Hi im having issue low idle after engine shutdown 15-45min (hot start). If press gas pedal the idle will go back to normal. right now using Hondata S300 engine management. I already try to add more cranking fuel result now the car hard to hot start. Cold start running just fine. Need some advice to trouble shoot the issue. Thanks.

 

Its a fuel injector issue. Old style fuel injectors heat soak and as a result don't inject as much fuel per pulse. The newer Ev14 style injectors dont suffer from this issue as much.

M54 Megasquirt 3: Fuel Injector Heat soak

 

Thanks muckman for the advice

 

Are you running open or closed loop? A friend had issues while trying to run closed loop with an Autometer Wideband O2 sensor (30 second warm up time no matter what). IIRC is was saying it was pig rich which was causing the ECU to pull fuel. Ended up convincing him to just run open loop and has been fine ever since. He has ID1000's just in case you wanted to know.

 

i'm running close loop using stock narrow band. Thanks for the info.

 

Muckman may have your answer, but I've also found a few other things that can cause this problem.
1.) check your battery and charging system, and be sure your air filter isn't clogged.
2.) check your spark plugs. any unusual patterns, colors or deposits may give you some insight.
3.) I constantly find tunes with a small area of the fuel map that isn't tuned correctly due to invalid readings from tip-in and idle recovery. It only presents a problem for a short duration before closed loop engages. Try starting in open loop and see if it hesitates for longer. If so, monitor it with a wideband, roll the throttle in 3rd gear around 1000RPM and see if there are any drastic variations between cells. If not, it's probably your injectors. Or a leaky valve.

 

Already make some improvement after remove 15% post start fuel adjustment. Now engine not hesitate at hot start. Thanks for the advice.