Fuel Equilibrium Intake Surface FN1321

86GT · 11-01-2005, 09:21 PM

Here is how the GUFB book states:

Transient Fuel is variously referred to as manifold wall wetting, puddling, filling, fuel film condensation/evaporation.

A liquid fuel film resides on the walls of the intake manifold. The film mass varies primarily with manifold absolute pressure and manifold wall temperature. During steady state conditions, the film mass is constant. The rates of condensation and evaporation on the manifold walls are equal.

During transients, the film mass changes creating air/fuel ratio errors. During accelerations, the film mass increases. Fuel will condense faster on the manifold walls until equilibrium is reached. In an uncompensated system at stoichiometry, fuel is diverted from the cylinders, resulting in a momentary lean condition.

During decelerations, the film mass decreases. Fuel will evaporate faster from the manifold walls until equilibrium is reached. In an uncompensated system at stoichiometry, fuel is added to the cylinders, resulting in a momentary rich condition.

The problem is magnified in closed loop fuel systems because the fuel control will incorrectly chase the transient air/fuel excursions.

INTENT

The Transient Fuel Compensation Strategy (TFC) augments the closed/open loop fuel control to keep cylinder events at the desired air/fuel ratio during all engine transients. The goals are:
To eliminate lean air/fuel excursions during accelerations.

To eliminate rich air/fuel excursions during decelerations.

I personally have found the MEFTRA scalar more valuable so far. This is the Equilibrium Accel multiplier. It allows for riching the mixture during accel.

The MEFTRD scalar is the Deccel Equilibrium multiplier. This one helps in the decel popping which is caused by to much fuel in the decel.

I am starting to play with the Equilibrium table to fine tune the Accel at certain loads. Larger numbers I believe are to richen the mixture. You just have to keep in mind that by raising the number you will richen the mixture on accel and lean the mixture on decel. I am still playing with the table to prove what I am seeing.

Another key point for those of you that have modified the Load scale (normalizers FN071), this will affect the Equilibrium tables and throw it way out of whack.

When I changed my load scale (FN071) the car ran completley different during non steady throttle states. I then went to the Equilibrium table and moved the numbers around to mimic the factory table and the car drove much better. So for those of you that do not have access the the Equilibrium tables, I would not recommend changing function 071.

QWKSNKE · 11-02-2005, 02:57 AM

Thanks Clint

Dale McPeters · 11-02-2005, 07:04 AM

One thing to add is that this and the manifold volume, air charge WOT multiplier on newer strategies can have a huge effect on cars that run a blower etc......in a street/strip application.

For example the air charge WOT multiplier on the '03 Mach 1 strategy
seems to work best at 1.9 with a blown setup. The stock setting is "1.1001".

While the stock setting for the manifold volume on the '03 Mach 1 is set at "0" in the stock calibration. IMHO the manifold volume is used more in the older strategies '96-'98,'99 maybe?

86GT · 11-02-2005, 08:29 AM

The Equilibrium Accel multiplier is:

X3Z= 1.5
A9L= 1.203

Both of the Equilibrium deccel multipliers are set to 1.0

The Equilibrium tables are also different.

Dale have you messed with the Equilibrium table? If so which way is rich and lean? I have been playing with small numbers so that I do not screw things up. It looks as if I will need to make bigger steps.

Dale McPeters · 11-02-2005, 08:45 AM

Clint,

I have played with them on the EEC-IV, but I have been so busy with some
of the EEC-V stuff lately that I am brain dead....

I will have to look at my notebook later to see what I wrote down.

Maybe >
In the table
Lower numbers = less
Higher numbers = more

But do not quote me on that as I am not sure at the moment, brain dead you know. I will try to take a look tonight if I have time.

Dale McPeters · 11-02-2005, 09:03 AM

Cint,

One other thing on the A9* eec's take a look at the
intake filling HG. I think it is set at 1.999.
Do not remember what effect if any that this had......

gt90stang · 11-02-2005, 01:55 PM

Clint,

Thanks for the input. However i'm a little confused because our injectors are sitting very close to the intake valve and there isn't much intake tract do cause this effect. I think it would be way different with TB injection, but I find it hard to believe that it would be more than a fairly low level adjustment?

