Who is running a boondockers side mount?

[mulot30th]

I seem to remember several things were going on at once with MulotTubo's sled that made it difficult to identify the real issue (valves, cam timing, ignition timing, bigger injectors working properly, possible wiring issues, etc), but I'm real glad to see everything's finally working.

The larger injectors are more difficult to tune with, and everything else must be working right in order to have success. In my opinion I think it's a mistake to start with the bigger injectors right at install before trying to tune and use the stock injectors. Starting with the stock injectors makes it much easier to be sure everything is working correctly (no vacuum leaks, cam timing is correct, wiring is ok, fuel pump/injectors are ok, etc.) and then if it's determined more fuel is necessary (which should only be necessary when running beyond 20-24 lbs, depending on elevation), then consider going to the bigger injectors.

Why would bigger injectors be so difficult to work with?

I tuned several LS1 engines with injectors ranging from 28.8# to 65# and never had 1/100th as much trouble as trying to make my apex to just run consistently using the BD box...

anyway... it just works great with stock injectors and pure logic box... and at 18psi.. there is still some left on the controller (I am at 5.5 out of 8 on boost fuel).

 

[efiguy]

Why would bigger injectors be so difficult to work with?

I tuned several LS1 engines with injectors ranging from 28.8# to 65# and never had 1/100th as much trouble as trying to make my apex to just run consistently using the BD box...

For smaller injector pulse conditions (idle, off-idle, light-throttle), the bigger injectors are more sensitive since more fuel is flowing per pulse, which can make precise fuel control more difficult to attain. The control box modifies the injector signal after the ECU sends it out, but the ECU is making adjustments based on the stock injector size. This can be a problem when the ECU is adjusting injector pulses for cold start conditions, then re-adjusts the pulses after the engine is warmed up. If we had direct control over the ECU so it could be reprogrammed (which is how most automotive reprogrammers work) for the bigger injectors, this wouldn't be a problem. For real high boost applications this season we are using an extra set of injectors so stock tunability is retained.

The control box shouldn't have any problem pulling enough fuel to allow the engine to idle fine with the larger injectors. The only issue may be the idle settings needs to be adjusted a couple numbers once the engine is done with it's cold-start sequence. I seem to remember your engine had a hard time idling with any fuel adjustment setting, which leads me to believe something else was likely causing problems (vacuum leak, wiring problem, bad sensor, bad cam or ignition timing, etc) - unfortunately I've seen several of these type issues occur when first trying to tune just after a turbo installation.

 

[mulot30th]

Back at the time I was able to make it idle much much better (but very rich) by hooking the big injectors DIRECTLY to stock ecm without the BD box making any adjustment...

As soon as I included the BD box in the loop... sled sometimes idles correctly... I shut it down and it would not idle next time (30 sec later)..

As an example:

I did a 15psi dyno pull with AFR adjusted to 11.5-1 WOT on my wideband... right after that we could not replicate the same afr by using the same settings... it would dip to like 10-1, or spike to 15-1... it was that crazy....

I hooked the stock injectors and the new box and dyno pulls were then always within a few 1/10th of an AFR ratio of each other...


But I like the idea of secondary injectors....