I have a question of how the injector overlap effects the maps. I have a stumble at 3500 and have am using 6/5/2 as My setting. I then tried 5/3/2 and the stumble moved up in the RPM range and got worse. I am going to try 7/7/4 and see if it works but am I changing the fuel in the maps by doing this? I am going to see if moving the transition from 40 to 50 might help but I wanted to try the overlap settings first.

Thanks for anyone who has Datalogit experience.

 

I run 7/7/5 to get rid of stumble with the 1600 secondaries. Also had to run higher than stock when I ran the 1300's.

Helps to have a wideband to tell if lean or rich

 

I am using the Tech Edge and have almost all the fuel tuned. I will try the 7/7/5.

Do You know what these settings actually do?

Thanks

 

Overlap is the period of shaft revolution or amount of crank angle the secondaries are placed online before the primary inj duty cycle is reduced. Multiply the number in the box by 1/12 and that is the number of crank revolutions of overlap.

 

Also try adjusting SECONDARY TRANSITION.

Recalculate it as: (1.500ms) * (850/ new secondary size)

As with any unsure change, do one at a time and test drive it.

 

Thanks.

 

cewrx7r1, Are You saying that for a 1600cc secondary?

(1.500ms) * (850/ new secondary size)

(1.500ms) * (850/1600cc) = .7969

.7969 Sec transition in (ms)



I am using .968 right now for Sec transition time is this wrong?Will this effect AFR`s when I change it? Thanks for the help again.

Steve

 

While I have Your help, here are My injector settings for 750cc primary and 1600 secondary.

front primary 73.3 0.03

front secondary 0.45

rear primary 73.3 0.03

rear secondary 0.45


Pri/sec transition 40.0

Sec transition .968

 

I'm running about the same sec transition as you are and it works well with my 1600's.

The sec transition is the initial "on time" or duty for the secondary injector so Chuck's advice appears to provide the same initial secondary fuel delivery as the stock secondaries. Since the primaries reduce by the same amount during transition the overlap settings are what prevent the lean condition when the secondaries attempt to start flowing fuel.

 

I am just stating what is in the DATALOGIT manual and what was posted on it's forum on what and how secondary transition time is adjusted.

I have 550 primaries with 1200 secondaries and had not changed either SECONDARY TRANSITION or INJECTOR OVERLAP when they were installed. All ran well until....

When I was doing some mods lately, I discoverd that one of my secodary injector air bleeds (deflectors) was broken with one of the three legs missing. I pulled both out, cut off all the legs, and reinstalled them (holds the seal in place).

After that light throttle responce was bucking a little. I first tried 5-4-2 overlap and it helped some. Then tried 7-7-3 with little change.

Changed it back to stock but with a recalculated SECONDARY TRANSITION for 1200s (1.063ms). It was best of the tests but still off sometimes.

Now I am running 1.063ms with 5-4-2 and it is almost perfect. I have stock intake ports and running stock twins.

Did one simple AFR log test afterwards, and did not see any changes other than normal deviations.

 

Thanks again Guys.

The only problem I am having now as the car becomes finer tuned is that My 40mm wastgate cant hold boost anymore in 3rd and I am overshooting My boost setting (19) by 5PSI as I hit redline in 3rd. The AVCR is set at 20 duty which is minimum, but I wont complain as it is pulling really hard and my maps are good to about 27 (I hope).