Hondata

Hi guys,

I am experiencing bad misfiring at partial throttle at high rpms. It runs perfect at WOT but bad misfiring happening during TPS between 10% to 50% from rpms 5000 to 7000. Anyone with similar problems before? Could it be mechanical problem like spark plugs and distributor fault?

Low rpms at part throttle runs perfect, full throttle to 8000rpm redline runs perfect. As this is a circuit car, partial throttle in mid corner at rpms ranging from 4500rpm to 7000rpm is important, the engine starts to misfire and stutter and suffers from power loss. Power comes back to normal when the throttle is fully depressed. Its puzzling.


Engine specs:
B20 block
B16a head
Jenvey ITB
Jun2 cams

Its a spark problem, check your plugs and wires. This was happening to me just the other day. it turned out to be my spark plugs. the metal part that the plug wire pops onto is a threaded piece that can be "unscrewed" apparently vibrations had unscrewed these on two of my spark plugs which obviously created a weak spark. I would imagine if I screwed them back down it would have fixed it but I was replacing them anyway. so I put in new ones and the problem went away.

I didnt bother looking at the plugs for the longest time because it didnt make sense to me that it worked fine at full throttle or at high RPM's. but once I replaced them it was fine

if its not your plugs or wires, or rotor or cap, but most likely plugs or wires.

How long has it been running on your current map? Check the plugs, and tubes for anything that might cause the spark to find a closer ground. I've had a tube seal go bad, and the tube fill with oil causing a misfire before.