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Thread: First problem in 3 years....

  1. #1
    Harley818's Avatar
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    First problem in 3 years....

    Hi guys,
    Been driving this car for 3 summers now, but recently have been having a few issues.
    Wondering if you guys have any experience with these symptoms.

    Recently I have been having backfires when I let off the throttle, but power was still great.
    In the last week, backfires have been getting worse.
    Sometime in the last 2 months it developed a ticking sound at idle, but its getting louder. Sounds like a sticking valve, but I had the valves professionally done when I put the engine together.
    Yesterday it ran really rough, it bogged badly when I stepped on the throttle . Power was way lower than normal so I drove it gently home.

    At some time the engine check light came on.
    By coincidence..... my speedometer started randomly fluctuating
    When I checked the engine code with my ODB computer, I got P0500 - Vehicle speed Sensor A. Not sure what this means.

    I am working my way through the engine and ECM, making sure all the connectors are secure and checking all my grounds first.
    Then I am thinking it may be injector related. I'll pull each one out and see if it makes any difference.
    Then I'll check the coils.

    Not sure where to go after that.

    Anyone got any ideas.... that would be helpful.
    Harley
    Bought 2002 Donor Jan 2014
    First Start Jan 18, 2015
    First Drive Feb 14, 2015

  2. #2
    Senior Member STiPWRD's Avatar
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    It may be an electrical issue that's causing the ECU to pull timing or possibly a bad ground? It sounds like you're checking in the right places. I would continue looking at what the ECU is reading and data logging to help troubleshoot the issue. You could also check the spark plugs and fuel filter. Also, I'm not sure if you're running on the stock tune or if the car was tuned at some point. A quick compression test may also be worth a shot if you suspect a bad valve. I'm not familiar with the P0500 code but I would research that. Hope that helps.

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    Harley818's Avatar
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    OK, thanks for the quick response.
    Harley
    Bought 2002 Donor Jan 2014
    First Start Jan 18, 2015
    First Drive Feb 14, 2015

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    It is possible an exhaust manifold/header leak can cause the symptoms you describe. Ticking at idle when exhaust gas escapes and the popping or backfire when air mixes with unburned fuel on deceleration. It is worth investigating.

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    Senior Member Bob_n_Cincy's Avatar
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    Harley, what is you definition of backfire. A gunshot out the tailpipe? A cough back through the intake?

    Some of your symptoms could be related to running to lean. I would check your fuel pressure.
    Bob
    818S #22 Candy Blue Frame, Front Gas Tank, 2.5L Turbo, Rear radiator, Shortened Transmission, Wookiee Compatible, Console mounted MR2 Shifter, Custom ECU panel, AWIC soon
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    Quote Originally Posted by RDRP View Post
    It is possible an exhaust manifold/header leak can cause the symptoms you describe. Ticking at idle when exhaust gas escapes and the popping or backfire when air mixes with unburned fuel on deceleration. It is worth investigating.
    Thanks RDRP..... I did check the exhaust connections and they are good. Definitely a mechanical sounding item. I've been using a tube to try to locate the sound, but its difficult to pinpoint.
    Harley
    Bought 2002 Donor Jan 2014
    First Start Jan 18, 2015
    First Drive Feb 14, 2015

  10. #7
    Harley818's Avatar
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    Quote Originally Posted by Bob_n_Cincy View Post
    Harley, what is you definition of backfire. A gunshot out the tailpipe? A cough back through the intake?

    Some of your symptoms could be related to running to lean. I would check your fuel pressure.
    Bob
    It sounds like a cough through the intercooler. Fuel pressure is good. I have a gauge on my dash.
    Im going to try some datalogging with my Accessport V3. I have to figure out how to do that......
    I tried disconnecting each injector last night. Not much difference while idling, but when I moved it up to around 1200 - 1500 rpm there was a noticable difference for each injector so I guess they are working. Not sure if they are metering correct AF though.
    I had it tuned a couple years ago and was running great till last week.

