Reply To: GD250N – Hanging Revs and Stalling when Throttle opened quickly
After finding an appropriate socket, the spark gap was out of spec by a quite a bit (I think) at about 1mm, corrected it down to 0.7mm and cleaned it off a bit.
didn’t look obviously rich or lean to me, let me know what you think:
Ran basically the same after the adjustment though, no misfiring at above 4k but misfiring below (misfiring then surging when rolling in gear), worsening with temperature. I also did some data slewing (modifying ECU parameters at runtime) and offset the IAC valve to close a little bit, idled with the same stability but at 1400~ instead of 2000~, still stalling when opening the throttle too quickly. (Haven’t yet checked if rev-hang improves with this modification while riding)
Additionally, I noticed the engine speed to be unsteady when the throttle is held half open in neutral, going up and down (not misfiring) which might mean a fuel pressure issue? I’ll see if I can find a way to measure fuel pressure somehow,
I currently think that it’s either
– Fuel pump (weak and or overheating)
– Ignition coils (heat related?)
– Clogged Injector? (Could I clean it?)
I can’t really gauge which is most likely given symptoms though, would be happy to hear your thoughts!
sorry for another long post!