trying to wrap my head around E10

[efizjb]

Sorry guys, Joecar, I've been away a bit, I'm using V2

[WeathermanShawn]

efizib:

Refresh our memories as to what OS and PCM and type of tune you are using. Is this Flex Fuel or are you utilizing the LS1-type PCM?

Does your tune utilize Trims? And what is your WOT fueling set for?

Sorry for the additional inquiry. Sometimes it is best for all the readers following the thread to get a good summary.

Thanks.

[joecar]

If you have V2 then you should use the serial AFR/Lambda capability...

See post #3 here: showthread.php?9340-serial-port-cable-that-goes-to-v2

Also see post #8 here: showthread.php?14351-BBL-PIDs-V2&p=128785#post128785

The serial AFR/Lambda gives better data which has immunity from analog voltage offsets and induced ignition noise.

[efizjb]

Thank you Joe!

Shawn, I'm just running a 2002 LS1 OS, CL nothing out of ordinary.

I guess I'll simplify my question from what I know and see if it clicks in my head.

When I last dyno'd the car last year not even thinking of E10 as being part of the equation, stoich was factory setting (14.63) and LC-1 also set for same stoich. My VE and PE #'s were pretty damn accurate for street tuning only. My PE was set for 12.9 and the whole pull was between 12.8 and 13.0 on both the dyno O2 and also the same on my LC-1.

Now what confuses me is the statement the LC-1 is going to read lambda no matter what the ECM is set at. I understand the LC-1 doesn't care what the setting the ECM is, that I get...

Now with all the aforemetioned, if I were to go in and ONLY change stoich in the ECM for E10, would the same dyno pull now read say 12.2-12.4 assuming .6 diff in stoich for sake of using a general # (not changing stoich in LC-1 software, I understand it won't be an exacty .6 due to percentages etc, just using as a general # for this example....)

If I can understand what this scenario would look like, I think I can digest this. I can then go to using lambda from there, I just gotta understand it in a language I know first lol
on my LC-1

[5.7ute]

Your wideband would still read the same as before in the scan tool, but the scanned commanded AFR pid (GM.AFR) will change.
This is due to the PCM doing all its commanded fuelling calculations in EQ ratio. Basically after it has calculated the commanded EQ ratio it divides stoich(B3601) by this amount to give it a value for the IPW calculation.

[efizjb]

Okay, making sense now, thanks Ute. Based on that, I take it I am probably in an unsafe WOT PE. I guess it makes sense to change the stoich for E10 and go at all of this again...

[WeathermanShawn]

Yea try that.

Your question intrigued me enough to do some experimenting myself. I have been logging differing B3601's, LTFT's and WOT Fueling. You will see your Trims adjust and WOT PE fuel needs to be tweaked by about 4%.

That tweaks the airmass calculation by a similar amount. A lot of it did not make sense until I tried it out..

[5.7ute]

You can get away with going from normal pump gas to e10 without any major concerns, as the fuel trims will add the necessary percentage to the airmass estimation. (As long as you stay away from WOT until the trims have had sufficient time to calculate the change)
However. if you went the other way & used pump gas on an e10 tune, since negative trims do not carry over into WOT you will be too rich under these conditions.
Personally, I classify the fuel as a piece of hardware, & calibrate the PCM to suit.

[WeathermanShawn]

Ultimately I found the IBPW1 to be nearly the same with an E10 Tune vs E0. The Trim function in closed-loop make it virtually identical in non-PE mode.

WOT say a 'richer' AFR (same EQ), but my airmass also decreased by about 3-4 %, again making the final IBPW1 nearly the same.

I get the concept, sometimes I wonder if it is really necessary on LS1? It is lot of work and seems 'circular' in the final results.

Anyway, the subject has been well-discussed. OP, let us know your results and if you make any conclusions.

Good luck.

[joecar]

Just remember this:
- Lambda is not specific to any particular fuel,
- AFR is specific to a fuel's stoichiometric AFR,

AFR = Lambda * stroichAFR