BTW, I have changed FN071, 072A and 085.

With timing reduction I have much improved my problem and now only have a slight bucking/misfiring issue between 1400-1500 RPM in second gear.

Don

86GT · 11-02-2005, 03:05 PM

You have to remember that when the intake valve closes the injector may still be spraying. During this time one of the other cylinders is drawing fuel in. This vacuum caused by the other cylinder will cause the peddled fuel in the cylinder with the valve closed to go back up the intake. Of course this only happens at high RPM and injector PW.

Also it does not only apply to fuel. Think about the moisture in the air. When the moisture is pulled out the air becomes denser.

gt90stang · 11-02-2005, 08:52 PM

Clint,

I'm pretty sure my issue is a steady state one because pulling timing from the tables seems to be working. Transient wise I get good response.

On my setup I know the injectors shutoff before the intake valve closes and I also wait for the exhaust valve to close before injecting.

BTW, I think you meant less dense with lower moisture content?

Don

86GT · 11-03-2005, 12:47 AM

Yep Yep

If you are only seeing the problem at steady state then this will not apply to you.

11-01-2005, 09:21 PM	#1
86GT Member Join Date: Mar 2005 Location: Sacramento California Posts: 449	Fuel Equilibrium Intake Surface FN1321 Here is how the GUFB book states: Transient Fuel is variously referred to as manifold wall wetting, puddling, filling, fuel film condensation/evaporation. A liquid fuel film resides on the walls of the intake manifold. The film mass varies primarily with manifold absolute pressure and manifold wall temperature. During steady state conditions, the film mass is constant. The rates of condensation and evaporation on the manifold walls are equal. During transients, the film mass changes creating air/fuel ratio errors. During accelerations, the film mass increases. Fuel will condense faster on the manifold walls until equilibrium is reached. In an uncompensated system at stoichiometry, fuel is diverted from the cylinders, resulting in a momentary lean condition. During decelerations, the film mass decreases. Fuel will evaporate faster from the manifold walls until equilibrium is reached. In an uncompensated system at stoichiometry, fuel is added to the cylinders, resulting in a momentary rich condition. The problem is magnified in closed loop fuel systems because the fuel control will incorrectly chase the transient air/fuel excursions. INTENT The Transient Fuel Compensation Strategy (TFC) augments the closed/open loop fuel control to keep cylinder events at the desired air/fuel ratio during all engine transients. The goals are: To eliminate lean air/fuel excursions during accelerations. To eliminate rich air/fuel excursions during decelerations. I personally have found the MEFTRA scalar more valuable so far. This is the Equilibrium Accel multiplier. It allows for riching the mixture during accel. The MEFTRD scalar is the Deccel Equilibrium multiplier. This one helps in the decel popping which is caused by to much fuel in the decel. I am starting to play with the Equilibrium table to fine tune the Accel at certain loads. Larger numbers I believe are to richen the mixture. You just have to keep in mind that by raising the number you will richen the mixture on accel and lean the mixture on decel. I am still playing with the table to prove what I am seeing. Another key point for those of you that have modified the Load scale (normalizers FN071), this will affect the Equilibrium tables and throw it way out of whack. When I changed my load scale (FN071) the car ran completley different during non steady throttle states. I then went to the Equilibrium table and moved the numbers around to mimic the factory table and the car drove much better. So for those of you that do not have access the the Equilibrium tables, I would not recommend changing function 071. __________________ 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.

