My setup: 550/1600, 7-7-4 overlap, 40% transistion %,
transition ms was (850/1600) * 1.5 = .797 ms. This is the accepted method to calculate transition ms.

I tested these transistion ms settings: .40, .60, .797, and 1.0. Used
third gear from about 2500 to about 5000 rpm by flooring the throttle.

Used the chart format to review the logged results.
With all of these tested setting, when the secondaries came on, they jumped up high and then went flat for a while. During this time the primaries took a nose dive and then recovered up some. After this they smoothed out and eventially crossed over each other.

Of the 4 test, the .40ms gave the smoothest tranistion, and it needs to be reduce even more.

After these tests I will test low load transitions.

 

what was the set up for 850/1600? From your post it loos as though you went from 850/1600 to 550/1600. I have 850/1680 and i know the over lap isent right. So am ordering the data logit to do it right my self. If you dont mind just giving me a good place to start.

Thanks

Adam

 

I went from 550/1200 to 550/1600 and started looking at more areas of the DL that wasn't needed for 550/850 or 550/1200 injector sets.

You are being confused about this formula (850/1600) * 1.5 = .797 ms used for secondaries. Oringinaly I had (850/1200) * 1.5 = 1.063ms.

 

The previous tests were done with the stock Primary/Secondary Transistion % at 40%. But all heavy throttle tests showed 48% at where it actually occured. Light throttle was about 52%.

Using the Datalogit, I changed the Primary/Secondary Transistion % to 30%. Retesting shows that the transitions are now at 38%. My car still drives fine.

What does thid mean?
The PFC is about 10% slow in actual doing the transition.

Not confirmed, but: if the secondary ports are flowing some air but only the primaries injectors are flowing fuel, then the fuel air mixture propably isn't as well mixted as if both injectors are flowing.

I'll be driving it this way for a while to give it a good test.

 

as usual Chuck, a very interesting post.

i am dealing w 2 problems that might be related... the first being looking at a line chart of my base fuel i have a 3 or 4 line bulge that resettles to a moderate uptrend while delivering smooth AFRs. the bulge at p15 point 9 goes from 16.8 Ms to 28.8 at p15 n10. something of a transition problem? i am 850/1600, 40%, .996 ( i have tried .796 and 1.5), w 9 8 5 (also tried other #s). i also have a brief stutter going in to boost and then it smooths out and all is well as far as performance and afrs.

i just checked my log from an hour ago and while set at 40% my secondary comes on at 48%. i have not changed the 40% setting and will do so on my next run. my mapwatched Inj Fr Pr is at 9 w the secondary at zero. the next chart data shows 8 on the primary and 1 on the secondary.

i will look forward to adjusting the transition and found your observation very interesting.

howard coleman

 

Perhaps this is why Mazda had the secondary intake butterflies ... amazing how well the car can run with the secondary ports always breathing

 

Howard,

One thing about using the CHART format, you have to pre-edit the log to remove any N column overlapping else it screws up the readings. As you start a log under boost and then let off at some rpm, the vacuum readings can fall back over the boost readings.

Example you have a boost reading of 90 at 4000 rpm (N10) on P row 17 and let off the throttle at 5000 rpm. As your revs drop back to 4000 while off throttle, it records a vacuum reading in P row 2 at N10. The map watch would show these two points in different cells. But the chart uses the average of the two readings for the "Y" axis and thus is inaccurate.

Thus you edit out the log readings that happen after you get off the gas.

I made a saved MAP WATCH that displays RPM, IGL, BOOST, AN1 WIDEBAND, KNOCK, and INJ DUTY CYCLE. On my INJECTOR CHART I only show three lines;
INJ FR PRI, INJ FR SEC, and INJ DUTY. As you know when you slide the "Y" axis bar across the chart, the map watches show the actual value for those points on the chart. This way you can see if your injectors are working with smooth curves and where lean or rich spots are.

I have to give credit to Barry Bordes in New Orleans who got me interested in using the chart function!

 

Chuck,

I've been using .750 for about a year now on my 860 / 1680 Combo. Seems pretty lose to the calculated .767 . I hit that number through testing.

Also, aren't you using 1680s, not 1600s?

Tony

 

I have the RX-7 Store kit which they call 1600s. Someone else told me they are really 1680s.

My old 1200s with .10 lag were flowed at that and I had a perfectly tuned map using the 550/1200 set. All four injectors were new and have less than 8000 miles on them.

After installing the 1600, I set them up as 1680s with .40 lag. This caused my AFRs to go lean. Testing various combos, 1600 with .20 lag gave the closest AFR readings to my previous AFR tunings. My new FPR is setup almost exactly like the stock one was. Pressures at idle and 0 boost are no more than 1 psi different.

Then I started testing as in this thread.

This caused my AFRs

 

They are 1680's. What color are they? Teal, bluish?

 

Mine have avery light gray top.

 

I used to have a lean stumble when I installed the 1300 sec. with the stock 550 primaries. It would occur at the transition point. I used the 7,7,4 overlap setting to help smooth it out but it was never gone completely. I decided to increase my primaries to 775 with some 1200 cc secondaries and the stumble was complete gone. It ran just like stock with 550/850 setup. I set all my overlap and transition settings back to stock and no problems.

it seems that the power fc still likes the original ratio between pri and sec. choosing inj. sizes to keep this ratio is the best way to start. obviously at some point you will have an imbalance with very high fuel needs that require 1680 sec inj.

Mike