bdcvg Posted March 6, 2017 Share Posted March 6, 2017 I,ve read a few threads on misfires and I'm confused on the CEL. I just did timing belts etc. on My OBXT. While the car was down I checked the banjo screens. On the '08 one is under the intake tube. I now have a slightly rough idle and a slight stutter during acceleration. Will a misfire always generate a CEL? I gotta think I dislodged a vacuum line somewhere and it is causing this wierd idle. Link to comment Share on other sites More sharing options...
MilesA Posted March 6, 2017 Share Posted March 6, 2017 As I understand it, the ECU determines misfire by observing minute variations in the crankshaft speed. So, your engine can run rough due to a vacuum leak and not always cause a CEL. Since you were just working around the vacuum lines, your suspicions are probably right. Link to comment Share on other sites More sharing options...
FJuan Posted March 6, 2017 Share Posted March 6, 2017 vacuum hose It only takes 1 damn hose to mess everything up. My wife's balls are delicious. Link to comment Share on other sites More sharing options...
bdcvg Posted March 6, 2017 Author Share Posted March 6, 2017 O.K. That's what I thought. Link to comment Share on other sites More sharing options...
bdcvg Posted March 7, 2017 Author Share Posted March 7, 2017 Hopefully I didn't bend any valves when I did the timing belt. It ran good today just a hint of wierd idle and stutter. Link to comment Share on other sites More sharing options...
xt2005bonbon Posted March 7, 2017 Share Posted March 7, 2017 OP, if you have an android device you should then invest in getting the btssm app for your car. You will be able to view certain live parameters related to boost/vacuum leaks. Furthermore, you will be able to log a parameter called 'roughness count' or 'misfire' for each cylinder. Using this parameter, I was able to diagnose issues in a given cylinder for my cars (cylinder #2). I was getting specific counts of misfires in that cylinder during warm idle due to tight exhaust valve clearance. fyi, this count ranges from 0 to 99. The misfire cel usually gets triggered when this count reaches 30+. Link to comment Share on other sites More sharing options...
xt2005bonbon Posted March 7, 2017 Share Posted March 7, 2017 Also, I am pretty sure if you bent your valves, the engine would barely run! Link to comment Share on other sites More sharing options...
bdcvg Posted March 7, 2017 Author Share Posted March 7, 2017 I'll look for the app, I have Link but haven't played with it much yet. Maybe it has a vacuum reading. Link to comment Share on other sites More sharing options...
bdcvg Posted March 7, 2017 Author Share Posted March 7, 2017 Also, I am pretty sure if you bent your valves, the engine would barely run! Yeah I kinda figured that. When I took the old timing belt off the one cam gear rotated pretty firmly about a quarter of a turn and scared the crap out of Me. Link to comment Share on other sites More sharing options...
xt2005bonbon Posted March 7, 2017 Share Posted March 7, 2017 Yeah. The cams on the driver side are under load for timing belt removal. So you do have to be careful. But I think you should still be fine. The btssm app has been designed by one of our forum members. So this is an app specifically tailored to our car and can read parameters which most generic apps won't be able to (like feedback knock, misfires, etc..). Go to this thread for more details. The developer (heiche) is an awesome guy. http://legacygt.com/forums/showthread.php/btssm-bluetooth-adapter-app-229709.html Link to comment Share on other sites More sharing options...
FJuan Posted March 7, 2017 Share Posted March 7, 2017 If he discontinued the battery that will reset the ECU, with will cause the motor to run rough for a while. The ECU is relearning the air/fuel ratios. My wife's balls are delicious. Link to comment Share on other sites More sharing options...
bdcvg Posted March 7, 2017 Author Share Posted March 7, 2017 If he discontinued the battery that will reset the ECU, with will cause the motor to run rough for a while. The ECU is relearning the air/fuel ratios. I thought about this too, I switched to a Lightweight pulleyat the same time I drove the car about 60 hiway miles, maybe not enough yet? Link to comment Share on other sites More sharing options...
xt2005bonbon Posted March 7, 2017 Share Posted March 7, 2017 If he discontinued the battery that will reset the ECU, with will cause the motor to run rough for a while. The ECU is relearning the air/fuel ratios. For some reasons, my 05 does not have this issue . But the 06 does. Link to comment Share on other sites More sharing options...
bdcvg Posted March 13, 2017 Author Share Posted March 13, 2017 How long should it take for the ecu to reset? Link to comment Share on other sites More sharing options...
bdcvg Posted March 13, 2017 Author Share Posted March 13, 2017 I mean re-learn. I still have a slight bounce / shake at idle but the rpm is 740-750. Link to comment Share on other sites More sharing options...
