Tuning for E85

[picnic_george]

If I am tuning on a gas scale (14.7) will that really mess up the VE table since obviously E85 uses about 30% more fuel? I assume it will make a 90% VE look more like 130% which is obviously not correct.

If commanded is set to 9.7:1 in the PCM will that make the VE table look more like it should or does that not matter one bit?

Thanks
Kris

EDIT~ I should say not commanded, I meant AFR for stoichiometry. Possibly commanded as well lol

[joecar]

Hi Kris,

If you use lambda, then everything remains the same...

First, set B3601 to AFR 9.7; since this will use more fuel, you have to make sure your pump/injectors can flow the extra fuel.

So, then:
- CL = lambda 1.000 = EQR 1.000 = AFR 14.7 for E00 = AFR 9.7 for E85;
- PE = lambda 0.860 = EQR 1.165 = AFR 12.6 for E00 = AFR 8.3 for E85;

i.e. leave the VE table alone (it models air, not fuel);

if you need to run richer than lambda 0.86 (EQR 1.165) then edit the PE table B3618.


BTW: set the tunetool to view fueling units in EQR or Lambda, and use calc pid to view wideband in EQR or Lambda.
BTW: set the tunetool VE units to g*K/kPa, this will give you more insight into the cylinder airmass.

[joecar]

You will find that you can run more timing advance... this may alter VE, so you may need to hone the VE table if you change timing significantly.

[picnic_george]

I got all that. Think I worded my question wrong. I know the VE table should be the same, but if you don't change those settings the VE table will be out of fubar when the car gets tuned, is what I'm asking. Will the PCM automatically figure commanded to say 8.3 for PE not stick at 12.6? Just wondering if you change just B3601 will everything else just figure itself out? I.E B3606, 3605, 3618, B3602, 3603 etc etc

Thanks Joe

[swingtan]

I couple of tips for migrating to E85, and assuming you are not trying flex fueling...

First, get your VE table and fueling spot on for ULP before going to E85. The engine airflow will not change significantly with E85, but the ethanol percentage may not be exactly as you expect. If the airflow (VE table / MAF calibration) is spot on for ULP, it helps dialing in the "E85" stoichiometric ratio.

Once the engine airflow is correct, fill up with E85 and calculate the expected ethanol percentage from the amount of E85 added. For example, if you added 60L of E85 to a 75L tank, you had 15L of ULP already in the tank. So you have closer to E68 in the tank now. Set the stoich AFR to this value, 10.8:1 in this case.

Make sure the STFT's are on and watch them when testing. If you were off on your ethanol percentage calculations, you'll see the trims correcting. This is why it's important to get the fueling right on ULP, so that you know what's happening when you swap to ethanol. Get an average of the STFT's and correct the stoich setting to bring the trims close to an average of "0" and this will give you the real stoich setting for the fuel in use. Remember that on the next tank full, you'll need to reset the stich ratio as the fuel will be much closer to E85.

Once the base setting in B3601 or B3671 (depending on the controller), the rest of the fueling tables will follow the stoich ratio.

Also, remember that Lambda "1" is the stoichiometric ratio for any given fuel, hence the trick to swap to tuning in Lambda instead of AFR. If you log commanded fueling in lambda and set the wideband to display lambda, you simply need to make the two traces match. This also goes with the NBO2's as they also only measure Lambda, so the STFT's will automatically be correctly trimming for any fuel used.


Simon.

[picnic_george]

The setup in question has too many changes for that to be a reality. This is going from a pump gas nitrous motor to a COS3 20+ psi turbo combo. But I was pretty sure if you changed something, it would all fix itself. This was more of a general question to be sure I'm looking at numbers correctly. What even sparked this question was someone asking me how a FAST wbo2 will read E85 and I said it didn't matter because they read lambda not AFR it will just be displayed as if it was gasolone. He thought becuase the gauge had a range of 10~20:1 that it wouldn't read e85. I said all 14.7 is, is a calculation based on lamda. I was then second guessing things and decided I wanted to ask what needed to be changed on your average e85 conversion. I like looking at AFR numbers, people like to see that and know what those numbers mean, granted I don't mind seeing 12.8, .87 or 1.14 but AFR is just easier for all parties involved.


Once the base setting in B3601 or B3671 (depending on the controller), the rest of the fueling tables will follow the stoich ratio.
Simon.
That's what I was hoping I'd hear.
Thanks Simon

[joecar]

I got all that. Think I worded my question wrong. I know the VE table should be the same, but if you don't change those settings the VE table will be out of fubar when the car gets tuned, is what I'm asking. Will the PCM automatically figure commanded to say 8.3 for PE not stick at 12.6? Just wondering if you change just B3601 will everything else just figure itself out? I.E B3606, 3605, 3618, B3602, 3603 etc etc

Thanks JoeAh, I see...

Yes, if B3601 is not set for the fuel being used, then when VE gets tuned it will have a scaling baked into it.

B3601 is in AFR units, all the other fueling tables are all in EQR units (set your tunetool fueling units to EQR).

So for example, when PE activates it commands the EQR mentioned in B3618 (say EQR 1.165)... this gets converted to AFR using B3601...

i.e. all the other tables are converted from EQR to AFR (based on B3601)

(i.e. it is easier to think of the PCM commanding EQR rather than commanding AFR).

[cyipher]

Ah, I see...

Yes, if B3601 is not set for the fuel being used, then when VE gets tuned it will have a scaling baked into it.

B3601 is in AFR units, all the other fueling tables are all in EQR units (set your tunetool fueling units to EQR).

So for example, when PE activates it commands the EQR mentioned in B3618 (say EQR 1.165)... this gets converted to AFR using B3601...

i.e. all the other tables are converted from EQR to AFR (based on B3601)

(i.e. it is easier to think of the PCM commanding EQR rather than commanding AFR).


What happens if you dont chnage the other tables (PE) to read in eqr? is the change on the efilive side (viewing) or is it in the ECM side of things?

[picnic_george]

The PCM reads EQR so I would assume when you change stoic to 9.7 all AFRs listed on EFIlive should automatically change as well, that's in efilives software not gms hardware. I'll try it and find out :)

[joecar]

The PCM reads EQR so I would assume when you change stoic to 9.7 all AFRs listed on EFIlive should automatically change as well, that's in efilives software not gms hardware. I'll try it and find out :)Yes, correct.

[joecar]

What happens if you dont chnage the other tables (PE) to read in eqr? is the change on the efilive side (viewing) or is it in the ECM side of things?The AFR translation is done in the EFILive tunetool software.