DFI Base Fuel Map ???????

[Butch]

I have transplanted a corvette LT1 into my full size Chevy truck and I am using the Accell DFI for Spark and Fuel control. It is running now but not very good. I don't know if it is rich or lean. The A/F Ratio from the O2 sensor shows between 12.7/1 and 14.7/1. It never go's above 14.7/1. I am guessing that it is running lean. The O2's are pretty low (Turbo Buick wise) 700ish on the full throttle blasts that I have made. I don't know if the O2's should be around 780 - 800 like with the Buicks or not?

I guess my question is regarding the DFI Base Fuel Map...
Is there any way to increase the entire fuel map buy say 10% all at once via CalMap? Or, do I have to adjust each cell individually?

I am kinda bummed because its running so badly. It kinda feels like it's running on 6 out of 8 cylinders. I pulled the #3 plug and it doesn't look good to me, but I don't know much about reading plugs.

Butch

 

[Reggie West]

Yes you can do that.
First boot CalMap and Edit ECM
The first thing you must do is go into Global controls and save the file you are currently using. This will allow you to edit the file. Name the file something easy you will recognize.
Once you do this Cal Map will take you back to the starting Menu

Use the Edit file option when you first boot up CalMap. Choose the edit file option. Calmap will default to a directory where all the files are. Type in the name of the file you just saved.

Select Base fuel map. This will bring map on the screen. Press the M key ( for multiply ) and box at the bottom will pop up. If you want to add 10% across the board type " 110 " in the box and hit Enter. The program will then re calibrate all of the cells with a 10% increase in each cell.

If you want to take out 10% you would type " 90 " and then hit Enter.

You can also add or subtract counts from the entire map. From the Base fuel map hit " A " to add and " S " for subtract. the little box will pop up again and you can enter how many counts you want to add or subtract from each cell.


As for the O2 readings it is not what you think. What that 02 graph is telling you is your base fuel map is rich. That graph is telling you how rich the Air/Fuel ratio would be if the ECM was using that value. DFI has a closed loop throttle option. What that does correct the A/F ratio to 14.7 until you go over a set percentage of the throttle.

Hope this helps

 

[Butch]

Reggie, WOW, Thanks for the great explanation! I will play with it some more in the next few days.

One more question...

How can I tell when the system is in closed/open loop? I think it is set to go into closed loop at 150 degrees (water temp).

Thanks,

Butch

 

[Reggie West]

Closed loop operation is controlled by how far you are in the throttle. That is what controls closed loop/open loop operation.

If you look on the Table called Configure ECM the setting can be found there. For getting started, I would set that at 50% throttle and leave it there. This will allow you good fuel economy in town and when you put your foot in it, the ECM will use whatever values you have in the table.

Good luck

 

[Reggie West]

One more thing. The only thing that is controlled by water temperature is the fuel enrichment. You can look at that graph in either mode. 9 times out of 10 I would leave it where its at.

 

[Butch]

Frustrated

Reggie, Well I did what you said and it works just as you said. Now my problem is that I can only find a way to import the complete ECU configuration file, not just the Base Fuel Map. So in the process of trying to copy the new file (10 minutes) with the fuel map adjustments the damn thing fails about half way through the process!@#$!@#.

Is there a way to just edit the Base Fuel Map and then copy just the BFM back into the ECU? If so I cannot figure it out.

I have looked through all of the manual.

Sorry to be such a PITA!

Butch

 

[Butch]

Something else that is weird...

When I am going down the road at say 45 mph my truck shifts into Overdrive (4L60E), then If I give just a little gas it starts knocking real bad. If I give it enough throttle to cause a down shift it runs fine.

This may be a tranny problem because I seem to remember it doing this with the other engine 3 years ago (the last time I drove it). I remember having to leave in 3 instead of Drive, around town. I also remember it not liking OD on the Hi-way below 70 mph.

I think maybe the Torque Convertor is locking up too early.

 

[Butch]

Reggie, I noticed in your other post, some concern about NGK spark plugs. I just thought I should mention that I am using NGK TR55's with V grove in this LT1 engine!

It's running better now that the #5 spark plug wire is not laying on the header

I did a compression test earlier today and all of the cylinders are at 180 +/- 5. The #5 plug was alot darker than the others, duh!

Here is that thread...
http://www.turbobuick.com/forums/showthread.php?s=&threadid=20644

Butch

 

[Reggie West]

Yeah Butch there is a way to edit just the base fuel map. You have to select the base fuel map just like you did the first time. Here is how. Go into edit ECM. Select base fuel map. This brings up three options. I think it is the last option that is Work with a fuel map from a file. I cant remember exactly how this works.

Check the manual. It is in there. Once you save just the base map in file, you can edit the file just like you did before. The difference is that you will have just changed only the fuel map. Then you can go back to Global controls and load up the new fuel map.

Hope that helps.

