Car starts badly when warm

[darkb16a1]

Guys, I came to a strange issue. B16 engine, JRSC compressor and 450cc DSM injectors. Once the bigger injectors were put and the JRSC took place, I'm having issues with starting the engine when warm. AFR on idle is fine, multiplier was recalculated using \"new injectors size\" value in Ectune. When I stop my car and immediately (up to 1 minute) start, no problem at all. If the car is stopped for more than 3 minutes, it won't start easily, I have to wait up to 5 seconds holding the starter until it catches, sometimes I even have to slightly hit the throttle. I tried to play with the \"crank fuel table\", the \"post start fuel table\", even modified the values where I see ECU reads values in the fuel table. Funny thing is that no matter what I do (extreme lean, slightly leaner, more fuel..) the situation basically doesn't change. Any ideas what else to try ? My LC-1 wideband unfortunately shows \"heating up\" during cranking so not quite sure what AFR I have at the exact moment of cranking.

[TopMountGSR]

Modify your crank fuel map, Last three columns 177 ECT = 800 192 ECT = 750 286 ECT = 500 I used to get stranded on hot restarts [wouldnt start back up] for sometimes up to an hour. This fixed it. Then goto your IAT corrections Add fuel smoothly past your normal operating conditions but only in the idle/light load row. I normally step the fuel in pretty aggressive in those areas, top right box could have a '12' fuel value in it. Defaults subtract fuel there, but its always one of the first things I change. You can maintain a desired air fuel while heat soaking better and for longer. Last trick, turn your idle settings up a bit, target idle, rolling idle, stopped idle and duty cycle. Also, obviously lean can cause hard starts, but so can an overly rich symptom normally found in the ECT tables, they are way to rich by default, good starting point is to cut them in half. These tricks should solve your issues if your fuel maps are semi correct.

[darkb16a1]

Topmount, thanx for the response, unfortunately this did not seem to work. I tried to follow your steps, also tried them the other way round in terms of decreasing values, but the engine behaves very similarly. Moreover, when I made the suggested changes to increase fuel values, even starting after just a few seconds of engine not running was a problem, so it actually made things worse. So I reverted the changes and still am having issues when trying to start warm engine after about 3-5 minutes of not running.

[Bindegal]

To help diagnose, try powering your wideband from a seperate power source so it will work continuously during cranking tests. Log directly from the wideband unit itself to see actual AFR´s. Of course AFR will read as lean/open-air until the mixture fires. But when it does fire you might have a better chance to see if it´s lean or rich. Keeping in mind that an overly rich mixture might read as lean... argh tough things to diagnose If the start sounds rich when it finally does fire up, it might be the injectors leaking. I have seen this sometimes even on stock injectors from old Honda´s. Yup, and all 4 of them. If you have access to a fuel pressure gauge, check if fuel pressure stays up after you turn off the engine. I find that DSM injectors up to 550cc are usually very easy to work with, when in working order of course. /Allan