 Share Posted May 17, 2009 The problem may be due to a faulty CAS sensor or possibly the CAM sensor. Some folks have fixed this sort of trouble replacing them. Checking the signals with a scope may show up something. Link to comment Share on other sites More sharing options...
howards11 Posted May 17, 2009 Author Share Posted May 17, 2009 The problem may be due to a faulty CAS sensor or possibly the CAM sensor. Some folks have fixed this sort of trouble replacing them. Checking the signals with a scope may show up something. COUGAR: I appreciate your suggestions. Could you please tell me what is a CAS sensor and what is a CAM sensor. ~Howard Link to comment Share on other sites More sharing options...
Cougar Posted May 17, 2009 Share Posted May 17, 2009 COUGAR: I appreciate your suggestions. Could you please tell me what is a CAS sensor and what is a CAM sensor. ~Howard A CAS sensor is a crank angle sensor and a CAM sensor is a cam angle sensor. Link to comment Share on other sites More sharing options...
howards11 Posted May 23, 2009 Author Share Posted May 23, 2009 (edited) I took the Forester to my mechanic the other day. He tried to see if there were any codes and there were none. He could not make the car hesitate. He did tell me to stop using 93 octane gas and go back to regular. :-\ He did tell me it could be the MAF sensor but he really was not sure. I had him change the air filter and the fuel filter just to be on the safe side. Today is the Friday before Memorial Day and I was off from work. I drove the car around more than usual. It still hesitates at times. This evening even my wife who was sitting up front felt it. I was stopped for a light with the AC on when it happened. I went to my podiatrist today. He used to have a 2000 Forester. We talk cars and PC's as he works on my feet. He told me that he remembered having the ECU refreshed when he had the Forester. I am contacting the dealer my podiatrist uses and set up an appointment with them to look at my Forester. ~Howard Edited May 23, 2009 by howards11 Link to comment Share on other sites More sharing options...
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