"Miss" under throttle on cold E85 car
Feb 25, 2010, 10:42 AM
#1
"Miss" under throttle on cold E85 car
I've had this happen on my can and one other, and for the life of me cannot see anything in the logs that can tell me what is going on.
Basically, if you cold start the car ad try to drive, it runs fine at idle and very light throttle, but will miss horribly (feels like fuel cut) with throttle about 1/2 the time. It will most always miss the first time you try to accelerate, then be fine if you let off and try again. I'm not talking going WOT on a completely cold engine, just pressing the throttle to about 30% to climb a small incline in 1st or 2nd.
The issue persists for a couple of minutes when first driving the car and gets better as the temp climbs. The car doesn't do this on 93 oct.
Logs show severe timing pull -20º in some instances, but not all. Fuel is in check for the area when the issue occurs (around 0-2 psi and ~13.5 AFR [gasoline]). IPW% is fine and timing usually looks good aside from that weird -20º I saw.
So, in short, it seems that when it crosses to open loop on a cold engine it's just yanking out the timing for no reason and completely cutting the engine (revs fall really fast).
Any thoughts?
Basically, if you cold start the car ad try to drive, it runs fine at idle and very light throttle, but will miss horribly (feels like fuel cut) with throttle about 1/2 the time. It will most always miss the first time you try to accelerate, then be fine if you let off and try again. I'm not talking going WOT on a completely cold engine, just pressing the throttle to about 30% to climb a small incline in 1st or 2nd.
The issue persists for a couple of minutes when first driving the car and gets better as the temp climbs. The car doesn't do this on 93 oct.
Logs show severe timing pull -20º in some instances, but not all. Fuel is in check for the area when the issue occurs (around 0-2 psi and ~13.5 AFR [gasoline]). IPW% is fine and timing usually looks good aside from that weird -20º I saw.
So, in short, it seems that when it crosses to open loop on a cold engine it's just yanking out the timing for no reason and completely cutting the engine (revs fall really fast).
Any thoughts?
Feb 25, 2010, 11:05 AM
#2
I've had this happen on my can and one other, and for the life of me cannot see anything in the logs that can tell me what is going on.
Basically, if you cold start the car ad try to drive, it runs fine at idle and very light throttle, but will miss horribly (feels like fuel cut) with throttle about 1/2 the time. It will most always miss the first time you try to accelerate, then be fine if you let off and try again. I'm not talking going WOT on a completely cold engine, just pressing the throttle to about 30% to climb a small incline in 1st or 2nd.
The issue persists for a couple of minutes when first driving the car and gets better as the temp climbs. The car doesn't do this on 93 oct.
Logs show severe timing pull -20º in some instances, but not all. Fuel is in check for the area when the issue occurs (around 0-2 psi and ~13.5 AFR [gasoline]). IPW% is fine and timing usually looks good aside from that weird -20º I saw.
So, in short, it seems that when it crosses to open loop on a cold engine it's just yanking out the timing for no reason and completely cutting the engine (revs fall really fast).
Any thoughts?
Basically, if you cold start the car ad try to drive, it runs fine at idle and very light throttle, but will miss horribly (feels like fuel cut) with throttle about 1/2 the time. It will most always miss the first time you try to accelerate, then be fine if you let off and try again. I'm not talking going WOT on a completely cold engine, just pressing the throttle to about 30% to climb a small incline in 1st or 2nd.
The issue persists for a couple of minutes when first driving the car and gets better as the temp climbs. The car doesn't do this on 93 oct.
Logs show severe timing pull -20º in some instances, but not all. Fuel is in check for the area when the issue occurs (around 0-2 psi and ~13.5 AFR [gasoline]). IPW% is fine and timing usually looks good aside from that weird -20º I saw.
So, in short, it seems that when it crosses to open loop on a cold engine it's just yanking out the timing for no reason and completely cutting the engine (revs fall really fast).
Any thoughts?
I've just gotten used to babying the car for awhile before giving it more throttle. By the time I reach the end of the block the issues are pretty much gone and temps have reached enough to make the car fire properly. My guess is the e85 is having major issues vaporizing in the cold. I fully expect this to disappear when around spring and air temps are above 40F.
Trending Topics
Feb 26, 2010, 08:43 PM
#8
Evolved Member
iTrader: (22)
Join Date: Nov 2003
Location: Northern KY near Cincy
Posts: 2,408
Likes: 0
Received 6 Likes
on
6 Posts
For those that are having this problem is on the 8859 (IX) rom.
There are 3 "Low Coolant Temp Trim" tables and in stock for they pull down in the -33 region. From my understanding these tables are controlled by the "Percent Low Temp Timing vs Coolant Temp" table. The 100s in this table mean that the timing pull in the "Low Coolant Temp Trim" tables will be fully used.
I recommend disabling the tables by setting the 100s to all 0 to see if your condition improves. OR adjust the "Low Coolant Temp Trim" tables to not allow such low timing pulls.
ALSO....
Ensure your "Target Minimum Idle" table has higher rpm setting in colder temps.
