I have a '68 Camaro with a fresh 454; aluminum heads, roller cam, etc, etc. The most interesting part of the setup is the Accel Gen 7 DFI (digital fuel injection). I am trying to tune with the laptop and it gets kinda confusing sometimes. There are LOTS of screens with an infinite number of combinations.

The car actually runs fairly well using a baseline 454 map that came with the software, but of course, I still need fine tuning.

The instruction manual that comes with the DFI isn't very good, IMO, and I'm trying to find something better. Does anyone know of any well-written basic instructions for tuning the Accel DFI??

thanks

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"Does anyone know of any well-written basic instructions for tuning the Accel DFI??"

thats the problem with the gen7, there really is no support or general instructions for it...fast,megasquirt and others have awesome support, and have complete formums dedicated to them..i have gen7 on my 67(383), you pretty much have to learn on your own...what do you want to know???maybe i can help you out...do you have the wideband option??that makes it alot easier to tune the fuel map...are you running a knock sensor??anyway let me know if i can help, i will do my best to answer any questions you have..also check out these links the have some pretty smart guys on this subject...
mike
http://thirdgen.org/techbb2/forumdisplay.php?s=&forumid=37
http://www.turbobuick.com/forums/forumdisplay.php?f=13

You might try downloading Holley's tuning manual for their injection. It's a pretty well written thing, and I'm sure the basic fuel map functions are the same on most any spped-density system.
What I've done is lock it in closed loop, and use the o2 comp value as an air/fuel guage... if it's adding fuel, then you're lean, if it's taking it out, then you're rich.

yeah jim is right, i forgot about that manuel...i looked at it and its pretty good,its all basically the same when tuning a FI engine...i don't see why accel can't make something like that...its almost like they want to keep it a big secret...if i had to do it again i would't buy the accel setup, not because its no good or anything but just because their tech support is horrible...
mike

emt and Jim, thanks for the replies. I've actually had the setup for two years, but had a couple of guys tune it for a different engine. I got a fresh angine and I'm gonna try to tune it myself this time. I have contacted Accel tech support a few times and they always got back to me, but I haven't been able to find some sort of simple manual.

I'm using the wide-band O2 sensor. As far as I understand you make most changes in the VE table, is that correct? How do you know what to adjust it to? Do you do it by feel as driving along or do you watch the A/F ratio and adjust to that?

I really should learn the "data log" feature, so I can drive around and then analyze the results when safely stopped. It's real tricky to drive and watch the computer at the same time, LOL. Any tips on using data logging?

thanks a bunch

emt, I looked at those links you provided. Not much there specific to the Accel. If I post DFI questions on those forums, would guys answer? Do you know of any forums for the Accel?

I really can't believe I'm having such a hard time finding basic info. It's like you better already be a EFI expert tuner, or else you're s**t out of luck.

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What I did in the past was to "run the car on the MAP", that is accellerate thru the entire rpm range while holding the MAP output to a specific value (even if it required using the brakes!) While accellerating at a given MAP output, I would log the o2 comp value every 500 rpm or so, then change the ve table for that MAP value as needed to get the O2 comp as close to zero as possible.

then repeat the test at maybe 2 or 3 in/hg different MAP value, etc etc.

Then put the fuel map display in "graph mode" and kinda woirk it till it looked "smooth"

Important to do all the testing at operating temp and "typical" air temperature."

Once the main table is right, it's pretty easy to work out the "power enrichment" table, temp comp should be pretty close out of the box.

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What I've done is lock it in closed loop, and use the o2 comp value as an air/fuel guage... if it's adding fuel, then you're lean, if it's taking it out, then you're rich.

