6.0 to 4.8 Swap - Still super lean after fixing intake leaks

[Fast4.7]

10% probably about right with exhaust work and I’m sure the tune is still targeting 14.68 as stoich as well

I am thinking the same thing. Most fuel has 10% ethanol in it now. Thats like 7-8% lean right from the start.

[Ben Charles]

I am thinking the same thing. Most fuel has 10% ethanol in it now. Thats like 7-8% lean right from the start.

Yep… you would be surprised how many don’t take into account that…

[marmstrong]

I hadn't considered that at all. There's been ethanol in gas since before I started driving. So that really might be the last piece of the puzzle I'm looking for.

I have another MAF on my suburban that I can try out on the truck. If it works well on the truck and let's me get a good tune, I'll buy a new one for the suburban. I'll try to post an update later in the week.

So you typically shoot for a lower number for stoich because of the ethanol? Does that still work with stock narrow band O2 sensors?

[marmstrong]

Looked up the part about stoich. I'll probably keep it at 14.68 so if I do happen to get a "pure" batch it will be a little rich instead of lean. This thing will never see anything higher than 87 for what I'm doing with it. My suburban is going to require a little more care in the tuning, so I'm trying to pick up the good habits now.

[kevin87turbot]

Looked up the part about stoich. I'll probably keep it at 14.68 so if I do happen to get a "pure" batch it will be a little rich instead of lean. This thing will never see anything higher than 87 for what I'm doing with it. My suburban is going to require a little more care in the tuning, so I'm trying to pick up the good habits now.

14.108 is the number that OE's target on E10.

[blindsquirrel]

The 'standard' pump gas is about to go to 15%E, so more fun for everybody. Again.

[blindsquirrel]

For a MAF to read right its more than just the sensor itself, it's the wiring, and all the plumbing and any point where unmetered air could enter the engine, too.

[Ben Charles]

Last time I witnessed pure gas was about 15 years ago… so doubt Any out there, set stoich close to what you have available

[2xLS1]

Last time I witnessed pure gas was about 15 years ago… so doubt Any out there, set stoich close to what you have available

100% gas is available at just about every gas station in Okla City and most other cities in Okla. Most have 87, 89, and 91 octane 100% gas. E10 is available at those too usually only available as 87 octane. We just started getting some Casey's gas stations that sell what they call Super 88 octane that is E15. It is priced cheaper than E10 at those stations.

[blindsquirrel]

5% cheaper, and only cuts your fuel mileage by 10%. What a deal! BRB, gonna open a gas station...

[Ben Charles]

100% gas is available at just about every gas station in Okla City and most other cities in Okla. Most have 87, 89, and 91 octane 100% gas. E10 is available at those too usually only available as 87 octane. We just started getting some Casey's gas stations that sell what they call Super 88 octane that is E15. It is priced cheaper than E10 at those stations.

ANYTIME I’ve checked those or performed remote tunes with customer across the United States with ethanol sensors best I’ve witnessed was 3% most fall between 5-9%

But if Oklahoma has pure gas at 14.68, then good to know

[2xLS1]

ANYTIME I’ve checked those or performed remote tunes with customer across the United States with ethanol sensors best I’ve witnessed was 3% most fall between 5-9%

But if Oklahoma has pure gas at 14.68, then good to know

At least we have the option. You'd be surprised how many people here don't mind paying more and only use 100%. It's all I use. Wife's 13 Traverse gets 87 100%, my 13 GMC Sierra gets 89 100%. I tried both 87 E10 and 87 100% and it gets knock on those. I get 0 knock on the 89 100%. And i have 2 LS1 Camaros that get 91 100%. Also the 100% is great for all my lawn equipment. What's weird is usually E85 will be priced higher than E10 by 10-20 cents per gallon lately since gas prices have dropped. We have a just a few stations that have 93 100% but there is no 93 refined in Oklahoma since the Sinclair refinery in Tulsa quit making it probably 15 years ago. The few stations that do have 93 like VP Fuels get it trucked in from other states. We even have a few stations that have 100 octane 100% unleaded at the pump.

[Paulster2]

... What's weird is usually E85 will be priced higher than E10 by 10-20 cents per gallon lately since gas prices have dropped ....

Gas prices dropped? When did that happen?

[2xLS1]

Gas prices dropped? When did that happen?

In June E10 prices were over $4/gal here. In December they got as low as $2.39. They are currently in the $2.8x range. So yes gas prices have dropped from their highs. 100% 87 octane is typically .40/gal higher than E10. Add another .30 for 89 and .60 for 91 100%. That is for top tier gas.

[marmstrong]

Great info on ethanol content here. I'll throw in that some simple mixtures math tells you that even if you run the tank down to 15% capacity with E10, then fill up with 100% gasoline, you're still going to have a small percentage (<1% in this case) of ethanol. If you're kind to your fuel pump and fill up more often, you'll have even more 'residual' ethanol in the tank.


So, back to my tuning issues. I swapped the MAF from my suburban project into the truck and did another once-over on the intake tract. Everything looks good. Here's the new log and that spreadsheet I forgot to include before.

Silverado Tune Mods.xlsx
2023.01.17 - suburban MAF, baseline tune.hpl


The STFT+LTFT table shows a gradual increase in fuel trims with MAP and RPM. I did sporadically get a P0300 misfire code, especially around 2800rpm, 40kPa. I'm assuming that's mostly from the fuel trims sorting themselves out, but it probably wouldn't hurt to replace the plugs.

Based on the info here I probably will drop stoich down to 14.1 or so. This thing will never see 'good' gas. At least I can plan for it when I'm doing the tune.

All the helped has been greatly appreciated!

[Fast4.7]

5% cheaper, and only cuts your fuel mileage by 10%. What a deal! BRB, gonna open a gas station...

5% Ethanol is not changing your mileage enough to notice. I have run it. See very little difference between Non-Ethanol and E15. Running E85 which was more like E70 when I checked, I lost a whole 2 mpg average. From 16 to 14. I still got 18 mpg on a long trip on E85 with a 500 hp V8 in a 6,500 lbs brick.

Just yesterday at the pump. E10 87 was $2.99/gal, E10 91 was $3.79/gal and E85 was $2.19/gal. It is cheaper to run my engines on E85 than it is to run on 87 much less the 91+ my 383 requires.