Leaning out!

[Reaper]

Originally Posted by Frs300

i should have done special forces instead of chair force working on jets...you at ft benning?

no i work at mountain phase of ranger school

[Reaper]

Originally Posted by jamesm

What is your ethanol content currently, just out of curiosity?

not sure, i need to invest in an analyzer among many other things. I drained both sides of the tank best i could and ended up putting in 12.3 gallons of e85 before the dyno so i figured i was doing pretty good. But that was about a month ago. The price also sudently jumped up when the warm weather hit and my cold start has fluctuated for the worse since then. What do you preffer for an e content analyzer?

[jamesm]

If you don't have an ECA.. then ethanol content isn't causing the injected volume to change at all in open loop. You have no compensation set up for it, and it's in open loop.

If you're just running E85 with no comp.. and the failsafe map is wideband input vs. map... i'd guess that the open loop afr is just off by enough to trip the failsafe.

[Reaper]

maybe im wrong but how i figured it was since i was at a lower e content before i was able to run a couple more psi before hitting the limit on the injectors. Then as the e content went up i was hitting the injector limit sooner.

[xwd]

This is why flex fuel kits exist unless your plan is to run E85 all the time from now on. I definitely recommend the Moto-East one.


Nice figures on the turbo, I have the same one coming with a JDL kit. Have a dyno printout of the 450 run?

[Reaper]

its in the fullblown owners thread, im a little lazy right now. I run e85 all the time since the turbo instal.

[jamesm]

Originally Posted by Reaper

maybe im wrong but how i figured it was since i was at a lower e content before i was able to run a couple more psi before hitting the limit on the injectors. Then as the e content went up i was hitting the injector limit sooner.

that would (could) be correct if you had a flexfuel setup, but being that you aren't applying any correction for ethanol content in open loop, you won't be requesting higher fuel volume as the content increases, and thus the PI duty shouldn't change. one exception would be the LTFT in the high bucket being applied, but that's usually turned off for an FI setup.

i'd be willing to bet that it's just the failsafe triggering due to error in open loop from the (un-compensated for) change in ethanol content.

you need a flex fuel kit. and if you're at 92% duty, some bigger injectors to be safe regardless .

[Reaper]

but if the injector duty cycle stays the same and you increase ethanol content it should become leaner at the same power. Correct? with its less caloric value as e increases.

[cf6mech]

What was your fuel level at,....take a close look at the saddle tank design on this car. My car ran great till a half a tank and lower, then would start running lean. Its a problem with this car at higher boost and suppling enough fuel. The passenger side cant scavenge fast enough to supply the drivers side regardless of what pump you use. This was with e85 which inherently is going to need more volume and at 18.5 of boost.

[Reaper]

thats intresting, but the fact is the PI was over 90% so i need injectors, or to keep it turned down.

[Reaper]

Well ive been away from my car for awhile but I took it back out today with the boost turned down to 10.5 psi and its doing the exact same thing. Full throttle at full boost the afr is good but if I lift then floor it again it leans out and I hit my failsafe.

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[jamesm]

Originally Posted by Reaper

but if the injector duty cycle stays the same and you increase ethanol content it should become leaner at the same power. Correct? with its less caloric value as e increases.

Yes it will lean out as e content increases, but it has more to do with stoichiometry and the variation in liquid density than it does with calorific value (actually, in terms of afr the calorific value is irrelevant).

The point I was making was just to say that having e in the tank isn't raising the duty cycle, because there's no compensation that would increase the ipw without an ECA.

I would argue that having an afr-based failsafe in the absence of an ECA, when running e85 is not a great idea. The open loop afr is certain to vary quite a bit without compensation for the ethanol, which is what I suspect you're seeing. Without logs and insight into the rom it's impossible to know for sure, though.

[Reaper]

I was wondering about that. Wouldn't ltft adjust though?

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[jamesm]

Originally Posted by Reaper

I was wondering about that. Wouldn't ltft adjust though?

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If it's on, and even if it is not very well. The high bucket ltft (which is what applies in open loop when it's allowed to) only cares about the 40-60g/s maf range (by default). Luckily ethanol content variation tends to introduce a global error (ie uniform across the maf range), but this is predicated on the fueling error being uniform across the maf to begin with which it almost never is in real life.

So yeah, in theory the ltft should pick up the error and apply it and all should be well, but it rarely works out so well and you can see evidence of this in logs from folks running e without flex fuel.

I've found that the best thing to do is to minimize fuel trims to the point that they're within 2% across the maf, then turn off the trims in open loop so that variations don't effect the open loop afr. This is particularly important on FI cars, which is why ecutek's documentation recommends doing this in those applications. I suppose with trims minimized to that degree you could just go ahead and leave them on, perhaps with a reduced range (default is +/- 40%, which is insane lol). If running e without flex fuel, you basically have to leave them on so that you have something compensating for e content variation, you just have to accept that the open loop AFR isn't going to be very consistent. This is why man invented ECAs .