Richer EFI Chip

[Dean Dorsey]

Is there a digital chip for the 2.5 260 that is non potted uses a 39 regulator, and is richer than the A-48 on the top end? I am at 1300+ degrees by 6800 rpm with my A-48 and would like to avoid a 56 regulator if possible. Thanks, Dean

[RichS]

Try running over 7K. The drag boxes are REAL LEAN from 4500-5500 to 7K. I run my stuff real rich and I still can't keep a steady throttle in that range. The egt starts climbing and doesn't stop until I punch it over 7 or ease off. Over 7K things cool down.

[Dean Dorsey]

Thanks Rich, I had heard the same thing about the drag chips, but I thought the lean spot was between 5-6K and that the A48 was exempt from that lean probem. Maybe I need a customized chip, my hull is very heavy I don't think I will be able to turn the motor much beyond about 7,000 rpm with this hull and by the time I get there the motor will be toast with the current chip. Your help is appreciated. Dean

[dennymac]

dean, even though you don't need it...i'm assuming you run pump gas heads...mix a little race fuel, say, i gallon race to 4 gallons pump, and i guarantee your pyro's will drop...dmac

[RichS]

I didn't realize that this was on a BIG BOAT:eek: You would be better off with a A-49 chip. The A-48 is a full race ONLY chip. It isn't designed to be an all around/cruiser fuel curve.

[Dean Dorsey]

Thanks guys, Great suggestions dmac I had considered doing this but my compression is between 134-140 I do have one bore at 146, thought I would not help, will give this a try. Rich the boat is a 20ft. Awesome Cat true tunnel, by looking at it you would think it was light, but it weighs 1800 lbs. before you hang a motor on it. I will look carefully at the A-49 chip as well. Last stupid question, which way do you turn the adjustment dial to enrichen the overall mix. I have always had CDI non adjustabe boxes, and have one merc digital I would like to work with, at least until I can be assured I have a handle on the heat problem. Thanks, Dean

[RichS]

You would have to ask that:( My stuff is all apart and I don't turn that thing enough to remember.....

[WaterBoy]

If I'm thinking correct, Clockwise= richer, and Counterclockwise=leaner.

BUT, I WOULDN'T MESS WITH THE THROTTLE POSITION SENSOR WITHOUT SOMETHING TO CHECK IT WITH, LIKE A DDT OR SOMETHING SIMULAR. You accidently turn it the wrong way too much= rebuild time

Waterboy

[Dean Dorsey]

Waterboy, You are correct John Marles straighten me out today clockwise is richer counter for leaner. I would not normally adjust it W/O a DDT but I sold mine, so I will have to do it in extremely small increments using my EGTs. If can't get much leaner I am already at 1250 degrees at 6,200 and almost cooked at 6,800 at 1,350 degrees I am only going one way richer. On a digital ECU the enrichener access hole and slotted plastic screw is for overall enrichment or leanout isn't it? I don't think it has an effect on the overall map curve. Thanks again guys. Dean

[dennymac]

don't even think about adjusting the screw on the merc digital box without something to read it...you can't imagine how small of an adjustment it takes to change the number...if you do determine that the a-48 is too lean in the middle, you can have a custom chip built for that box that is fatter in the middle/top...several people on this board burn them to whatever you want...i've got several...cost about $100 to $120, depends on who does it...it's an e-prom, just plugs in...no problem...try a little race fuel in the interim, i think you will be surprised...dmac

[Dean Dorsey]

dmac, Now you got me really regreting selling my chopper city tester. The box is already set at full rich, it came to me with a 2 Ltr. A-45 chip in it that was controlling this2.5 260 in a stock form before the re-build. I will change to the A-48 chip and leave it full rich. If I need to lean I will use my dash pot to try to accomplish it. I will use the race fuel idea if needed. Do you have a good A-48 chip richened in the middle you want to sell? If not I will give Sean a call. Thanks, Dean