In this part of the USA E-10 seems to be what all the gas stations are serving these days. Being that this fuel is 10% alcohol and 90% gasoline it has a stoichiometric ratio of 14.3:1 as opposed to 14.7:1 for straight gasoline. DOes anyone know if we set the base stoich to 14.3 will this help enrich all values in the fueling tables? Is it beneficial or will this mess up the
O2 sensor readings?
Very beneficial! Have a look at these:
http://www.hptuners.com/forum/showthread.php?t=17154
http://www.hptuners.com/forum/showthread.php?p=165626
http://www.hptuners.com/forum/showthread.php?t=22448
Pay attention to what eficalibrator and RWTD advise, they both tune professionally.
I drive E10 in Michigan. I took a stock tune and made only two changes Stoich AFR to 14.13:1 and PE Base AFR to 11.3:1 (11.7 for the SC L67 and About -.4 to -.5 for E10. My 3-5 degrees of "mystery KR" disappeared and my trims got a LOT closer to zero. From there MAF tuning was a breeze as were several of the other write-ups.
As passingpower said, definitely adjust the stoich value, as that will adjust ALL fueling parameters in accordance. Also, E10 is approx. 14.1, not 14.3.
Formerly known as RWTD
Toys: '22 Tesla Model S Plaid / '20 Chevy Duramax / ?20 Sea-Doo RXT-X (2)
Ok so I browsed through those links but didn't see what I was looking for.
Would it be better to adjust your stoich value at the beginning of your tune, or tune for 14.7, then go back and fine tune for the 14.1?
Start with a stock tune.
Set stoich to 14.13:1. (E-10)
Set PE Base AFR to 11.3 or 11.2 if your forced induction, 11.9 or 12.0 for NA.
That's it!
Now marvel at how the powertrain responds to further tuning the way you expect it to.
The problem here in VA is that we have E10 in the metro areas, but when I travel all gas is the norm.
I've thought about going "midway" with 14.4 because of this.
Any thoughts on that?
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Good engineering is simply finding the right wrench to pound in the correct screw.
Going "midway" is also called "splitting the difference". At 14.4:1 its the best option when you can't predict or tune for what you're filling up with.
The down side is that your trims will always be a little off but, not as far as if you're tuned for the opposite fuel.
Given the level of "difficulty" in making changes in two values and cal flashing, I'd suggest you fill up with either E-0 petrol or E-10 gasahol for tuning purposes.
Set your AFRs for that fuel, and complete tour tune.
After you get tuned, then go midway and split the difference. Then, just accept that your trims will be off but, not by much.
I feel that splitting the difference is the best option because I also live in Michigan and the keywords on the pump are "may contain up to 10% ethanol" which who in the hell knows if it is 3%, 6%, 10%, 2% from station to station.Originally Posted by passingpower
2017 Silverado LTZ
According to the Energy Independence and Security Act of 2007, There isn't even a requirement that pumps be labeled that they contain ANY ethanol, much less the exact ammount. I have personally not seen a label on a pump in West Mich. for several years. The only way I know it's E-10 is this:
http://www.fhwa.dot.gov/policy/ohim/hs04/htm/mf33e.htm
Hmm interesting. I live down by the St. Joe/ Benton Harbor area and work down by Notre Dame and the majority of the pumps around here and by my house state that right on the pumps about "may contain up to 10% ethanol"
2017 Silverado LTZ
We seemed to have gotten around the E-10 isue by setting the stoich to 14.4 and lowering the Base PE numbers to around 12. Additional fueling is provided by lowering the values in the PE vs RPM vs Time adder table. KR's now seem more under control with only 1-2 degrees in a few areas.
We did not set the base stoich at 14.1 because some of the pumps around here say May Contain up to 10% Ethanol. So it doesn't seem cut and dry about how much alcohol you are buying.
Are you referring the adjusting the PE mulitplier by RPM to reflect a new richer commanded WOT AFR?
For example to run a PE AFR of 11.3 with a 14.4 stoich setting, you set all the cells in the PE muliplier table to 1.274? 14.4/1.274= ~11.3 Right?
I am trying to tune a supercharged Cobalt SS/SC for E10 and just wanted to verify this information. Our normal 'safe' AFR at WOT is ~11.8 Does running the E10 make the new 'safe' AFT at WOT at ~11.3? Or am I still shooting for the leaner AFR of ~11.8? I am uncertain on this one as I have read of some people only changing the stoich value, and have heard of others changing stoich and PE fueling. I believe the PE fueling should be changed also, but I'm not sure to which value on my boosted application for safety and power?
