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Breakpoint setting for Deka 80# in AL92, TunerPro, 347

Unread postPosted: Sun Mar 01, 2020 12:39 pm
by JBasham
Hi everybody,

My old stock 5.0 H.O. with the TFS stage 1 cam and an Explorer intake was a sturdy motor for my road course car and I enjoyed learning to tune it with the Quarterhorse. But it was getting a little uneven on the compression tests and smoking quite a bit, so I changed it out. The new motor is the Blueprint 347 longblock (aluminum head version) and a Track Heat intake.

I'm am setting up parameters in a new AL92 bin, using TunerPro. I'm using EEC IV with a GFUB type box and the GUFX_180124.xdf strat. I'm using Ford TFI-IV ignition system with a Ford distributor. New MAF too, as you would expect.

I have the Siemens Deka 80# injectors from Power Adder Solutions in Raleigh. (I said "Hi" from Michael when I bought them.) Fuel pressure is set to 40 psi at idle.

The injector data page says breakpoint for these is 0.00002421. What value would you put down the #/rev colunn in FN 389? 5.2421?

Thanks for your thoughts.

Re: Breakpoint setting for Deka 80# in AL92, TunerPro, 347

Unread postPosted: Sun Mar 01, 2020 1:54 pm
by decipha
dont use the #rev function use the lbs/mass function just as the data has it

there is two breakpoint functions in the gufx def

Re: Breakpoint setting for Deka 80# in AL92, TunerPro, 347

Unread postPosted: Sun Mar 01, 2020 4:00 pm
by JBasham
Oh right, I remember now, thanks!

So, I search up the FUEL_MASS function (which is lbs) and put .00002421 in all the y cells

Then over in the FN389 function, AL92 has automatically converted all the Y cells for me to lbs/rev data.

Easy enough.

Thank you.

Re: Breakpoint setting for Deka 80# in AL92, TunerPro, 347

Unread postPosted: Sun Mar 01, 2020 5:24 pm
by decipha
yep np I try to make things easy

Re: Breakpoint setting for Deka 80# in AL92, TunerPro, 347

Unread postPosted: Sat May 23, 2020 10:58 am
by JBasham
Here's another question.

The Dekas are supposed to be really linear at low pulsewidth, right?

Then why is the low slope (101.49) so far away from the high slope (75.157)? That's like a third larger at low slope, right?

Because I seem to be crazy, crazy lean at low MAF voltages. And my MAF was flow-tested by Pro-M on their test bench, so I'm guessing my voltages are pretty close to right.

Re: Breakpoint setting for Deka 80# in AL92, TunerPro, 347

Unread postPosted: Sat May 23, 2020 11:06 am
by decipha
no they aren't linear down low hence the large difference in the slopes

They are very repeatable though so the injectors have excellent control.

If the maf transfer they gave you looks to be right then just dial in the injectors

Re: Breakpoint setting for Deka 80# in AL92, TunerPro, 347

Unread postPosted: Sat May 23, 2020 1:21 pm
by JBasham
Thanks.

I think the problem is, I'm a lousy mechanic.

I was just out in the shed putting a pressure gauge on the rail to check if I was still at 40 psi. I am.

But when I was putting things back together I saw a 3/8" port on the upper intake is wide open.

Let me fix that and try this again. D'oh!

Re: Breakpoint setting for Deka 80# in AL92, TunerPro, 347

Unread postPosted: Mon May 25, 2020 5:27 pm
by JBasham
Well plugging the air leak took care of the leaning out situation. Natch.

I wound up cutting the crank PW a lot. I had already calibrated it down for the 80# injectors replacing the 19s but I had to cut another 60 percent off even that.

Then I had to crank open the throttle idle gap a fair bit too. Completely shut was 180 tps and I had to go up to 260 or so to keep it in cold idle. I still have startup weirdness to sort out but it will get to warm stable idle and run in open loop okay.

Also since I'm a lousy mechanic I have to reinstall the lower intake so it doesn't leak oil out the rear valley. Uggg.

Anyway thanks as always for all your articles and your help. You da man!