Just got back from a drive. I had let it warm up a bit before we went, then shut it off. Went to start it up... and cranking. And cranking. Still cranking. Tried again, held the throttle wide open, then it stuttered and popped to life, had to feather the gas and open it way up to get it to come out of it. Once it came out of closed loop it ran and idled properly. Got it out on the road, drove alright. When I kept it at constant throttle it would start to stutter and buck a little bit, a heavy right foot would clear it up. It's getting way too much fuel, so I need to make the JET software communicate properly with my PC so I can learn how to tune it, as I can't get it to open any files. Turns out these injectors are not quite the same as stock. Got the truck out on the freeway, MAN, is it gutless at WOT. Wanders really bad on the freeway, really needs tie rods. Doesn't wander bad on the highway though.
Definitely needs a tune now, but at least I guess I have a baseline to improve over. Disappointing for a fuel injected big block. Lol.
454C2500Longbed,
Thanks for the photos. I looked closely at the underneath of your distributor cap, and it looks
like it is just starting to show the discoloration that was evident in the cap below, which also
was causing a no-start situation:
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As for your new injectors, I want to be clear about the correct terminology.
When you engine is first started, and as long as your O2 sensors are below ~600°F, the
computer will be making all fueling and timing calculations based *only* on the stored
(default) tables in memory. This is referred to as Open Loop.
Once the O2 sensors are up to temp & the engine coolant is above a certain threshold, the
computer goes Closed Loop, and the fueling is now driven by feedback signals from the
operational O2 sensors.
In English, the tables in your VCM are tailored to the original injectors, so whatever net difference
there is between your new injectors versus the factory ones will be the error during Open Loop
operation. Once the system goes Closed Loop, then assuming the difference is within the limits
that the computer is allowed to deviate from the default, then your system will 'tune' around
this difference. Given this, I would expect that your truck won't drive quite right when cold,
but once it goes Closed Loop it may run just fine.
Definitely get your tuning setup operational, and once you figure this out, then all future tuning
down the road will actually be fun. Just that steep learning curve in the beginning.
Fingers crossed that you get this all sorted out sooner rather than later.
Best of luck --
