Ben Jones Posted June 23, 2012 Report Share Posted June 23, 2012 Hey guys, I have an intermittent fault that has stranded me once and scared me a couple other times. Apologies for the long read. Car details; G4 Extreme Red, Subaru EZ30 with AVCS,  factory H6 loom with appropriate shielding and grounding, used as a daily driven road car 99% of the time. Symptoms: First time this occurred, i was coasting into a roundabout on the overrun fuel cut. As i hit the clutch to shift down - the engine stalled without drama, just quietly died. So i coasted to the side of the road and attempted to restart. The car would not fire and i could hear a pop out the exhaust every 5-10revolutions. I connected my laptop and no fault codes were present, trigger error counters were at 1 or 2 and not increasing. After quite a few unsuccessful attempts to start the car, i gave up and went for a walk. 5 mins later when i returned - it fired up and ran perfectly fine. Second time this happened, i was again on the overrun fuel cut coasting down a hill, when i went to get back on the gas - i had no power so kept shifting down gears with my foot partially on the throttle until it started running again. There was no misfiring or afterburning - just smooth deceleration as if someone had cut the ignition completely. When it resumed firing - it did so smoothly and ran flawlessly. This happened a 3rd and 4th time, on all occasions i was able to just keep chopping gears until it ran again. Every time PC link has not shown any fault codes or errors and the tacho/speedo which are ECU driven have continued to work correctly. It has only happened 4 times over 10,000km so i havnt been able to catch it when datalogging. I cant find any problems with the power supply to the injectors or coil packs - they are all run on the same relay as the ECU so surely if it was to quit - the tacho and speedo would also die. It has happened across 2 different firmware version so im reluctant to blame the ECU but dont know where else to look. Ideas? Quote Link to comment Share on other sites More sharing options...
Dtech Motorsport Posted June 24, 2012 Report Share Posted June 24, 2012 HI Ben Firstly what version firmware are you running? If you are not on the lastest version then i would suggest upgrading to the latest V4.9.3 Secondly are you still using the factory main relay ? If so i would suggest replacing that with a new one as well. Hope that helps Regards Dave [email protected] www.dtechmotorsport.com Quote Link to comment Share on other sites More sharing options...
Scott Posted June 26, 2012 Report Share Posted June 26, 2012 Hi Ben, Dave's advice is right on. It sounds like you are losing a power supply to the coils or injectors. Is your ignition system setup coils on plugs with built in igniters? Another possibility could be your fuel pump or fuel pump relay. It can be difficult to track down intermittent problems like this, hopefully the problem will play up for you more often or ideally bring you to a complete stop so testing can be carried out. Regards, Scott Quote Link to comment Share on other sites More sharing options...
Ben Jones Posted June 28, 2012 Author Report Share Posted June 28, 2012 Latest update: It died again this morning on my way to work. I left the car idling outside a shop and when i returned 2 mins later - it had stalled. So i attempted to restart and got the familiar cranking with popping out the exhaust. Giving it more throttle caused the popping to increase in frequency and volume. After cycling the ignition - the 2nd cranking attempt got a couple of cylinders firing but not enough to get it going. I didnt have my laptop on me so couldnt check any of the trigger errors! 3rd attempt i left the ignition off for a couple of minutes and it fired right up and idled perfect. Fuel pump was definately priming during all of this. Its almost as if the timing is out on some cylinders. My second guess would have been lack of fuel but that wouldnt explain the pops/flames out the exhaust. Battery voltage is good and yes all cylinders are coil on plug with built in ignitors. Now running firmware V4.9.3.  Experienced identical problem on V4.9.2. Quote Link to comment Share on other sites More sharing options...
Ben Jones Posted June 28, 2012 Author Report Share Posted June 28, 2012 Also gutted i didnt have a laptop or even a multimeter on me. Any drawbacks to running the built in logging from now on to try and catch this? Quote Link to comment Share on other sites More sharing options...
Scott Posted July 1, 2012 Report Share Posted July 1, 2012 Hi Ben, If you can set the on-board logging up and record while the problem is occurring we can have a look at the log and it will hopefully help us identify what is happening. The on-board logging only logs certain parameters and only has limited space, so it would be best to clear the logs, then record a good start for reference. Then when the fault occurs next, record that and we can compare the two. Cheers, Scott Quote Link to comment Share on other sites More sharing options...