I don't believe that any tuning needs to be done. Switching from straight 93 to say 93 with 10% ethanol, if that did indeed lean it out and contain higher anti knock properties... We'd see a power increase. no?
Can anybody else give some insight? I set my E10 tune stoich to ~14.4 and set my PE enrich values to 1.274 to command ~11.3 at WOT. I haven't had time to do much logging, but my KR especially during throttle tip-in has improved (on my LSJ).
Running more timing and working on the tune with ethanol is what will add to a power increase.
I just need some clarification as to what the proper stoich and PE AFR should be. I doubt I could blow the motor as I'm now running richer, but I'm not sure if what I've done is 'right', or if I'm just seeing less KR due to the extra fuel cooling things down a bit. The car feels fine, but I'm not 100% certain on this...
Yes if you are running e10 then just a simple change of stoich is the ONLY thing that needs to be done in the tune as long as your ve and or maf tables were tuned right in the first place. Leave your PE rate the same as well.
Stoich for e10 is 14.13 and if you arent sure if it is quite 10% ethanol then you can use 14.3-14.4 to split the difference between 0% and 10%. Me personally I didnt want to guess so I got real technical and purchased an ethanol test kit for about $30 so I could see the exact percentages of ethanol from my local gas stations. Most of them were right around 5%-7% so I have set my stoich value to 14.3
2017 Silverado LTZ
Klug, thanks for the responce!
So... You said changing stoich was the ONLY thing to do? What about PE? With a different stoich value, the PE scalar now commands a different PE WOT value.
Here is what you suggested with changing the stoich value only.
Gas: 14.7 stoich / 1.245 PE = 11.8 WOT AFR
E10: 14.4 stoich / 1.245 PE = 11.5 WOT AFR
Now I was under the understanding that the proper WOT AFR for boosted E10 should be about 11.3 AFR. That would mean the PE multiplier needs changed to 1.274 as below.
E10: 14.4 stocih / 1.274 PE = 11.3 WOT AFR
Which is right? I can't find a clear answer on this.
Last edited by csementuh; 12-13-2009 at 09:38 PM.
Stoich should be one of the first things to calibrate in your pre-tune setup. Be sure you know your ethanol content and be mechanically sound. (If you're fussy about your tune, you may consider a new fuel filter and reCALIBRATING your IFR table. When I say that, I'm not telling you to doink around with it in the manner found in all-too-many write ups. Use the Fuel Injector Calculator in VCM Editor and the spec pump pressure and inj flow rate. It's a fair ammount of work so, only if you're anal about your tune.)
Stoich AFR defines the closed loop fuel mixture.
PE Base AFR vs. ECT defines open loop fuel mixture.
The scalars adjust the above PE Base AFR value.
Using an example of E-10:
Set stoich to 14.13:1. (E-10)
Set PE Base AFR (above 50˚F ECT) to 11.3 or 11.2 if your forced induction, 11.9 or 12.0 for NA. (The name of the table is "PE Base AFR vs. ECT")
AS A STARTING POINT you should not need to change your scalars. that would only change the RATE at which enrichment takes place. As you get deeper into WOT tuning, I recommend CCB's VROOOM table for PE Add vs. RPM. Refer to The Open Tuner Notebook for that one.
Last edited by passingpower; 12-14-2009 at 07:49 AM. Reason: clarity
Before I get too specific. Some basics. What are you tuning?
Yr, model, engine and mods.
Thanks for the response!
I drive a 2007 Cobalt SS/SC 2.0 LSJ
My performance mods are...
2.7" pulley, lightly ported M62 and LSJ TB with OTTP spacer (have a LS4 TB that I used to run also), Siemens 60#/hr Injectors, RAW 3" CAI w/ AEM Dryflow, Dual Pass w/ Option B, ZZP S3 H/E, Clear Image Auto Header, 3" downpipe, 3" Mandrel Catback w/ resonator and Magnaflow muffler, NGK BKR7E Spark Plugs.
I do not seem to have this 'PE Base AFR vs. ECT' table in my tune file? I have always seen the stoich set under Engine->Fuel Control->General->Stoich AFR. I thought that the PE WOT AFR was set using Engine->Fuel Control->Power Enrich->EQ Ration vs. RPM. This table has the value 1.2744 across all the cells from 0 to 8000 RPMs.
14.4 stocih AFR (for about E5 blend) / 1.2744 = 11.3 AFR
This is what I was thinking? Is that correct, or incorrect?
For E10 it would be 1.2504 as 14.13 stoich / 1.2504 = ~11.3 AFR
Please continue...
Ive downloaded a Cobalt Stock file from the repository.
Give me some time to get comfortable with it's PE handling.
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