using 14.047 for desired AFR and not 14.63?

[Chalky]

Not sure why your LT keep adding fuel unless youa re seeing more ethanol or just better air/temps. All things being equal, your LT should get close to "0" by themselves. Your ST and LT trims adjustments are basically tweaking fuel delivery to keep your afr at stoich.

If you change B3601 to 14.16, 14.16 becomes your stoich. EFILive will then make changes to your OLCF table and your PE tables reflecting changes to B3601.

Much is dependent on what your currently have B3601 currently set at using your 91 fuel. If your B3601 is set to say, 14.63 and your change B3601 to 14.16, your PE table will change as well. I will assume your current B3601 is 14.63 and your PE table is flatlined at 12.3. If you change B3601 to 14.16, your PE table will be revised to approx 11.7:1 from 12.3:1. 11.7:1 is rich for even e10.

Try it. Create a dummy tune file of a current file. Change B3601 to 14.16. Save it. Open file back up and look at look at PE table. You will have new values.

My suggestion, find out what ethanol content is in your area. I bought a test kit used by airplane owners. I get mine from EAA in Oshkosh, WI. In SE WI, our E10 is really E5 for the summer blend.

Not sure about all WB's as far as readings. I believe Innovative LC1/etc c an be programmed to reflect revised stoich.

As far as E85, your could adjust B3601 to reflect stoich for E85 9.85. You would be in the ballpark. Question would be, are injectors and fuel system able to meet demand?

[picnic_george]

We have e10 oct 31 til jan 31??? here. It's considerably less during the other months. So my fuel trims being positive have nothing to do with running a fuel that commands more fuel to reach stoichiometry?
As far as air temps go, I live in the high desert. It can be 90 or snowing on the same day.

[Chalky]

Your LTFT should get back to close to "0" all things being equal. The problem is what could cause the engine to want to add fuel. Cooler temps, lower humidity, slightly different blends of ethanol, whatever. Have you tried resetting LTFT and see what happens?

If you were to start out in the morning with cool temps and a nice dense air charge, I could see the 02's commanding more fuel. If you continued driving and the temps went from say 30* to 90* and humidity jumped, your 02's would normally start pulling fuel to lean car out to maintain stoich. There are a number of influences to ltft adjustments than just fuel type.

As far as fuels, e10 will cause your 02s to add fuel to return car to stoich of 14.63 or whatever your B3601 is set at. Over time, your LTFTs will make adjustments to work with the e10 up to a point. While e10 will cause your 02's to command more fuel for a period of time, it should balance out eventually. They will never be "0" though.

Try this, assuming B3601 is currently B3601, change this tables to 14.10, load the file to your ecm. Start up scantool and log stft and ltft. Chances are very good, stft/ltft will pull fuel.

lastly, just because your pumps show e10 stickers, the actual fuel may in fact , be considerable less than 10% ethanol.

[picnic_george]

Ok so I reset my fuel trims and immediately they went positive and stayed there. Do you presume I just need to retune the car?
On the flip side I set b3601 to 14.17 and my commanded matched my actual afr idle average and in pe. I guess that's good lol. I need to tune my car at sea level I think because I'm sure if they are positive here at 4500ft they'll be way positive there which probably isn't a good thing. Unless I'm thinking backwards and positive fuel trim is pulling fuel not adding it.

[Chalky]

Have you changed intake systems or had your intake apart? You may have a persistent air leak. ?Can't believe a tune would help..

Any mods? Can you attach a log from scantool showing stft and ltft? Include a copy of the tune as well.

Positive trims mean fuel being added. FWIW, Not sure how big a positive reading you are getting but a couple of percentage points isn't a big deal.
.

[picnic_george]

I'll post my tune and log when I get home. I just logged a 10 min drive to my friends house. Seems to be about +10. I don't think there is a vacuum leak the maf is reading 10gs/sec which it has always seen at idle. I think my fuel trims may have always be positive though.

[picnic_george]

But here is what it is right now. I just added a few degrees of timing to see if I could pick some hp on the butt dyno. First log is driving to a friends house the other one was a quick little blip to check my afrs. I'm not real happy with the tune on this car anyways so I'm going to redo it. I think I may know why my fuel trims are off.
This car is a 98 trans am(98 pcm) m6 forged 347 ls6, 228/232 112 11-11.5:1 cr 100 octane pump gas.

[Chalky]

Quick solution: With a cam in that range, your 02's will pretty much think the car is always lean due to 02 sensors seeing unburnt fuel. That is the reason you are seeing positive fuel trims. I would guess that the car acts and reads quite lean at idle.

I ran a 224/228 on a 114 and had same issue.

After a quick look:

MAF table is rough. MAF table is normally a smooth transition from low to high.
VE Tables: Again, really rough with spikes. I would expect a more rounded graph in the 4800 rpm range. Also seems like lower rpm, idle range is very lean.

IFR table: Not sure what injectors you are running but the IFR table values have almost doubled over stock.

What type of injectors are you using?
What intake manifold are you using, LS1, LS6, FAST?
Stock TB?




Spark tables: Changes made to date are pretty much ineffective.

I ran a very similar setup with 11.5:1 CR.

[picnic_george]

Crazy elevation (7200-0ft) and weather changes. I'm keeping the o2 sensors, I need all the correction I can get lol

[CalEditor]

I posted some information that wasn't so good.
Set you stoich to 14.0 if you have E10

I would think if you have E10 then you will be on the High Octane Table








2002 MPV 5.3L L59 Flex Fuel K1500 12216125.bin.zip