EA injector slope calcs

TT331FB · 09-27-2005, 07:59 AM

Clint,

I ran a lengthy data log through this calculator. Pretty slick, by the way!

My tune has high slope 50, low slope 55, breakpoint 1.8(10)^-5

50# injectors, A9S

The calculator came up with 49.6, 54.2, 4.07(10)-5

What can I learn from this? I know that if I use the calculators breakpoint, my idle will be lean. Does this indicate a MAF problem?

Regards, Eric

86GT · 09-27-2005, 09:39 AM

First off, it seems as if you used the 'Breakpoint as a Scalar' option. Go to the injector tab and select the settings button. Then select the 'Breakpoint as a Function'.

The GUFB strategy uses a fixed breakpoint of 2ms. It can not be changed as far as I know. The function that is labeled as 'Injector Breakpoint' FN389 is actually a fuel trim under 1500RPM. This fallows the laws of diminishing returns. What I mean by this is, when at an idle (672) the fuel trim has a greater ratio of the overall PW than at 1500RPM. This essentially subtracts fuel at lower RPM's to compensate for the sloppiness of injectors at small PW's.

If you have your breakpoint set to 1.8e5 than either your injectors are pretty accurate or you modified the MAF curve to compensate.

By lowering the low slope you can raise the breakpoint. Just keep in mind that one is measured in lbs/rev and the other is lbs/hr. Small changes in the slope will cause big changes in the breakpoint.

After looking at the EA results that you posted, it looks as if you are running lean at around mid range PW's. The EA suggested a lower slope which will richen up the mixture in this range. It might help to plot the before and after slope line to see the difference.

TT331FB · 09-27-2005, 10:21 AM

I made the changes you suggested and the result was
49.9, 54.9, 3.05(10)-5

EA is suggesting changing the low slope from 54 to 55 and raising the breakpoint from 1.8 to 3(10)-5.

I'll give these numbers try.

Sendero · 10-09-2005, 11:22 PM

I've read a couple of different places that the Injector Breakpoint is hard coded at 2.0 ms in (pick your strategy) EEC. What about the EEC-V's, specifically a LLX3 Cobra EEC.

86GT · 10-09-2005, 11:46 PM

If it is an EECV then it is not a fixed value as far as I know. The breakpoint should be in the scalar section for the LLX3 and this is a good indicator of it not being fixed. At least this has been the the case on all non SHO taurus EEC's

09-27-2005, 07:59 AM	#1
TT331FB Member Join Date: Aug 2005 Posts: 53	EA injector slope calcs Clint, I ran a lengthy data log through this calculator. Pretty slick, by the way! My tune has high slope 50, low slope 55, breakpoint 1.8(10)^-5 50# injectors, A9S The calculator came up with 49.6, 54.2, 4.07(10)-5 What can I learn from this? I know that if I use the calculators breakpoint, my idle will be lean. Does this indicate a MAF problem? Regards, Eric __________________ TT331FB - T3/.6/.63 turbos, Spearco intercooler, 302/331 Mexican Block,AFR 185 heads, 80mm MAF, 75mm TB, 50# injectors, Tweecer, Track Heat intake, Comp cams roller blower grind, MSD BTM, DIY-WB, Yokogawa video display,T-56 tranny, 9" 3.5:1 Traclock, 4x disk brakes, TCP most everything, shelby roll bar. First fire up 2/14/2004.

09-27-2005, 09:39 AM	#2
86GT Member Join Date: Mar 2005 Location: Sacramento California Posts: 449	Re: EA injector slope calcs First off, it seems as if you used the 'Breakpoint as a Scalar' option. Go to the injector tab and select the settings button. Then select the 'Breakpoint as a Function'. The GUFB strategy uses a fixed breakpoint of 2ms. It can not be changed as far as I know. The function that is labeled as 'Injector Breakpoint' FN389 is actually a fuel trim under 1500RPM. This fallows the laws of diminishing returns. What I mean by this is, when at an idle (672) the fuel trim has a greater ratio of the overall PW than at 1500RPM. This essentially subtracts fuel at lower RPM's to compensate for the sloppiness of injectors at small PW's. If you have your breakpoint set to 1.8e5 than either your injectors are pretty accurate or you modified the MAF curve to compensate. By lowering the low slope you can raise the breakpoint. Just keep in mind that one is measured in lbs/rev and the other is lbs/hr. Small changes in the slope will cause big changes in the breakpoint. After looking at the EA results that you posted, it looks as if you are running lean at around mid range PW's. The EA suggested a lower slope which will richen up the mixture in this range. It might help to plot the before and after slope line to see the difference. __________________ EEC Analyzer A9M, TwEECer, 306ci, 73mm C&L w Tuner Tube, Cobra Intake, 42# inj, Edelbrock 6037, E303 cam, 155 fuel pump, FPR, 70mm TB, E-Fan, 3.55 gears, Powerdyne 9psi actual 5psi...way more.

09-27-2005, 10:21 AM	#3
TT331FB Member Join Date: Aug 2005 Posts: 53	Re: EA injector slope calcs I made the changes you suggested and the result was 49.9, 54.9, 3.05(10)-5 EA is suggesting changing the low slope from 54 to 55 and raising the breakpoint from 1.8 to 3(10)-5. I'll give these numbers try. __________________ TT331FB - T3/.6/.63 turbos, Spearco intercooler, 302/331 Mexican Block,AFR 185 heads, 80mm MAF, 75mm TB, 50# injectors, Tweecer, Track Heat intake, Comp cams roller blower grind, MSD BTM, DIY-WB, Yokogawa video display,T-56 tranny, 9" 3.5:1 Traclock, 4x disk brakes, TCP most everything, shelby roll bar. First fire up 2/14/2004.

10-09-2005, 11:22 PM	#4
Sendero Im gonna show her my... Join Date: Dec 2004 Location: Somewhere providing FREE tech support. Posts: 4,269	Re: EA injector slope calcs I've read a couple of different places that the Injector Breakpoint is hard coded at 2.0 ms in (pick your strategy) EEC. What about the EEC-V's, specifically a LLX3 Cobra EEC. __________________ I heard it on the internet, so it must be true. "I believe that a person's moral compass can be determined by how he references free men the right to defend themselves." T. Nugent "An armed society is a polite society. Manners are good when one may have to back up his acts with his life." R. Heinlein "Never argue with an idiot. They drag you down to their level, then beat you with experience." -Unknown

10-09-2005, 11:46 PM	#5
86GT Member Join Date: Mar 2005 Location: Sacramento California Posts: 449	Re: EA injector slope calcs If it is an EECV then it is not a fixed value as far as I know. The breakpoint should be in the scalar section for the LLX3 and this is a good indicator of it not being fixed. At least this has been the the case on all non SHO taurus EEC's __________________ EEC Analyzer A9M, TwEECer, 306ci, 73mm C&L w Tuner Tube, Cobra Intake, 42# inj, Edelbrock 6037, E303 cam, 155 fuel pump, FPR, 70mm TB, E-Fan, 3.55 gears, Powerdyne 9psi actual 5psi...way more.