Ben Jones Posted July 12, 2012 Author Report Share Posted July 12, 2012 Yay I have progress! So I was in the shed tonight configuring the Link after putting my wideband LC-1 on the car. It was idling warm when suddenly stopped. Since i had PCLink running anyways - i was able to start logging almost immediately. I started the log and noticed it inserted 15 seconds prior to my starting point (not sure how) and during those 15 seconds showed the engine stalling. Ive had a snoop through and cant find anything of interest. You can clearly see the seperate cranking attempts. I found it interesting that as i disengaged the starter - the engine would cough backwards and spike the rpm reading and bump the trigger error counter. During all cranking attempts there was popping and smoke from the exhaust , no backfiring in the intake and occasionally one or 2 cylinders would pick up as can be seen in the RPM log. I tried about 6 seperate cranks with throttle and without - 3 captured on this log and 3 on another after i'd checked the injectors for power (which was present). As soon as i cycled the ignition - the engine started and ran perfect with all parameters normal. Log file attached. Quote Link to comment Share on other sites More sharing options...
Scott Posted July 13, 2012 Report Share Posted July 13, 2012 Hi Ben, Great to hear you were able to capture a log. On later firmware versions the ECU is continuously logging for the prior 15 seconds for situations just like yours. I will try and have a look at the log later this afternoon or on Monday and see if I can notice anything unusual. Cheers, Scott. Quote Link to comment Share on other sites More sharing options...
Scott Posted July 15, 2012 Report Share Posted July 15, 2012 Hi again Ben, I have had a look at your log, but am unable to notice anything that is causing the problem. In the log the RPM is already falling while the trigger signals are still good. Your injector duty cycle is fine, as is your MAP, Battery voltage, TPS and AFR. When the problem is occuring and you turn your ignition on, can you hear your fuel pump priming? Regards, Scott Quote Link to comment Share on other sites More sharing options...
Ben Jones Posted July 16, 2012 Author Report Share Posted July 16, 2012 Hi Scott, I can hear the pump prime when i cycle the key but cant tell if its running or not with the engine cranking. I hooked up the status wire from the fuel pump controller to one of my digital inputs but havnt had it enabled since i'd forgotten about it until now. I will activate this input and make sure its logged. Im pretty certain its not a fuel pump failure since disabling the pump at idle causes it to run crappy on low pressure for a few seconds before it stalls. I'll keep my laptop/multimeter handy for the next time the fault occurs and will try to get some more answers/data.  Quote Link to comment Share on other sites More sharing options...
Ben Jones Posted September 25, 2012 Author Report Share Posted September 25, 2012 Just to update this thread, took the Legacy around Taupo yesterday and the problem showed up again. Everything had been running fine for about 4,000km on the road and was great throughout the day on the track except for one moment 1 lap in to my 3rd run of the day. The engine suddenly lost all power as before. With no interior and a rice cannon fitted - i could clearly hear what was going on and all cylinders lost power at the same time and immediately. No pops or farts - just like someone had flicked the ignition off. Tacho and speedo were still displaying correctly (link driven) and no CEL. I kept my foot on the gas and rowed down through the gears until i was off the track. Then I came off the gas, hit the clutch and the engine dropped to idle and ran smoothly. Without sticking around to ask questions, i mashed the loud pedal and gave it hell for a few more laps. Enabled on board logging at that point but not a single problem for the rest of the day. I havnt looked too hard at the logs but all the main parameters are being logged correctly. Quote Link to comment Share on other sites More sharing options...
Ben Jones Posted March 14, 2013 Author Report Share Posted March 14, 2013 Another update. Problem is still occurring. Not very often these days but its still an annoyance. Everything i can see tells me that the ECU is losing the right firing order. Cycling the ignition a couple times always fixes the problem. Have had it occur a few times on first start getting back to my car.  You look like a bit of a tit trying to start it up with pops and bangs coming from the exhaust in the middle of town. Given the sparse triggers on the camshaft and the amount of advance possible from the AVCS, is it at all possible the ECU is getting the ignition timing out by 360?  Quote Link to comment Share on other sites More sharing options...
Nate Anderson Posted May 2, 2013 Report Share Posted May 2, 2013 Hi Ben, I sent you a message, similar thing is happening to me. Quote Link to comment Share on other sites More sharing options...
Sameh Yehia Posted October 11, 2014 Report Share Posted October 11, 2014 hey guys,i am having similar issues with 2jz non vvti..have anybody fixed it ? Quote Link to comment Share on other sites More sharing options...
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