blue87

iTrader: (2)

I thought I would share a spreadsheet that I threw together to play around with fine tuning the base fuel map...

1st of all if anyone decides to use it, use common sense and don't just dump the values into your car without thinking about it. I consider this a tool just like a screwdriver so don't stick it in your eye

I put the base recalculated fuel map in the left box on the sheet. I have three areas set up for log data. Once the vehicle is warm I drive around trying to hit as many parts of the map as possible moving the throttle slowly to keep the load transitions smooth.

I set up a conditional statement that uses the average A/F data map watch from the largest hold out value first as it should be most accurate. I calc 3 different hold out values in the FC-Edit software and copy them into the respective cells (I use 2000, 1000, and 500 msec as a start ...)

I have an area set up where I enter what I want the target A/F to be and calculate the new map values based on the inputs.

After entering all of the data I have charts set up so I can see what the curves look like to make sure there are no inconsistencies. I have the charts broken into groups of 5 MAP lines with one from the previous group for clarity...

This sheet doesn't tune the car for you, but I find it helps save me a lot of iterations and helps me keep the map smooth by using the charts... hope this makes sense and is useful...

Let me know if you have any questions/suggestions ... or just think I am an idiot

cewrx7r1

iTrader: (2)

Here is a simpler one from Barry Bordes which was posted here years ago.
It has three tables. Table one is where you paste your Map Watch AFR values.
Table two contains your AFR targets.
Table three is the fuel changes that you paste into the DATALOGIT Correction INJ Map.

blue87

iTrader: (2)

Yeah pretty much the same concept without the charts. I just realized that I posted the file that had data in it, meant to post the empty one originally...oh well.

Looking at the file you posted Cewrx7 I see that he has the AFR going to stoich all the way to 8000rpm in the vac areas. Do you have experience tuning / running this way, it seems to me that the engine would get a little toasty running stoich there? I know it may be different on every car and you need to monitor knock and maybe EGTs to see if it is a problem, but I was just curious as a general rule?

I am trying to tune my car as conservatively as possible at first and back off little by little as I get more rotary tuning expereience under my belt...

Thanks for the feedback!
Kevin

cewrx7r1

iTrader: (2)

So far I have only tuned cruise up to about 110mph because of lack of clear road usage. Takes a long distance to do high speed cruse testing.

Stoich is richer than the 15.5 - 16.5 AFRs that I run for most of my cruising.

BTU is the killer, not temperature.

blue87

iTrader: (2)

cewrx7r1, thanks for the reply.

So basically at high RPMs and low load (map) you are remainging lean/stoich without any troubles? So if you drove down the road at 30mph in 1st gear with no acceleration you are still lean, or do you go into enrichment in this area?

I have another question related to extremely lean cruise at say 16.5:1...

Do you get bad tip in shock when you accelerate since the accel injection compensation will bring you closer to LBT and you would get a resulting torque surge>?

Or do you have your tip in accel tuned well enough that the A/F ratio remains reltively constatnt?

cewrx7r1

iTrader: (2)

Q1: So basically at high RPMs and low load (map) you are remainging lean/stoich without any troubles?
A1: Yes

Q2: So if you drove down the road at 30mph in 1st gear with no acceleration you are still lean, or do you go into enrichment in this area?
A2: I run richer at lower rpms to preventbuckling due to my 8.5Lb flywheel. but at 30mph it is about 15AFR. 16-17AFR at cruise gives the best economy. Stoich is lease amount of bad gasses. 12.-12.5 is most power. Go reserach fuel AFRs on the net.

Q3: I have another question related to extremely lean cruise at say 16.5:1...
Do you get bad tip in shock when you accelerate since the accel injection compensation will bring you closer to LBT and you would get a resulting torque surge?
A3: good tip in but a little richer than stock.

Q4:Or do you have your tip in accel tuned well enough that the A/F ratio remains reltively constatnt?
A4: When you accel you want richer fuel, not lean fuel. Thus my AFRs go rich quickly. I tune for about 12.2 AFR from 0-4psi.
Tuning the PFC is a balancing act because some fuel cruise cells or also used for acceleration. Some cars have seperate map for cruise and acceleration/power.

But the change from vacuum to pressue in these engines is so fast that you need to go rich.

blue87

iTrader: (2)

Cewrx7r1,

Thanks for taking the time to answer some of my basic questions.

datum1-rx7

Very useful speadsheet -- will save this for reference