Injector Life.

[John Dammeyer]

Hi all,

I think,  but I'm not sure if I am having an injector life problem.
We'll know better tomorrow when the engine is cold but it seems like
after a period of running the injectors will no longer open and close
precisely.  What happened today was that we ran the engine for about 30
minutes at full load and 5400RPM.  Lot's of acceleration/decel etc.  O2
sensor was reasonable and we achieved the max RPM expected considering
prop load. We then brought the engine back down to an idle and let the
temperature stabilize from 205 to 185.  After that we turned the engine
off.  A few hours later,  we did some more runs and suddenly found that
the engine would barely idle.  Pulse widths verses MAP etc. to the
injectors were consistent with previous runs and the engine stumbled
until about 2000RPM.

To me it sounds like one or two stuck injectors because at idle the O2
sensor was off the scale as far as lean mixture was concerned.  Pulling
a plug from the high power run showed nice colouring and pulling a plug
from the rough idle did not show carbon so I am assuming the O2 sensor
was correct.

Begs the question,  what could be up with the injectors.  They are stock
Honda Injectors for the 1600CC engine,  11.5 Ohms roughly and we use a
7.5 Ohm resistor in series with them because we found that they wouldn't
close fast enough to create a 1.25ms pulse which is about all we need at
idle.  Once we added the resistors in series with each injector we were
able to easily get our low and high pulse rates.  I don't have data
sheets for the injectors used in Honda.  Only what the after market
information states which is that it's a 141.5 gm injector at 3 bar 11.6
ohms.

If that number is the delivery rate at 80% duty cycle then I'm right on
the money for fuel usage and timing calculations.   If it's the delivery
rate for a 100% duty cycle then I'll never get full power at 80% duty
cycle but at the moment that's not my problem.

Any ideas?  Any place on the WEB that has injector specifications?

Thanks,

John