beeemveek1 Posted April 6, 2013 Share Posted April 6, 2013 Hi everyone. I'm new to this forum and hope you all could give me so thoughts regarding my car's persistent problem(s). It used to be my daily driver but with the problems it's no long fun and questionably safe. 2003 GT wagon with a 5 spd 104K mi all stock; no modification upgrades other than Enkies and had good Michellins Been an absolute joy and incredibly fun car to drive since. It may not have the acceleration but it sure can handle the curves. I think in real world road i.e. bad pavements potholes, ruts, etc. there's nothing better than the long suspension travel and the LSD of the GT Subies. Car has been meticulously maintained w/ synthetic oil every 5 kmi and diff every 30 kmi, and filters, plugs, wire, etc... About 10kmi ago, the car would exhibited a subtle hesitation or misfire like jerkiness with light throttle input around the residential neighborhood (20-25 mph). Strangely the symptom only started after I filled up the gas tank. Normal acceleration and all other engine performance was normal. If the car sat (cooled down) after a few hours, the hesitation went away. The was consistent and repeatable. I tired new plugs, plug wires, air filters, fuel filters. The hesitation became more pronounced as the mileage increased. About 6kmi ago, a new problem started: Sudden deceleration from freeway speed with the clutch depressed and brakes applied the engine idle stalls and sometimes would die (cut out). Luckily I was able to bump start the motor with the clutch. So I brought the car in to a local Subie specialist. Check engine light (CEL) would repeated only provide a general error code according to tech. Over the span of about a year ..... Subsequent attempted fixes included: the fuel filter replaced, both the 2nd idle and then the primary idle controller replaced, throttle body cleaning. I have tried new plugs and new wires. The Subie specialist who I have complete confidence in and wholeheartedly trust reported that he honestly does not know the cause and has suggested maybe a reflash of the stock ECU. Now before I proceed with the ECU reflash.... My thoughts (I do limited car and motorcycle maintenance & minor repairs); the symptoms of hesitation seems to be heat soak related; and thus may be electrical/electronic related. But the full tank refill consistently produces the problems so this points to a fuel or maybe fuel delivery problem. With regards to the stalling while deceleration from highway speed???? I have no idea... the idle controller should have fixed it. The car is up for its 105 kmi major service i.e. timing belt, pulleys, water pumps, etc... Would any of these maintenance help??? I'm open to all ideas. I really like this car a lot. In fact I plan to replace the strut/shocks with Bilsteins, maybe a performance cat back exhaust, and definitely getting rid of the crappy MXMv michellins with the previous Exaltos. But for the past 6 mos, I've been driving my Miata more and more. I'm also hesitant to let my wife drive the GT especially if it may stall at highway speed. Link to comment Share on other sites More sharing options...
GVSUBeef Posted April 6, 2013 Share Posted April 6, 2013 I am by no means an expert, but I notice that you didn't mention anything about cleaning the fuel injectors. I don't mean a fuel additive, but a real in-shop cleaning. If you did get some bad gas and some contaminants got past the filter, they would have plugged up the injectors some. Higher fuel inputs would probably keep enough fuel feeding the engine for it to not sputter and die, but in lower speed, less fuel, more of a chance of misfiring and stalling. Also, I know it's a longshot, but when was the last time the airfilter was replaced? Too little airflow could cause it to compensate with less fuel. Like I said, I don't know much, just trying to be helpful. Link to comment Share on other sites More sharing options...
CDKJudoka Posted April 7, 2013 Share Posted April 7, 2013 Another thing to look at would the the fuel pump itself. They are pretty stout, but if you filled up with bad gas, it could be clogging the strainer on the pump itself. Another thing, and it's a long shot because your car would really run like crap, but maybe your timing belt jumped a tooth. It is due for a new TB anyway, so those could be things to look into. 2014 Legacy 2.5i 6M - FB25 w/ a 6 speed 2002 Impreza 2.5TS - EJ251 w/ a 5 speed (The Stormtrooper) Link to comment Share on other sites More sharing options...
beeemveek1 Posted April 7, 2013 Author Share Posted April 7, 2013 thank you both for the replies. I did change out the air filter. I also asked the tech regarding a possible fuel pump failure or issues. He felt that if the pump was failing then the symptoms would be consistent and not related to heat soak or refilling. Is there a diagnostic test for fuel pump function? I have thought about a failing or partially clogged injector(s). Is there a special cleaning procedure or does it need replacement. With regards to the possibility of a timing belt off a "tooth" wouldn't that cause consistent misfire throughout the rpm? At any rate, the timing belt will need replacement anyway. Thanks again for your suggestions. Link to comment Share on other sites More sharing options...