11-02-2005, 02:57 AM	#2
QWKSNKE 3v's are slow Join Date: Dec 2004 Location: Here and There Posts: 17,152	Re: Fuel Equilibrium Intake Surface FN1321 Thanks Clint

11-02-2005, 07:04 AM	#3
Dale McPeters 5.0 Block/Walnut Cracker Join Date: May 2005 Location: Working.... Posts: 2,409	Re: Fuel Equilibrium Intake Surface FN1321 One thing to add is that this and the manifold volume, air charge WOT multiplier on newer strategies can have a huge effect on cars that run a blower etc......in a street/strip application. For example the air charge WOT multiplier on the '03 Mach 1 strategy seems to work best at 1.9 with a blown setup. The stock setting is "1.1001". While the stock setting for the manifold volume on the '03 Mach 1 is set at "0" in the stock calibration. IMHO the manifold volume is used more in the older strategies '96-'98,'99 maybe? __________________ '14 Dodge Challenger SRT8 392 6-speed

11-02-2005, 08:29 AM	#4
86GT Member Join Date: Mar 2005 Location: Sacramento California Posts: 449	Re: Fuel Equilibrium Intake Surface FN1321 The Equilibrium Accel multiplier is: X3Z= 1.5 A9L= 1.203 Both of the Equilibrium deccel multipliers are set to 1.0 The Equilibrium tables are also different. Dale have you messed with the Equilibrium table? If so which way is rich and lean? I have been playing with small numbers so that I do not screw things up. It looks as if I will need to make bigger steps. __________________ 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.

11-02-2005, 08:45 AM	#5
Dale McPeters 5.0 Block/Walnut Cracker Join Date: May 2005 Location: Working.... Posts: 2,409	Re: Fuel Equilibrium Intake Surface FN1321 Clint, I have played with them on the EEC-IV, but I have been so busy with some of the EEC-V stuff lately that I am brain dead.... I will have to look at my notebook later to see what I wrote down. Maybe > In the table Lower numbers = less Higher numbers = more But do not quote me on that as I am not sure at the moment, brain dead you know. I will try to take a look tonight if I have time. __________________ '14 Dodge Challenger SRT8 392 6-speed

11-02-2005, 09:03 AM	#6
Dale McPeters 5.0 Block/Walnut Cracker Join Date: May 2005 Location: Working.... Posts: 2,409	Re: Fuel Equilibrium Intake Surface FN1321 Cint, One other thing on the A9* eec's take a look at the intake filling HG. I think it is set at 1.999. Do not remember what effect if any that this had...... __________________ '14 Dodge Challenger SRT8 392 6-speed

11-02-2005, 01:55 PM	#7
gt90stang Member Join Date: Aug 2005 Posts: 72	Re: Fuel Equilibrium Intake Surface FN1321 Clint, Thanks for the input. However i'm a little confused because our injectors are sitting very close to the intake valve and there isn't much intake tract do cause this effect. I think it would be way different with TB injection, but I find it hard to believe that it would be more than a fairly low level adjustment? BTW, I have changed FN071, 072A and 085. With timing reduction I have much improved my problem and now only have a slight bucking/misfiring issue between 1400-1500 RPM in second gear. Don

11-02-2005, 03:05 PM	#8
86GT Member Join Date: Mar 2005 Location: Sacramento California Posts: 449	Re: Fuel Equilibrium Intake Surface FN1321 You have to remember that when the intake valve closes the injector may still be spraying. During this time one of the other cylinders is drawing fuel in. This vacuum caused by the other cylinder will cause the peddled fuel in the cylinder with the valve closed to go back up the intake. Of course this only happens at high RPM and injector PW. Also it does not only apply to fuel. Think about the moisture in the air. When the moisture is pulled out the air becomes denser. __________________ 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.

11-02-2005, 08:52 PM	#9
gt90stang Member Join Date: Aug 2005 Posts: 72	Re: Fuel Equilibrium Intake Surface FN1321 Clint, I'm pretty sure my issue is a steady state one because pulling timing from the tables seems to be working. Transient wise I get good response. On my setup I know the injectors shutoff before the intake valve closes and I also wait for the exhaust valve to close before injecting. BTW, I think you meant less dense with lower moisture content? Don

11-03-2005, 12:47 AM	#10
86GT Member Join Date: Mar 2005 Location: Sacramento California Posts: 449	Re: Fuel Equilibrium Intake Surface FN1321 Yep Yep If you are only seeing the problem at steady state then this will not apply to you. __________________ 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.