RomRaider

Just wondering what others are running...

I have ran a few different latency values, started out with gasoline latencies and have changed a little from there (not much)... car runs well overall, fuel trims are all within 2% etc. But it just feels like my latencies could be closer... I think I have ended up tuning around slightly wrong latencies with my MAF scaling... maybe I'm just being way to anal and need move on. I am one of those that flash's my car usually 1-2 times per day it's driven, always fine tuning etc.

Anyway, for those on E85, what kind of latencies are you running, and why? and how well does it run for you? Any input would be great... I would like to play around and see what kind of changes it makes.... and maybe it will come in handy for others running E85.

Thanks!

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I wouldn't have thought to consider that latencies might be different for E85 vs. straight gas.

Trying to get my head around why they would change.

Also moving on to E85 - love it

Thats kind of where I'm at-

Doesn't seem to me that they would need to change.... still the same hardware....

But, if I run the injector tool it wants me to change.. Also, I have seen different numbers from different people as to what set of latencies is "actually" correct for the mod'd top feeds... so kind of looking for some different opinions on that as well....

And yes, E85 is just plain Wonderful... at 11.8-11.9 AFRs my EGT's are still arond 1400ish!!

Just to chime in, I am tuning in my modded stock injectors on my 02 WRX at the moment. I'm also transistioning to E85. My blend at the moment is in the E50 area.

I'm not sure how much I want to post yet as I'm still working out some issues myself, but here is a bit of information...

When I was on gas, I set my injector scalar to 825 cc/min (I had my injectors flow tested, they ranged from 822-832, I just picked 825 because it seemed like a nice number in the middle).

This, as many, many folks before us have ran into, causes you to run super lean at idle. There are many discussions on naisoc and romraider about what to do from here, but for now, I chose to modify the injector latencies.

Look at this thread. It has been helpful to me:
http://forums.nasioc.com/forums/showthr ... ?t=1114228

Now, with my injector scalar at 825 and my latencies modded, my car ran fine but not perfect. My AFR's aren't rock steady, but they are in the right range. Again, it runs fine, but not perfect.

Some will argue that you need to mess with tip-in, MAF, latencies, scalars, etc. I haven't found my perfect solution yet.

Now, since I got it running okay on gas, I dumped 10 gallons of E85 in the tank. I chose to rescale my injectors -20% for that, and ultimately, when I'm finally on "pure" E85, I'm going to rescale my injectors to 600 cc. I'm hoping that this will be close enough to the stock scaling that I don't have to mess with tip-in or MAF, and that I can dial back what I have done with the latencies.

Also, just an FYI, when on gas, I set the injector scalar to 550, and it idled right. Of course, it ran pig rich off idle. This told me that the latency needed to be messed with. Perhaps tip-in too, but I haven't gone there yet.

So, at 600 cc, I'm thinking I will be able to dial back my latencies and have it idle fine.

Use the latencies at the end of the first post in the referenced thread. They will be the same for E85. Change your scalar to about 575 or so and you should be good to go. You'll have to adjust based on the fuel in your area, but 575 should get you relatively close.

FYI I'm running 100% E85 on modded stock injectors.

Yea.. my scalar is 574 (or it was before I did the MAF hack)

Generally you multiply your tip-in table by the percentage you get when you divide your old injector scalar by the new scalar... although this is another area I have had to play with a bunch and it's still not quite right- actually this was partially why I thought my latencies might have been a little off.... because I could not seem to get tip-in just right. It's perfectly driveable, but when I log some things related to tip-in I see my AFR's jumping around more than they should.. and regardless of what I did with my tip-in table, they always jump around (Just do it differently)...

For those on E85, with mod'd injectors, what does your tip-in table look like?? maybe this would be another area we could compare and talk about the results....

I did the same as you did for tip-in. I also did the same to the primary open loop fueling compensation (coolant temp) table which was huge to getting the car to idle right when warming up ifit was anything much below 60F.

What mods did you make to tip-in?

Also, what MAF hack are you talking about?

The 300 g/s workaround hack


It seems to like it slightly richer tip-in than what I would have thought....

Okay, gotcha. My 02 WRX wanted more tip-in when it was stock even. If I recall correctly, I added 150 points to each cell to get the AFR's to transition quickly enough even in my "Stage 1" tune. Tip-in wasn't tuned right from the factory in my opinion.

570 scalar
latency
6.5 9.0 11.5 14.0 16.5
3.30 2.10 1.48 1.14 0.90

I have seen different injectors run different latencies with the 11.5 value needing to be higher and the 14.0 being lower. but the car will probably idle well