ZR-1 Net Registry Forums - View Single Post

Paul Workman · 07-17-2015

Curious about the current draw/limits for (FIC) injectors, I spoke with Jon (at FIC) briefly about your problem, and he mentioned that there have been cases where customers have inadvertently swapped the primary and secondary injector connectors.

Thinking about that, if your LT5 is NOT modified for secondary deletion, then I would expect what you are experiencing to be the case:

Primary injector not running at idle or little throttle causing a constant miss at lower throttle settings
Bogging when you "step on it"*
WOT works normal (aka "Screams, as you said!)

*With the primary injector in the secondary runner, fuel would not be getting to the cylinder at low throttle due to the SPT plate being closed. However, fuel would back up and pool in the injector housing runner; possibly flooding the runner, depending on how tight the SPT plate seals (and possibly causing other low speed issues too, should the runner fill and run over with fuel to back-fill and spill into the plenum where it would get drawn in by other cylinders...not good!

However, when the secondaries are signaled ON and the SPTs open, initially a slug of raw fuel drops into the cylinder, temporarily flooding it (hence a bog/stutter/miss/blue smoke, etc would likely occur. In a few seconds, the cylinder would pump out the excess fuel and with both injectors now running the engine would perform in normal WOT fashion.

Note: For LT5s modified to delete the SPTs, it shouldn't matter if the injectors are swapped, as they both run full time except at idle, but not having SPT restrictions, there will be no fuel pooling regardless, and it should idle fine, I would think.

If having the two injectors swapped is NOT thee problem, you will need to wring out the wiring/connector to the injector.

It might be easier to pull the plenum than mess with the relay and ECM connector pins, and thereby gaining direct access to the injector itself. Grounding the (black/yellow wire) side of the connector and providing an instantaneous on-off connection to the other side to power the injector, you should hear a audible "click" which would indicate the injector should be working normally...should be.

Page 6E3-A-5 (1990 FSM) is the scematic to help guide your troubleshooting.

Update when you can...

07-17-2015	#18
Paul Workman Join Date: Nov 2007 Location: Squires (near Ava MO in the Mark Twain N'tl Forest) - Missouri Posts: 6,466	Re: LT5 miss at all speeds Curious about the current draw/limits for (FIC) injectors, I spoke with Jon (at FIC) briefly about your problem, and he mentioned that there have been cases where customers have inadvertently swapped the primary and secondary injector connectors. Thinking about that, if your LT5 is NOT modified for *secondary deletion, then I would expect what you are experiencing to be the case: Primary injector not running at idle or little throttle causing a constant miss at lower throttle settings Bogging when you "step on it" WOT works normal (aka "Screams, as you said!) With the primary injector in the secondary runner, fuel would not be getting to the cylinder at low throttle due to the SPT plate being closed. However, fuel would back up and pool in the injector housing runner; possibly flooding the runner, depending on how tight the SPT plate seals (and possibly causing other low speed issues too, should the runner fill and run over with fuel to back-fill and spill into the plenum where it would get drawn in by other cylinders...not good! However, when the secondaries are signaled ON and the SPTs open, initially a slug of raw fuel drops into the cylinder, temporarily flooding it (hence a bog/stutter/miss/blue smoke, etc would likely occur. In a few seconds, the cylinder would pump out the excess fuel and with both injectors now running the engine would perform in normal WOT fashion. Note: For LT5s modified to delete the SPTs, it shouldn't matter if the injectors are swapped, as they both run full time except at idle, but not having SPT restrictions, there will be no fuel pooling regardless, and it should idle fine, I would think. If having the two injectors swapped is NOT thee* problem, you will need to wring out the wiring/connector to the injector. It might be easier to pull the plenum than mess with the relay and ECM connector pins, and thereby gaining direct access to the injector itself. Grounding the (black/yellow wire) side of the connector and providing an instantaneous on-off connection to the other side to power the injector, you should hear a audible "click" which would indicate the injector should be working normally...should be. Page 6E3-A-5 (1990 FSM) is the scematic to help guide your troubleshooting. Update when you can...