Injector offset FV question

b18apwr · Post by **b18apwr** » Wed Nov 18, 2009 4:00 pm

So, I don't want to sound like a total idiot, but I'm having some issues with setting FV. A little information first: b18a Crane #12 cams AEM cam gears (0, 0 for now) Skunk2 Pro IM 70mm Blox throttle body AEM intake Hytech header HKS sport exhaust stock 240cc OBD0 injectors (these aren't in the injector selection tables) B&M FPR set to stock pressure LC-1 using serial stream for datalogging in eCtune I've been using eCtune Pro since April of '08, so I feel like a real noob asking this. If I create a basemap for my setup, I use the P28 USDM ecu and then select the P75-274 (LS)stock maps. If I start my car without changing anything, I get a warm idle at about 12.6 afr. Everything I have read says I need to adjust FV until I get the right idle. Everything I do with FV just seems to make it more rich. I know FV doesn't support a negative value, so should I be using a negative overall fuel trim value to get my idle right? I can easily lean the maps out around my idle cells and correct my idle, but this doesn't seem to be the way I should be going about this. I'm going to attach my current .cal. This has my battery offset tuned and my idle around 14.5 via cell adjustment. The car runs really on this tune, but I feel like I'm not being as thorough as I should be. I'd like to start ignition tuning, but I want to make sure that my fuel tuning is done correctly before I move on. Thanks in advance.

Post by **Gaskleppie** » Thu Nov 19, 2009 2:09 am

FV cant be negative as far as I know. So when you are still too rich (have you raise your fuel pressure?) just lower the values in the low cam map around idle.

TopMountGSR · Post by **TopMountGSR** » Thu Nov 19, 2009 7:24 am

Its nice to see someone from KY using ectune, I am local, if you ever need anything please feel free to pm, txt, or call me. Ditch that fpr, they are a tuning nightmare as they can fluctuate. I would just use a stock fpr as most of the time that's all that is needed. I normally start with my imported tables that are smooth as glass, how smooth the car runs reflects this. Then use the overall trim to get a close air fuel at idle and raise and lower each row as needed while I'm driving to hit target afrs in different loads, then modify the fuel curves in the tables as needed. Also don't be afraid to run the 1st two columns a little rich, most cars like this and it makes the off and on transition of the throttle as smooth as glass. Sometimes you have to ignore the overlayed air fuel data in these columns. Give the car what it wants, I run my cars partials a bit richer than most, it loves it, produces more power, a lot smoother and gas mileage doesn't seem to be affected as much as you would think. Also if you are sticking with NA, I would use high res fuel and ignition tables. Its fun tuning one with them and its rewarding seeing how well they run in the end. Here is a picture of my fuel map, vs your fuel map, see the difference? You want smooth rows that hit a target air fuel safe range, not an exact target number for every cell, that leads to rough maps.

Hope this helps,

b18apwr · Post by **b18apwr** » Thu Nov 19, 2009 3:41 pm

TopMount, I've always lurked on here and saw you were in Frankfort. I'd love to pick your brain sometime about all this. You stated you tune row at a time. So, you take the pressure ranged for a given RPM and make an adjustment to the entire selection? I understand how that would make your range smoother. I guess I need to reevaluate how I'm doing all this. I currently only tune in 4th gear. I don't log data from any other gear. Either way, I've decided to start from scratch. As of my typing this, I've taken a stock LS map and have converted it to a 20 column map. I'm going to start over, get my idle right using injector trim, then set my battery offsets, and then try to work out a smoother map. Does this sound like the best approach?

TopMountGSR · Post by **TopMountGSR** » Sat Nov 21, 2009 5:47 am

b18apwr wrote:TopMount, I've always lurked on here and saw you were in Frankfort. I'd love to pick your brain sometime about all this.

Hey man feel free to contact me anytime, I offer my learning curve for free to anyone willing to listen.

You stated you tune row at a time. So, you take the pressure ranged for a given RPM and make an adjustment to the entire selection?