GVSUBeef Posted April 7, 2013 Share Posted April 7, 2013 In regards to the injectors, there are machines made called Motorvac's that are designed to clean the fuel delivery system. Some people swear by them, some people call them a total scam. They push detergents through the fuel system to clean off carbon deposits. Would probably be about $100. I have never had an issue where this needed to be done, so I can't say if it would help in your situation. You could try picking up a fuel system cleaning additive (again, which one I don't know) and running a tank through with that. That's more likely $10-15. If it helps, great. If it doesn't, you're only out $10. Most likely this wouldn't solve the issue if it exists, but could improve it. If the injectors are the problem, replacing them would be the most effective solution, but at $60 a piece for remanufactured, or $100 a piece for new, plus labor = ouch. If it were me, I'd probably try to the fuel additive first and see if it helped. If it did help, I'd probably try another bottle in another full-tank (or whatever the manufacturer recommends) and see if that would do it. If it didn't fix it completely, I would then try the Motorvac. If there's no change whatsoever after a bottle of the stuff, I'd be off of the fuel injector idea. The thing is, I'm cheap. And if I spent $30 (two bottles) to fix it I'd be happy with that. However, if it is dirty injectors, just spending the $100 to fix it off the bat, might be a better choice as I could be in for $130 after all is said and done. I wish you the best, and I hope I'm leading you on a good path. If not, I apologize. It would be nice if you could find out what your fuel pressure was at the fuel rail and see if it's in spec. That would help you figure out where to start. Bad at the rail would mean not fuel injectors and could point to a weak pump or the clogged screen that CDK is pointing to. Good luck! Link to comment Share on other sites More sharing options...
beeemveek1 Posted April 9, 2013 Author Share Posted April 9, 2013 Thanks for the info regarding the injectors. I typically run Chevron gas in all my vehicles. I'll run a bottle before the next oil change. Updates: Just out of frustration; I went ahead and replace air filter an plugs. The air filter was fine. I could had reused it. The plug electrodes were fine; not too lean or rich. Nice dark tan color.......BUT there's motor oil at the top of the spark cap suction where the rubber covers the valve cover for all 4 cylinders. HOWEVER, cylinder #4 had oil at the base of the spark plug. So looks she gonna need head gaskets. Mind you, the car does not seem to burn any oil or leak any oil. Could my intermittent misfire at partial throttle and intermittent stalling symptoms be caused by a slow leaking head gasket???? Btw, what's a typical cost for replacing head gaskets. I'll add this to timing belt service. Link to comment Share on other sites More sharing options...
GVSUBeef Posted April 10, 2013 Share Posted April 10, 2013 Could be a spark plug tube seal. (Once again...no expert.) I don't know for certain if a head gasket could be causing it...but mine has been slowly leaking oil for two years and I haven't had anything like this happen. As far as cost for a head gasket replacement it isn't good. The estimates that I got were $1200 (friend of a friend) - $1800 (dealer). All included machining the heads, all seals, timing belt and all timing belt replacement components. Link to comment Share on other sites More sharing options...
TurboLag23 Posted April 10, 2013 Share Posted April 10, 2013 Thanks for the info regarding the injectors. I typically run Chevron gas in all my vehicles. I'll run a bottle before the next oil change. Updates: Just out of frustration; I went ahead and replace air filter an plugs. The air filter was fine. I could had reused it. The plug electrodes were fine; not too lean or rich. Nice dark tan color.......BUT there's motor oil at the top of the spark cap suction where the rubber covers the valve cover for all 4 cylinders. HOWEVER, cylinder #4 had oil at the base of the spark plug. So looks she gonna need head gaskets. Mind you, the car does not seem to burn any oil or leak any oil. Could my intermittent misfire at partial throttle and intermittent stalling symptoms be caused by a slow leaking head gasket???? Btw, what's a typical cost for replacing head gaskets. I'll add this to timing belt service. Damn... If your head gasket's going, then yeah get it taken care of with the timing belt change. EJ251's are notorious for head gasket issues. As someone else mentioned, ask about getting the fuel system cleaned/inspected too while they're in there. Other than that, idk what else there is to do. Good luck man. Link to comment Share on other sites More sharing options...
beeemveek1 Posted April 20, 2013 Author Share Posted April 20, 2013 I am by no means a mechanic so after some reading/research... technically, my GT's HG is probably still good. there has been no external leak, no coolant consumption and no oil consumption. So likely just the plug o-gaskets needs replacing. I'll have it replace at the same time when the timing belt, pump, pulley, valve adjust get done. Tell me what you all think out this http://www.subaruforester.org/vbulletin/f89/neutral-switch-78655/ Basically, the symptoms I seem to be having (stumbling/ misfire/ stalling with light throttle and stalling upon deceleration triggering the P0519 code) may be a NEUTRAL SWITCH related. How common is this problem. Anyone else with a N/A 2.5 experienced similar symptoms? Link to comment Share on other sites More sharing options...
Mothali Posted April 20, 2013 Share Posted April 20, 2013 Its likely an air intake sensor, idle air or MAF sensor. Check for vaccum leaks. Link to comment Share on other sites More sharing options...
MicahMonster Posted April 30, 2018 Share Posted April 30, 2018 This is an ancient post, but I have this EXACT problem and was wondering if anyone figured it out. Link to comment Share on other sites More sharing options...
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