    Is it possible that the VSS is causing it to go into limp mode? I was reading something about that online last night. Did 2002 have ECM with limp mode?
    Harley
    Bought 2002 Donor Jan 2014
    First Start Jan 18, 2015
    First Drive Feb 14, 2015

  11. #8
    Senior Member Bob_n_Cincy's Avatar
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    Quote Originally Posted by Harley818 View Post
    It sounds like a cough through the intercooler. Fuel pressure is good. I have a gauge on my dash.
    Im going to try some datalogging with my Accessport V3. I have to figure out how to do that......
    I tried disconnecting each injector last night. Not much difference while idling, but when I moved it up to around 1200 - 1500 rpm there was a noticable difference for each injector so I guess they are working. Not sure if they are metering correct AF though.
    I had it tuned a couple years ago and was running great till last week.

    Is it possible that the VSS is causing it to go into limp mode? I was reading something about that online last night. Did 2002 have ECM with limp mode?
    With our 04 FXT ecu, we had some VSS problems and fault code. It cause maybe a 20 to 30% drop in power, but drivability was fine. When it happened Michael finished his track session.
    818S #22 Candy Blue Frame, Front Gas Tank, 2.5L Turbo, Rear radiator, Shortened Transmission, Wookiee Compatible, Console mounted MR2 Shifter, Custom ECU panel, AWIC soon
    My Son Michael's Turbo ICE Build X22 http://thefactoryfiveforum.com/showt...rts-818S-Build
    My Electric Supercar Build X21 (on hold until winter) http://thefactoryfiveforum.com/showt...e-Build-Thread

  12. #9
    Harley818's Avatar
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    Quote Originally Posted by Bob_n_Cincy View Post
    With our 04 FXT ecu, we had some VSS problems and fault code. It cause maybe a 20 to 30% drop in power, but drivability was fine. When it happened Michael finished his track session.
    I'm replacing the VSS, then I'll see what I have ......
    I guess it hasn't been out since 2002. The 17mm just rounded out the flats so I had to break it apart and chisel it out to get it out...
    Harley
    Bought 2002 Donor Jan 2014
    First Start Jan 18, 2015
    First Drive Feb 14, 2015

  13. #10
    Senior Member Bob_n_Cincy's Avatar
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    Quote Originally Posted by Harley818 View Post
    I'm replacing the VSS, then I'll see what I have ......
    I guess it hasn't been out since 2002. The 17mm just rounded out the flats so I had to break it apart and chisel it out to get it out...
    When I blew our transmission. I found a 2012 5mt to replace it. The 2012 doesn't have a vss in the transmission. So I added a sensor to the front wheel. Still working great.
    P1050847s.jpg

    Keep us informed on your results.
    Bob
    818S #22 Candy Blue Frame, Front Gas Tank, 2.5L Turbo, Rear radiator, Shortened Transmission, Wookiee Compatible, Console mounted MR2 Shifter, Custom ECU panel, AWIC soon
    My Son Michael's Turbo ICE Build X22 http://thefactoryfiveforum.com/showt...rts-818S-Build
    My Electric Supercar Build X21 (on hold until winter) http://thefactoryfiveforum.com/showt...e-Build-Thread

  14. #11
    Harley818's Avatar
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    Hi Guys..... wondering if any of you Subaru guys can help with a couple items.

    So I replaced the VSS and now have functioning speedo and no longer in limp mode.
    I have most of the power back… but not all. And the car seems to be running hotter temps.
    The ticking sound is still there – noticeable at idle and just off idle.

    Also, something strange with my radiator fans.
    The fans normally don’t come on until the coolant reaches 205 degrees, when they both come on.
    This cools the engine down to about 180 when they turn off, and the cycle repeats if it gets back to 205 (usually in stop and go traffic).
    However, whats happening now is the fans turn on immediately when I start the car. They run continuously I think…. Haven’t done extensive tests.
    I also notice that the engine seems to be running hotter for some reason. Its fine when moving, but gets hotter faster when in traffic.

    I noticed my battery is low…probably from not driving the car regularly, so I am charging it with my battery tender.
    Could low battery cause the control system to act differently with the fans?
    What would cause the fans to go on immediately?