I may have mis spoken, I adjust the entire column at once; column if you are looking at the fuel tables, row if you are looking at it in 2d/3d. I adjust across the entire rpm range vs one pressure. I normally grab columns 1-3 dial in idle, then individually grab 4, adjust it, move to 5, adjust it, etc.. then later on manipulate the fuel curves only as needed. I rarely have to do much to any curves when I start with my imported tables, depending on the size of the turbo normally decides how much fueling it wants in its fuel curve up top or cam profile for na cars. Start everything rich, I normally roughly get all of my partials to 13.5~ish and lean them from there, but not much. I used to tune partials @ ~16 afrs, now I think that's stupid and not worth the power and response loss for the marginal mpg gains from a 14.0-14.5 afr range. I've actually tuned two maps of each, put them on a switch, and hit it driving down the interstate, when you goto the leaner map, its like someone latched a trailer on the back of your car, bogs it back and requires more TPS % to go the same speed. Also, if you create an un needed fuel curve hump, below and above will be greatly effected creating a valley in the surrounding lines because there is so much fuel added in its neighbor. This is an easy way to tell whats right and wrong fuel curve wise; get used to the interpolate buttons, when you learn how to use them as they save loads of time. I like the 'interpolate column' button. Here is an example of how to use it, create a nice fuel curve for all 1 psi cells, then nice fuel curve for 40psi's cells, highlight 1-40psi, then interpolate column button, and bam; everything matches and is spaced evenly, all columns, 1-40psi.

I currently only tune in 4th gear. I don't log data from any other gear.

That's great! I tune in 3rd gear to prevent 140+mph pulls I use the gear fuel trims to add fuel 1st and 2nd, and subtract in 4th and 5th. I normally add 6-8% in 1st/2nd and subtract 2-3% in 4th and 5th. 6-8% in 1st and 2nd is a bit much and not really needed but its so nice as it smooths those two gears out so much, it deletes all hiccups in parking lots, slow cruises, etc.. On off transition of the throttle is like butter and I see safe afrs in 1st and 2nd at the track under load at 18+psi, according to my logs. I add more fuel in 1st than I do second, but just remove 2% out of 4th and 2-3% out of 5th depending on how rich you like it to cruise at in 5th. I like 2%, little richer, a lot smoother. Honestly, my partial air fuels in 1st/2nd are in the 12s.. Sounds pretty wack but works beautifully.

TopMountGSR · Post by **TopMountGSR** » Sat Nov 21, 2009 5:51 am

Part 2:

Either way, I've decided to start from scratch. As of my typing this, I've taken a stock LS map and have converted it to a 20 column map. I'm going to start over, get my idle right using injector trim, then set my battery offsets, and then try to work out a smoother map. Does this sound like the best approach?

Yes 100%, its funny, when I started with ectune, it'd run so smooth right off the bat, then I'd tune it for weeks and just wind up with a rough graph and a rough running car. Get used to tuning it from scratch, just makes you better in the end. I bet I have 10+ maps for one season for one car that I spend time with. Save copys, try this, try that, etc. Battery offset tuning is a must, use one of Bugermass's excellent methods, just unplug the big alternator plug while its running; then match the air fuels in from ~14v to now ~12v, then interpolate everything in between and 2d rich guess everything lower than 12v. There might still be a little fine tuning, loading the electrical system down, adjusting and so forth. The 2d button is an excellent tool, use this whenever adjusting anything that has this working button. Make everything as smooth as possible. If you will take the time to try one of my hi res fuel maps, I'll send you one, it would be an excellent start using my column adj method. Hope this helps, DK

IntegraVTEC · Post by **IntegraVTEC** » Wed Nov 25, 2009 8:36 pm

Smooth = smooth running car!!! I see you are still using that technique DK!! Works great. Another way to reduce bucking at very light throttle in lower gears is to pull some ignition timing in those areas of the ignition map. That also works like a charm. Basically you are reducing the power at that rpm/load point. And that can be done by richening the fuel and \"drowning\" it to where it reduces power or also by pulling timing to reduce engine power. Just something you guy's may look at as well.

Post by **Bugermass** » Wed Nov 25, 2009 11:00 pm

one thing that no one pointed out, are you letting the car wamr up completely before trying to adjust things? During initial startup and warmup the ECT table adds quite a bit of fuel and will make the car run rich until it warms up.. if your cold start puts you around 12.6 then your running temps will probably net you in the high 13s mabey even the 14s.. Make sure your at operating temp before trying to dial in fueling.. Also I usualy cut all the ECT values in half. Our manifolds don't seem to be very prone to puddling.