As for your plugs, I think the motor is fine. The plugs I pulled out were from a Stage 2 block that detonated on the #6 cylinder. This was with race gas, 26 psi and conservative timing. This was also the second time the motor has done this.

Here we were in Vegas for that event two weeks ago and we burn a piston on Friday night. It was a real pisser.

 

[Reggie West]

Butch the knocking problem in Overdrive is putting too much of a load on the motor at low rpm. That is normal with the stock ECM because the engineers burned the chip so the motor would handle it. You will have to look at where in the fuel map this is occurring and see if adding or subtracting fuel will help that.

If it is knocking, that may be a timing issue also. You can look at the ignition map while this is happening.

Once you find the cells where this is happening in the ignition map, you can play with them until it stops knocking. I dont know if increasing the timing ( this is my guess ) will help or not. Maybe some of the other guys on here will know better than I. You can mess with the cells while the car is running. Go the Base Ignition table and once the table is up type E for edit. From there you can change the value of any of the cells while the car is running. Once you are done, hit ESC and it will go back to its normal mode and the cell indicator will dance around the cell the ECM is currently using. That way you can see which cell you need to work on. Remember it is usuually not just on cell that needs to be changed, it is all of those around it that will smooth out the map.

I hope this has not confused you. Good luck

 

[Butch]

My problem is that it will not let me select just the Base Fuel Map for editing. I have to open a whole config file and then edit just the fuel map and then send that back to the ECU... which is when the problems start!

I'll look again.

thanks for all of your help.

Butch

 

[Butch]

OK, I have saved my base fuel map to a file and put it in the global/UNVRSL directory. Then I do Edit file and enter that file name... I get an Error #62.

Butch

PS. I cannot find anything in the manual.

 

[Reggie West]

There is a way to do just the base fuel map and then upload that map into the ECM. I dont have the laptop if front of me, it is with my Dad, he has two Buicks that runs DFI's in them. I am pretty much the one who tweaks them for him. My T type is still using a chip and stock ECM.

Let me know how it turns out.

 

[Reggie West]

Butch I dont have the book with me. Otherwise I would have my nose buried in it trying to help you with it.

Now its driving me nuts.

sorry.

 

[Butch]

ME 2.

Don't worry about it, I'll figure it out eventually.

Thanks again,

Butch

 

[Butch]

Heres another one for you...

With the FAST systems they are always talking about target A/F ratio around 11.0/1. How does that work when the computer is always trying to correct back to 14.7? Only when at full throttle I guess?

In other words, my system is always going to be 14.7/1 when in closed loop. What if that is not optimum? Or maybe it is.

I'm babling now

Butch

So like with my knocking problem when in Overdrive... Any changes I make to the Base Fuel Map will be ignored unless I am above the trigger point for open loop?

Make Sense?

 

[Reggie West]

The FAST systems are able to change the A/F ratio to whatever the user wants. You cant do that with a DFI. But you can change when the ECM goes in a open loop mode.

Configure ECM menu has a Closed Loop Throttle preset on it. That is where you can change where the ECM goes in open loop. As far as when it is in Overdrive, you will be at a very light throttle setting to begin with. So that means the only way to get the changes in the fuel map will be to set Closed Loop Throttle to 0%. That will make the ECM use whatever values you have in the cells ALL of the time.


14.7 to 1 is optimum for a gas motor. That is what the Society of Automotive Engineering came up with a long time ago. It is called Stoichiomety or in other words the correct air fuel ratio for a gasoline motor. You can go higher or lower with that ratio any time, and quite frankly the reason cars these days get such great gas milage at cruise and part throttle driving is the engineers lean them out a lot more than 14.7 to 1.


So in a nutshell what you are saying is dead on right.

 

[Butch]

So with the FAST system you can set your target AFR to whatever you want and the system will corect to that? That would be awesome, no wonder everyone uses that system. I am sure there are several other benefits to the FAST system.

Butch

 

[Reggie West]

Yeah you can do that and more. It is a pretty good system and I am hearing a lot of good things about them.

Really it depends on what you are trying to do with what you have . The DFI has been a good unit and it is a proven machine.

FAST is newer, it is a windows based software platform but ( of course ) it costs a lot more money. So as usual, if you got the money someone has what you want.

The DFI Gen 7 is out now. Ken Duttweiler likes it a lot. He has dynoed a couple of Buicks and even a 318 Dodge motor that is supposed to be in Car Craft soon on how easy it is to use but there again my Dad was looking at buying one for his Buick. By the time you added up all of the things you needed to make it work the price tag was $3000 bucks. So he decided to try the Variable Injector Controller with the batch fire box. That was another $700 just for that. As you can see the numbers add up quick.

How much and how fast is always the question.

 

[SingleTurboIroc]

just a quick add in here

i remember reading something that the 02 sensor voltage wont go over .800 in a DFI is that true?

so you have to figure out the a/f from that right?

.800 = what we are used to 1.00
and so on and so on

or am i mistaken?