Yeah, I've been watching and seeing it runs lean, as wide-band is adding quite a bit (15 to 20) at most rpm's. But my question is; what's the sensor basing rich or lean on? The VE or the A/F tables?

thanks

basically what your trying to accomplish is to match the actual a:f ratio to your target a:f table...so if for example your actual a:f ratio is say 14.0:1 and in your target a:f ratio table says 14.5:1 then you will see the o2 sensor correcting it that half of point....now what you do is look at the o2 correction and see how much its taking out(in this case)and then go to the base ve map,and take out the percentage in that cell(and surrounding cells)...this is where math comes in to play...say your base ve says .450 and the o2 correction is .900,then you would need to remove 10% in that cell...so you would change the .450 to .405.....you also need to change the surrounding cells because you want a smooth transition from one cell to another...

The o2 correction is a decimal number or multiplier co-efficient. if it says .85 it is removing 15% fuel 1.10 it would be adding 10% fuel. You must look at the a/f and o2 correction during wot operation, preferable in 3rd gear, not after a shift, not de-acceleration or acceleratiing. Log the rpm,map, a/f,o2 correction, maybe knock and pw or duty cycle.
Overlay your log to your ve map and remeber the data point numbers that you got smooth data (ie 3rd gear pull) Correct a few percent only at a time . Do another pass over wise you can overcorrect as there is some lag to the o2 correction and will slighty throw you off. What is your a/f fuel ratio at wot?
mike

the sensor if based on "REALITY" if there is oxygen in the exhaust, the o2 comp will add fuel, then the base table is lean.

Unfortunately, I'm not familiar with what Accel "calls" thier tables, so my terminology may be wrong.

On a holley system there is a "base fuel map"
a "power enrichment map" which only applies when the throttle is moved suddenly, and then only applys briefly, like an accelerator pump on a carb.
and auxiliary maps for coolant and air temperature.

basically what your trying to accomplish is to match the actual a:f ratio to your target a:f table........

Are you just making the assumption that the Calmap-supplied target A/F table is 100% correct? Or would there be instances where you would actually need to adjust the target A/F table at some point?

thanks

forgot to mention that the target a:f ratio table must be where you want it otherwise everything will be off because this table is what the o2 sensor is basing everythig from.....
mike

yes there are instances where you would need to adjust it....take a look at your spark plugs at idle (for instance)see how they look...is that a good
a:f ratio???i would run an a:f ratio of 12-12.5:1 at wot...you kinda have to play with it(safely)and see what your motor likes...14.7:1 is really a generic #,your motor might like to idle at say 15.0:1...thats where mine seems happy for example....

are u using one of the maps that came with calmap???if so give me the file name and i will look at it on mine and see what you have..
mike

The Gen VII is a toughie to tune compared to others. It has a lot of things going on in the background that you don't know about. For example you can shut off the O2 in the tune and the computer is still adjusting things based on the shut off O2. The TAU map they use for acceleration enrichment is silly compared to a simple enrichment map Holley, FAST, etc. use.

With all that said you need to get your a/f table set correctly first. Then with the wideband and closed loop make corrections to your base ve table as explained above. If it's adding 6% then you change the base numbers 6% and blend the surrounding areas. One thing that really helps with smoothing is the 3D maps they have. Open the 3D base fuel map and it will show if things are blended well; spikes will show up as sharp peaks or valleys. Otherwise it should look fairly smooth with a low elevation at idle and cruise areas smoothing climbing to a plateau at the wot areas.

You'll never get it perfect with no correcting under closed loop, but if it stays within a few % you're fine.

The other thing I don't like about that system is the two keys they use for tuning; sportsmen and pro I think they call them. The regular people get the sportsmen key which only allows access to some of the tuning maps. The pro key is for the tuners. I see why they do it to an extent as some of the pro features would get a beginner in trouble. Problem is, I've needed the pro key to tune on every one as there were settings that needed to be changed that the standard key couldn't get to.

As far as datalogging, you either need to do that (call them to find out how or what is needed) or have a friend drive your car around while you tune on the laptop.

Jody

jody, i agree that its silly...thats another reason that if i had to do it over again i would go with either hooley or fast...
mike