At 11:22 AM 7/26/01 -0500, you wrote:
>Just my observation, but it even seems like FMS#19s didnt work well
>on my truck either. Put the stock injectors back on and I think it runs
>better. Kyle 93 Dakota 4x4 V6
Similar experience on my OBDII, modded (cam, MPI) 5.2L.
I think that the FMS#19s have a different spray tip (pintle type) than
the stock Siemens (disc type). The pintle tip sprays a narrower pattern
of gas than the disc type (wide spread). Appropriate use of which type
is largely dependent on the head design.
In addition, I believe that the FMS#19s are calibrated at 38 psi whereas
the Siemens are calibrated at 43.5 psi. This would mean that the
FSM#19s have roughly the following calibrations: @45 psi=20.67#/hr,
@ 55 psi= 22.86#/hr, @ 61 psi=24.07#/hr., @ 95 psi=30.04#/hr.
The pattern of movement on my AF gauge was very different from that
with the stock injectors as the pcm attempted to adjust the pulsewidths
for a stoich mixture.
Elevated fuel pressure can hurt performance because increased forces
in the injector make it open more slowly and close faster. This may
cut down the net fuel sprayed by the injector. Scanner readouts of
6 runs at the track (especially in the first 1/8-mile) would seem
to support this.
At idle and part throttle, you do get the sensation that the engine
has a very lumpy cam. Also, the sound from the exhaust tips at revs
is very near that from a 440.
One possible, personal consolation is that the FMS#19s have the same
type of spray tip as those used on my '85 Dodge Shelby Turbo Charger.
I just need to check on how close their calibrations are.
Bob
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