[Diy_efi] Iridium plug problems

[Tim Marsteiner]

Trying to debug an intermittent problem with one of my
motorcycles. It's a big V-Twin using an alpha-N efi
system with COP.

Every so often perhaps once a month it bogs down bad
and starts to backfire severely. As soon as I pull the
clutch in it stalls and won't restart. This typically
happens 5-10 minutes after startup. The problem has
always "fixed itself" after letting the bike sit for
15-20 minutes. So it appears that heat soak is
"fixing" the problem.

I am running an open loop tune and my data logs
indicate TPS, IAT and engine temp sensors are fine.

I do notice my CHT temp gauge starts going up on cyl
#1 perhaps 20-30 F. Of course it does not run very
long in this condition. Also, on a recent ride, just
as the problem began, one of my riding buddies
reported flames coming out of the front cylinder's
pipe. Nice. I replaced the front cylinder's COP and
man I thought that was it ... it had made it over 2
months without a problem until yesterday. 

Since heat soak seems to fix it I am guessing it is
not some kind of harness short. Plus no DTC(s).

Last spring I changed to iridium plugs. It never
happened before this, but it ran fine for several
months with these plugs before the problem started.

A while back there was a discussion on platinum plugs.
Can iridium plugs also put more stress on ignition
components? And does this apply to a coil on plug
system? 

And now the $400 question. If they do put more stress
on the system could it cause the coil to draw
excessive current from the ECU's coil drivers? 

Thanks,
Tim



		
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