zedhex Posted July 27, 2014 Share Posted July 27, 2014 Hi All, I have a problem with hot starts on my car (Soarer, but don't let that put you off). The full spec is: 1JZGTE engine HKS 30307S turbo 550 USDM injectors Superspark coilpacks Emanage Ultimate The car is starting fine when cold. It runs well, idles properly and has plenty of power. If I shut off for a few seconds it just won't re-start - bar the occasional cylinder firing without catching (lots of fun at petrol stations). If I wait for about 15 mins, it starts right up. I have set the injectors up correctly in the EMU (370 before, 530 after) and the lag is set to 0.8ms (after setting it by disconnecting the lambda sensor and adjusting to give a 12:0 AFR idle). I have checked the crank angle sensor, cam sensor, temp sensor, IAC valve, vsv valve, manifold air leaks etc. etc. I have tried adding/removing fuel from the injector map, adding/removing fuel from the air flow map. Nothing works. Does anyone have any ideas? Quote Link to comment Share on other sites More sharing options...
Wez Posted July 27, 2014 Share Posted July 27, 2014 12AFR idle? Should be down in the 14 to 15 for idle Quote Link to comment Share on other sites More sharing options...
chrispot Posted July 27, 2014 Share Posted July 27, 2014 (edited) do you have an after market fuel pressure regulator fitted? when i had my old mk3 supra it had the same problem with hot starts with a crap aftermarket fpr, what happens is the regulator leaks fuel back to the tank and loses fuel pressure at the injectors, and with a hot engine boils/vapourises the fuel give you an air lock so to speak. the mk4 supra has a vsv to raise the fuel pressure when hot to help with hot starts. my mk3 supra had this fuel increase when hot system but the owner before me removed it. when i change back to an original fpr all was good again even without the fuel pressure increase when hot system. it could be your original fpr faulty (toyota one) not necessarily an aftermarket one? might not be this at all, when you do sort it could you please post the answer. regards chris Edited July 27, 2014 by chrispot added a bit (see edit history) Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted July 27, 2014 Share Posted July 27, 2014 Symptoms are those of leaking injectors over fuelling on hot starts. I can flow and leak test them if you wish to pursue this possibility. Quote Link to comment Share on other sites More sharing options...
zedhex Posted July 27, 2014 Author Share Posted July 27, 2014 (edited) Hi Chris: The injectors have already been cleaned and flow tested, and fuel pressure is steady at 43psi, and only slowly drops after shut-off. If it was a leaky injector, I would lose fuel pressure much quicker. I don't think it's running rich on hot start - if anything, it feels like its lean. When it does eventually start, it always runs leans for a few seconds before getting back to stoich. Edited July 27, 2014 by zedhex (see edit history) Quote Link to comment Share on other sites More sharing options...
zedhex Posted July 27, 2014 Author Share Posted July 27, 2014 (edited) Wez: it is at 14.5 at idle. I was referring to the technique for setting the correct lag time - you disconnect the lambda sensor, set the afr to 12 - 12.5 at idle using the lag setting only. You then re-connect the lambda and allow the ecu to bring it up to stoich in closed loop. Relying on tables from websites just isn't reliable for setting injector lag. Edited July 27, 2014 by zedhex (see edit history) Quote Link to comment Share on other sites More sharing options...
Pig Posted July 27, 2014 Share Posted July 27, 2014 Have a look through this thread as Ian had similar issues. http://www.mkivsupra.net/vbb/showthread.php?293457-Warm-start-problem-ongoing-investigation Quote Link to comment Share on other sites More sharing options...
zedhex Posted July 28, 2014 Author Share Posted July 28, 2014 (edited) Cheers Pig - this looks very, very promising: http://www.mkivsupra.net/vbb/showthread.php?293457-Warm-start-problem-ongoing-investigation&p=3890904&viewfull=1#post3890904 Is Ian C still around? I need to know how he created a 'load site' on the emu for 500 and 600rpm UPDATE: I added 20% to the airflow map at atmo pressure/500rpm, and it started right up - and that was after a full power run, hotter than hell. It still ran like poo for the first 20 secs or so, but its a lot better than nothing. With a bit more tweaking I should be able to sort it (now that I am going in the right direction). Thanks guys - this forum is the best. Edited July 28, 2014 by zedhex (see edit history) Quote Link to comment Share on other sites More sharing options...
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