ECMlink e85: Idle Issues. Only Getting .14 airflow per rev

[boostadd1ct]

trying to calibrate my car and I pretty much got it except this idle issue.

The FT is all lined up. LTFT lo is 1+- at cruise and LTFT Hi is .8 at cruise
Combined fuel trim is close to +-8 for the most part.


Idle however is another issues. as far as fuel trim goes its looks good i think. except it doesnt idle that well and sort of miss fire at random.

This car had idled much nicer with a different deadtime and uncalibrated maf. BUT the fuel trim was out of wack at cruise and idle.

The only thing I can think of that is off is airflow per rev. but when I try to raise it, it throws the combined fuel trim off and idles much much worse.

any ideas?


boost leak done at 30psi.
base timing verified.
new:
wires/plus/coil
fpr/fuel filter/wally
bosche 1600cc
3" gm maf
272 cams
hy35 holset turbo
3" open downpipe

on an aem wideband thats been calibrated so yes its accurate WB reading.

the only thing I can think of is maybe raise the idle timing more?

Note: this log is after FT reset and then cruised 10 min.

 

[snowborder714]

I really don't like how big of a jump your MAF Comp table makes. I know the GM MAF sometimes takes some extreme values to get it in tune, but your table seems to be way out of whack to me.

What does your idle look like with the whole MAF Comp table (or at least the lower values for idle) zeroed out? When you lower the MAF Comp sliders, you bring down your AirFlowPerRev. I'd bring those values at the beginning back up and see what AirFlorPerRev does - it should go back up towards .25 or so, which is your target. Then you'll adjust deadtime to get CombinedFT to cycle around 0%.

 

[c2ypt1c]

Yup, raise up the maf comp sliders at idle while adjusting the fuel. Many people seem to think that the global fuel value is set in stone, when in fact each injector behaves differently (especially at idle) and it may need some experimenting with. A nice "trick" that I like to use is to lock the ecu in open loop and try to get wideband factor down to zero (assuming deadtime is reasonable). It's a balancing act between airflowperrev, global fuel, and deadtime. With the linearity problems of certain injectors, it can be a "not-so-easy" process, for lack of a better term

 

[snowborder714]

Also keep in mind those injectors will probably idle or cruise well, but not do both. Just the nature of something that large.

 

[boostadd1ct]

Also keep in mind those injectors will probably idle or cruise well, but not do both. Just the nature of something that large.

Interesting. I thought with e85 ill br able to get both.

How does the global % affect fuel trim?

Curious if i can raise deadtime and lower gobal % if that would keep the FT inline?

The car idled great with higher slider and higher deadtime but fuel trim at cruise is mest up.


Raising deadtime would raise my LTFT lo to like -12.5 at cruise. Is that acceptable?

 

[snowborder714]

E85 doesn't provide a magical fix for the issue with large injectors. It might make it less of an issue, but my guess (and from the data I've seen from ECMTuning's injector testing) is it'll still be there. You may have already noticed this as you said you can get it idling well, but then cruise is messed up.

If it really is that big of an issue that you're seeing a -12.5% LTFT Lo value while everything else is in check, then you have a few options. You can swap out the injectors for something smaller and more manageable. You can meet them halfway and get both idle and cruise as close as you can, while understanding they aren't going to be perfect. Lastly, you can just live with it (probably the least ideal option).

Global % shouldn't be used to adjust fuel trims. That will only be deadtime and MAF Comp sliders. Global % is used, for example, if you're seeing VE values in a speed density setup that are way above 100 in the SD table.

 

[boostadd1ct]

E85 doesn't provide a magical fix for the issue with large injectors. It might make it less of an issue, but my guess (and from the data I've seen from ECMTuning's injector testing) is it'll still be there. You may have already noticed this as you said you can get it idling well, but then cruise is messed up.

If it really is that big of an issue that you're seeing a -12.5% LTFT Lo value while everything else is in check, then you have a few options. You can swap out the injectors for something smaller and more manageable. You can meet them halfway and get both idle and cruise as close as you can, while understanding they aren't going to be perfect. Lastly, you can just live with it (probably the least ideal option).

Global % shouldn't be used to adjust fuel trims. That will only be deadtime and MAF Comp sliders. Global % is used, for example, if you're seeing VE values in a speed density setup that are way above 100 in the SD table.

Ya i will try to calibrate in between. This bad idle is really worse when cold. It didnt even want to idle by itself this morning. Thanks and will rrport back when i get some tuning done