so i was reading that in the cold , e85 actually drops points is this true ?

and if so im assuming the best thing to do is lower boost ?

 

Mine dropped from 11.8 a/f ratio to ~13 . Maybe because I'm running out of pump strength. Double pumper is too expensive, Boost-a-pump sounds like a better alternative for me.

 

eek, ill have to pay attention to the afr 's , thanks.

 

ya it drops quite a bit. keep 12.0-12.2 for best performance.

 

I went from about 12.0 to almost 13.0 with the recent colder temps in Houston.

Also, it idles very lean and has trouble starting. I'm going to try increasing the value for colder temps in the cranking enrichment table. Also, while its running in open loop before it warms up, its very lean in the low load cells. Should I just richen up the fuel map in that area?

 

There are two issues at play here. First, places with colder climates alter their mixture of E85 in the winter. A lot of places, this can be as low as 70% ethanol content. This added petroleum will case a richer engine mixture. Second, temperature changes affect load values and may cause the car to hit different fuel map locations than when tuning. That's not really a problem with the fuel. Rather it's a result of insufficient tune adaptability.

Especially for a street car, it's important to set sensible map values well beyond what you expect to encounter. You don't want small failure (such as a sensor) or altered running conditions to have catastrophic results.

d

 

No its not caused by the different ethanol mixtures. Ive confirmed this with a test sample. stays 85% here year around. Also in the summer time the AFR's will go from 11.9 during the day to 12.4-12.6 at night. ethanol jumps around quite a bit , theres nothing you can do on the stock ecu to correct this to my knowledge.

Also the way I map, it can go from over 100 load diff and still maintain the same settings.

 

Yeah, my E85 stations appear to use the same ethanol content year round (I have a FF sensor and gauge), and my car goes lean when it gets cold. I'm still puzzled about what causes it. I keep thinking that it has something to do with the low vapor pressure of ethanol causing poor atomization with cold air (and cold E85). I think gasoline may do the same thing but to a lesser extent because when I was running on pump gas, it would also go a little leaner in the winter. It could also simply be that the global air density scaling table is not accurate, and airflow in cold weather is being underestimated.

For the past few winters, I've just been richening up the fuel map ~1 pt, but this year, I'm going to fix it either with the global air density table or using the airtemp/baro compensation table for fuelling. The choice depends on what I think is happening in cold weather.

 

keep me updated on what you find please, that would be great if you can solve this problem

 

Interesting. Sorry I jumped to conclusions. It's been pretty cold out here the past few weeks, but my car has been parked since the end of the racing season.

I was thinking about going out for some lapping tomorrow. I'll try to get some logs and see if I experience it too...

d

 

I have been having issues down here in south FL as well. The temps are dropping here right now because of all the cold air shooting down from Canada. Its about 70 degrees during the day and it drops to 40 at night now. Its nuts.

It now takes me literally 6-10 cranks to start it in the morning, then as it tries to settle in idle it boggs out and dies. So im forced to tap the gas ever so slightly to keep the RPMs bouncing around 1.5-2 rpms to let it heat up a bit. And now for the best part, it idles between 16.8-17.8 on the AFRs!

However driving is normal, but i noticed some boost issues, i may be overboosing but im too scared to push it and blow my piping all over the road. When i get some time this weekend ill inspect everything properly. Im on the same E85 tune that i got 4 months ago, at 32psi btw. Hope this helps, maybe someone has a tip for me ?