    Regarding the higher temps….. could the ticking be injectors that aren’t working correctly? I have some new STI pinks that I am going to install and have re-tuned. They are new and have 565cc flow instead of 420cc flow. Maybe the old injectors with 100K miles aren’t working correctly… thus the ticking? And running lean… hotter temps?

    Any comments would be helpful.
    Harley
    Bought 2002 Donor Jan 2014
    First Start Jan 18, 2015
    First Drive Feb 14, 2015

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    Senior Member STiPWRD's Avatar
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    You may want to check that your engine coolant temp sensor and fan relays are working properly. If either is malfunctioning, I can see how that would turn on both fans. Any check engine codes?

    From the FSM:
    Untitled.jpg

    I don't remember for sure but I think both fans may also come on if the ECU thinks it's in reflash mode.

  16. #13
    Harley818's Avatar
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    Quote Originally Posted by STiPWRD View Post
    You may want to check that your engine coolant temp sensor and fan relays are working properly. If either is malfunctioning, I can see how that would turn on both fans. Any check engine codes?

    From the FSM:
    Untitled.jpg

    I don't remember for sure but I think both fans may also come on if the ECU thinks it's in reflash mode.
    Thanks for the chart..... I don't have AC, I deleted it.
    I'm thinking now that I did have an error code related to the VSS sensor failure - which I deleted with the ODBII diagnostic device I have. Could that have put it into reflash mode?
    I'll hook up my Accessport - hopefully it tells me if its in reflash mode.
    Harley
    Bought 2002 Donor Jan 2014
    First Start Jan 18, 2015
    First Drive Feb 14, 2015

  17. #14
    Senior Member STiPWRD's Avatar
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    I would definitely chase down any lingering check engine codes. Make sure the coolant sensor is actually reading the right value. You may already have the FSM but here is the fan circuit:
    fans.jpg

    If the ECU is sending power to the fan relays (probably 5V), then there is some condition that's causing the issue internally. If there is no power going to the relay and the fans are still running, then the relay is probably the issue.

    Another option is to install those new injectors and see if the tuner can figure out the fan problem.

  18. #15
    Harley818's Avatar
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    Quote Originally Posted by STiPWRD View Post
    I would definitely chase down any lingering check engine codes. Make sure the coolant sensor is actually reading the right value. You may already have the FSM but here is the fan circuit:
    fans.jpg

    If the ECU is sending power to the fan relays (probably 5V), then there is some condition that's causing the issue internally. If there is no power going to the relay and the fans are still running, then the relay is probably the issue.

    Another option is to install those new injectors and see if the tuner can figure out the fan problem.
    Funny you should say that..... I was thinking the same thing about the tuner.

    thanks for the help.
    Harley
    Bought 2002 Donor Jan 2014
    First Start Jan 18, 2015
    First Drive Feb 14, 2015

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    Harley here’s a link to my grounding issue a while back still running strong today
    https://thefactoryfiveforum.com/show...ght=Flickering

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  21. #17
    Harley818's Avatar
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    Quote Originally Posted by DMC7492 View Post
    Harley here’s a link to my grounding issue a while back still running strong today
    https://thefactoryfiveforum.com/show...ght=Flickering

    Thanks,
    I checked the intake and engine grounds, as well as ECM grounds, but I'll check the others you mentioned.
    Harley
    Bought 2002 Donor Jan 2014
    First Start Jan 18, 2015
    First Drive Feb 14, 2015

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    Harley818's Avatar
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    I rechecked and retightened all the grounds. Voltmeter showed 13.3 V at all points on the engine, trans, and ECU and other grounds.
    Fans now running correctly but I still have the ticking in the engine which is getting a bit worse.
    Sometimes its soft, other times its quite loud like a sticking valve.
    Idles OK, but hesitates and coughs when you dip in to the throttle and backfires when you let up quickly. Still not pulling as strong as before either.

    Took the car to the tuner planning to replace the injectors and get his opinion. He didn't like the ticking even though it was not loud at the time.
    We pulled the oil filter and cut it apart. A couple small aluminum flakes but not much more.

    After changing the oil, we restarted and let it run for 5 mins. Ticking got quite loud, and he noticed a misfire at some times. Definitely still some hesitation off idle.
    He did some data logging and said everything seems normal. A/F ratio was good, no knocking, oil pressure etc. all good.
    With the noise, he advised to pull the engine and see what it is before it gets worse.