You will also need to ensure the MIVEC isn't affecting the idle when cold.
There is a neat table called "MIVEC Max vs Coolant Temp". You might try lowering the max limit to 0 when the engine is cold.
This gives you some areas to try. I will post up some VIII settings later.
Paul
There are 3 "Low Coolant Temp Trim" tables and in stock for they pull down in the -33 region. From my understanding these tables are controlled by the "Percent Low Temp Timing vs Coolant Temp" table. The 100s in this table mean that the timing pull in the "Low Coolant Temp Trim" tables will be fully used.
I recommend disabling the tables by setting the 100s to all 0 to see if your condition improves. OR adjust the "Low Coolant Temp Trim" tables to not allow such low timing pulls.
ALSO....
Ensure your "Target Minimum Idle" table has higher rpm setting in colder temps.
You will also need to ensure the MIVEC isn't affecting the idle when cold.
There is a neat table called "MIVEC Max vs Coolant Temp". You might try lowering the max limit to 0 when the engine is cold.
This gives you some areas to try. I will post up some VIII settings later.
Paul
Mar 1, 2010, 07:00 AM
#10
I tried Appauldd's settings and they worked out pretty well. I didn't drive it right after start up though (I wasn't running late for once 
). I noticed the cold idle was much better than normal and I would assume the cold driveabilty would be better also. Thanks for the help. Much appreciated. It's a good feeling when one of those little bugs can get worked out.
). I noticed the cold idle was much better than normal and I would assume the cold driveabilty would be better also. Thanks for the help. Much appreciated. It's a good feeling when one of those little bugs can get worked out.
Mar 3, 2010, 07:42 PM
#12
Evolving Member
In my opinion this is where the automakers have sharply increase cold start enrichment on their FFV's. The situation you guys are describing is a very common issue on E85 mods and even more so with non-modified non-FFV's running straight E85. When you first cold start the engine on E85- you are really igniting the gas portion of the E85- and at 15-30% of the fuel volume- it will take a lot of fuel the first minute or so until the heat is just enough to fully vaporize the ethanol portion and get it ignited. While this is also true of gasoline- which has a distillation range of let's say 100 degrees thru 375 (E98 is all 173 degrees)- winter gasoline will carry a vapor pressure of 10-15 lbs where E85 will be about 8 1/2 lbs (this would be pressure buildup at 100 degrees F) . Vapor pressures are different for gasoline in different markets per EPA regs and E85 will also vary per season, % blend, and type of gas used in the E85. Look at it this way- if lets say 15% of straight gas is easy to ignite and with high vapor pressure that 15% is a larger quanity of ignitable fuel than 15% of the 15-30% gas in E85. E98 only has a vapor pressure of 2.3 lbs and cools the compressing charge- thus the automakers asked for winter blends of E85 to be E70 and then they also program the ECU to further enrich on cold start.
Any way in cold weather you can add additional gas in your tank mix without messing with your tune, OR program your cold enrichment, OR keep a tiny amount of heat on the fuel rail (I have seen some strategies on this), OR in the future we can hope for something like the Delphi heated injectors that are being developed for Brazil's hydrous (HE100) ethanol FFV's ?(they do not use any gasoline but the ambient temps there are warmer) I understand Delphi has a precious few of these also here in the states being tested.
BTW- an FFV Taurus I drive also has the timing pulled way back the first few seconds until the high idle slows- she will not come all the way back to 25-35 degrees until near full heat. Not sure about our Impala FFVS.
Any way in cold weather you can add additional gas in your tank mix without messing with your tune, OR program your cold enrichment, OR keep a tiny amount of heat on the fuel rail (I have seen some strategies on this), OR in the future we can hope for something like the Delphi heated injectors that are being developed for Brazil's hydrous (HE100) ethanol FFV's ?(they do not use any gasoline but the ambient temps there are warmer) I understand Delphi has a precious few of these also here in the states being tested.
BTW- an FFV Taurus I drive also has the timing pulled way back the first few seconds until the high idle slows- she will not come all the way back to 25-35 degrees until near full heat. Not sure about our Impala FFVS.
Last edited by 1outlaw; Mar 3, 2010 at 07:52 PM.
Aug 5, 2010, 10:21 PM
#14
EvoM Community Team Leader
Im having this same problem on my 8. When cold it stumbles hard with any throttle or load input. The condition goes away quickly once the engine starts to warm up. Ill see if i can find some cold temp tables to mess with
Aug 10, 2010, 09:16 PM
#15
Not sure if this would have worked on the IX, but I noticed this on my X:
When I lowered my low coolant temp timing reduction table it exacerbated the problem, but if I increase fueling in the low load / RPM cells where I'm having the problem it seems to help. I'm guessing the car is running some type of open loop until it thinks the O2 sensor is warmed up, but I'm not sure. Either way its something to try.
When I lowered my low coolant temp timing reduction table it exacerbated the problem, but if I increase fueling in the low load / RPM cells where I'm having the problem it seems to help. I'm guessing the car is running some type of open loop until it thinks the O2 sensor is warmed up, but I'm not sure. Either way its something to try.