FJuan Posted March 13, 2017 Share Posted March 13, 2017 Just takes a few mins if you disconnect the battery to reset the ECU. It usually takes about 20 mins +/- of constant driving for the ECU to relearn. My wife's balls are delicious. Link to comment Share on other sites More sharing options...
xt2005bonbon Posted March 13, 2017 Share Posted March 13, 2017 It learns really quickly from my experience (like within the first couple of miles). Essentially, 2 or 3 minutes after the car has been started and left idling (after a ECU reset), I noticed the ECU was already beginning to apply fuel correction and 'learning' them. So it is usually quick. Link to comment Share on other sites More sharing options...
Perscitus Posted March 13, 2017 Share Posted March 13, 2017 Learning starts as soon as the car re-enters CL for the first time after an ECU/TCU reset (either hard or soft). This means that the first thing to start setting are the low range Fuel trims (A, B), then as you drive the car learns C,D, E (if applicable) and as it exits pure FKC, enter and exits RC and enters FLKC - Timing adjustments also start to fill in across the LV RPM/Load map. Of course the whole process is continuous and just keep going after a reset, but how fast it fills in most of the data points and settles on some values is usually a function of: a. compensations (coolant temp up to temp, ATF/CVTF up to temp, intake temps) b. driving style (how many points of the Fuel and Timing Learn we hit and how often) c. CL/OL tune config (when CL kicks in and how often) I would say you typically want to only 'trust' LVs after about an hour or two of continuous mixed mode driving at operating temp after a reset. Better yet, give the car a day or a week of driving even to see some meaningful LV data. In between, the only thing that will tell you how the tune is doing and how well scaling, calibrations, etc are set are logs. Link to comment Share on other sites More sharing options...
bdcvg Posted March 13, 2017 Author Share Posted March 13, 2017 Well maybe the car is just not that smooth at idle, My '05 N/A Impreza doesn't seem that way. Link to comment Share on other sites More sharing options...
xt2005bonbon Posted March 13, 2017 Share Posted March 13, 2017 My 05 was not smooth at idle. Turned out an exhaust valve did not have any clearance. Since I put the clearance back to spec on that car, the idle is perfect. Can't remember if I asked before, can you log misfires and your fuel trims? Link to comment Share on other sites More sharing options...
bdcvg Posted March 13, 2017 Author Share Posted March 13, 2017 I have an OBD reader linked to My phone , still figuring out how it works. The car has 82K on it and I just replaced timing belts , and spark plugs. Maybe I didn't get a plug boot on right. I am not getting a CEL. I couldn't find any vacuum leaks after spraying quite a bit of carb cleaner around where I was working Link to comment Share on other sites More sharing options...
bdcvg Posted March 15, 2017 Author Share Posted March 15, 2017 O.K. I got the BTsSM app working and it shows a missfire #4 . It didn't miss before I did the timing belt kit and new spark plugs. So I'll make sure the connection at the plug is good and the cable is good on the coil pack. Link to comment Share on other sites More sharing options...
xt2005bonbon Posted March 15, 2017 Share Posted March 15, 2017 oh you got it? Good on you. Do you actually have a cel or it just shows counts of misfire? Also, when does the misfire count show up? warm or cold engine? at idle or any rpm range? can you post an lv as well so we can see your fuel trims? Link to comment Share on other sites More sharing options...
bdcvg Posted March 15, 2017 Author Share Posted March 15, 2017 No I do not have a cel. I just connected to a cold engine to get the app to work at idle speed. I am using a Scantool OBDLX reader and I haven't figured out how to post anything yet. Link to comment Share on other sites More sharing options...
xt2005bonbon Posted March 15, 2017 Share Posted March 15, 2017 No I do not have a cel. I just connected to a cold engine to get the app to work at idle speed. I am using a Scantool OBDLX reader and I haven't figured out how to post anything yet. ok. How many counts are you getting? Does the misfire go away when fully warmed at idle? There is a button called 'LV' on the btssm app where it will retrieve a 'learning view'. It is automatically saved in your phone/tablet. You just need to upload that small file here. Link to comment Share on other sites More sharing options...
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