    I guess I have some work ahead of me.
    Once I pull it and open it up, if I see any issues at all, I'm thinking of just getting an OEM shortblock. I'm not going for crazy power and plan to keep it around 300 - 320 Hp.
    I'm at 265 now, but might add a bigger turbo to get to 300.
    Flatirons has some built by subaru for a reasonable price. anyone have any positive or negative comments on these guys.... in Boulder, CO?
    Harley
    Bought 2002 Donor Jan 2014
    First Start Jan 18, 2015
    First Drive Feb 14, 2015

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    Just a wild shot - is it possible you are hearing injector "bang" in the fuel lines. Subaru and others put those pulse dampers here and there in the lines to kill that noise which can get pretty loud from what I've read.
    Art Quillen

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    Senior Member STiPWRD's Avatar
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    Before pulling the engine, I would remove the valve covers and check the valve clearances. Sometimes the cam followers (buckets) get worn down. I'd also do a quick compression test while the starter can crank over the motor to verify your valves are seating properly.

    As far as the misfires, I'd check the spark plugs. You could try replacing the injectors and seeing if that makes a difference.

    I'd also recommend inspecting the oil in the pan. If you don't see any signs of wear and you're considering replacing the block anyway then there isn't much risk in running the current block.

  25. #21
    Senior Member AZPete's Avatar
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    I've bought from Flatiron in Boulder and they had good prices, shipped quickly and accurately.
    818S/C : Chassis #25 with 06 WRX 2.5 turbo, ABS, cruise, PS, A/C, Apple CarPlay, rear camera, power windows & locks, leather & other complexities.
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  26. #22
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    Quote Originally Posted by aquillen View Post
    Just a wild shot - is it possible you are hearing injector "bang" in the fuel lines. Subaru and others put those pulse dampers here and there in the lines to kill that noise which can get pretty loud from what I've read.
    Thanks Art. I will check that out.
    I don't really want to pull the engine.
    Harley
    Bought 2002 Donor Jan 2014
    First Start Jan 18, 2015
    First Drive Feb 14, 2015

  27. #23
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    Quote Originally Posted by STiPWRD View Post
    Before pulling the engine, I would remove the valve covers and check the valve clearances. Sometimes the cam followers (buckets) get worn down. I'd also do a quick compression test while the starter can crank over the motor to verify your valves are seating properly.

    As far as the misfires, I'd check the spark plugs. You could try replacing the injectors and seeing if that makes a difference.

    I'd also recommend inspecting the oil in the pan. If you don't see any signs of wear and you're considering replacing the block anyway then there isn't much risk in running the current block.
    Thanks StipWRD - Oil in the pan when we drained it looked dark but no metal flakes and no metal powder.... tuner said the noise wasn't injectors (I was hoping it was and had a set of injectors ready for him to try.)
    Good call to check the plugs, although they only have about 5000km on them.
    Valves were professionally done with a local engine shop who has a good reputation and does a lot of Subaru engines so Im thinking its not that.... and its quite loud at times, subtle other times while idling. Valve noise at idle would be consistent wouldn't they?
    I'll check the plugs.
    Harley
    Bought 2002 Donor Jan 2014
    First Start Jan 18, 2015
    First Drive Feb 14, 2015

  28. #24
    Harley818's Avatar
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    Quote Originally Posted by AZPete View Post
    I've bought from Flatiron in Boulder and they had good prices, shipped quickly and accurately.

    good to know. IN case I need a short block.....

    I talked to them today.

    I'm thinking about a hybrid.... using a 2.5 block with the 2.0 heads and thicker gasket.
    Anyone on this forum have any experience with a hybrid?
    Apparently the heads etc bolt right on, same mounts etc.

    Of course, then that begs the question of a turbo upgrade to a 16G.

    "Never replace parts without upgrading"
    Last edited by Harley818; Today at 12:39 AM.
    Harley
    Bought 2002 Donor Jan 2014
    First Start Jan 18, 2015
    First Drive Feb 14, 2015

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