Best way to stabilize cold starts with E85 on 3.5 ecoboost??

[Davem3261]

What is going to happen when you go back to pump gas? Will you have 25% too much fuel?

[Perna00]

I think I might have to send a trouble ticket into HP tuners. I tried adjusting the 25% up on the flex fuel coldstart chart but it didn’t do anything until I made it on the regular coldstart chart. It should go off at two different tables, based on the ethanol percentage.

[Davem3261]

Would you consider turning off flex fuel and setting your AFR for pump gas? That would fix all your cold start problems. You can add up to 30% ethanol and your fuel trims will add the 10% extra fuel needed. You have 3 degrees less timing than my E50 tune and your on E85. If you set up your LSPI tables correctly it will get you 20 PSI on E30 and reduce boost a few pounds on 93 when it sees knock.

[Perna00]

I’d like to keep the flex fuel if possible. Unfortunately there is only one E85 station around me, it isn’t the most convenient, and it’s also decently sketchy so having the buffer for if percentages change or mixes change is nice. Especially if I have to put some premium gas in for when they are out of E85 and the worst part…having to try to explain to my wife for the few times she has to get gas on how to figure out how to mix it or why! ��

The truck started pretty decent today in 40 degree weather with just little mis between 3-10 seconds but nothing even close to before. I’m not sure if I’d even consider it a miss.

I got my LSPI set up to limit boost right at 20 PSI. I’m only 5 degrees advanced on E85 right now because there isn’t a dyno around Savannah, GA and I haven’t had the time to try to datalog runs on the back open roads yet. I’ve heard you can just about run MBT on E85 and even lean out safely to about 10:25-10.5 AFR but I still need to do some extra research and testing. My main concern is keeping it below the integrity of the internals. I found that 650 torque is about the limit for a non-high output 3.5 and I’m already slightly over 600.

[Davem3261]

your not picking up what I'm putting down. If you follow my suggestion you can run up to E30 or 93 on the same tune. This is exactly what I do with my explorer ST. My wife can fill up with 93 or I can put E85/93 mix in it. No tune changes. Flex fuel doesn't work in an ecoboost. You already know this because your are not anywhere close to where you need to be on straight E85 timing. You are currently running E30 timing, have your LSPI tables reduce boost for 93. Dedicated E85 tune is required.

[Perna00]

I do appreciate the advice. This is the first vehicle I’ve tuned with HP so I’m still learning as I go. After I get the fine adjustments with this starting, I’ll be saving this tune as a 93/flex tune. This will be a safe tune for if E85 isn’t available or my wife has to get fuel and there is still E85 left in the tank.

I will be working on a dedicated tune just for E85 as my next step. I’ll need more time for it since there will be quite a bit of datalogging and eventually I’ll have to travel to a dyno site. When I started the tuning, I was full speed ahead but with the holidays and life happening, I haven’t had a lot of time lately.

[Perna00]

I?m slowly getting it under control. I increased the flex fuel cold start and it did increase my fuel/air ratio but only slightly because it is all percent based on ethanol content, so it is not the full range all of the time. I added 10% increased fuel and it starts very smoothly for the first 2 1/2 seconds, and then sputters up to about 10 seconds. I noticed in the fuel decay field that it was actually taking away fuel so I revamped it blending up to about 90? by feathering about 10% additional between the two second and 13 second mark. I?ll have to wait for another colder morning to set the lower values but so far it seems to be starting and idling perfectly. I have a feeling that at each temperature range, I?m going to have to keep changing my tables around until I find the perfect graph for all temperature settings. I?d be more than happy to share the results after I am finished with it if anyone else is interested.

[Perna00]

I’m running across a few questions. I’m trying to figure out the background to try to get this more solid of a solution for cold starting with ethanol. I’m trying to research it but got a few questions that might pertain specifically to our engines. If anybody can offer some insight, I’d appreciate it…

I’m trying to figure out if vehicles cold starts (first 20 seconds after start) easier with port or direct injection. I was told port injection was easier, but some people are saying that the atomization of direct injection makes it easier to fire. They say port can clump fuel droplets up along the valves. It does seem like the truck starts easier with it heavier on the port injection side. I know whenever it is starting, it is using 100% port injection.

I was watching the timing on the truck and whenever it starts it is around 10? before top dead center. During the first 20 seconds of running it actually goes after top dead center which I’m assuming with the cam overlap is what helps warm up the oxygen sensors. Since it initially starts perfectly every time, and it’s the idle that is an issue… Could it be with the burning rate of ethanol that’s causing it to fight against itself with the overlap? If so, should I possibly advance the timing more towards top dead center versus having such a large overlap?

Lastly, I’m reading that some people have to go down as low as .4 lambda in order to stabilize cold starting for the first 20 seconds. This seems extremely rich to me and right now I’m working around .7-.8 during the first 10 seconds. I can probably figure it out through time but one cold start per day is taking forever with only being able to change one variable versus all the different temperatures and settings I have to mess with. Any basic background or knowledge that can be applied would be greatly appreciated.

[Davem3261]

I can help fix all your problems. Turn off flex fuel. Set AFR to 13. Put all cold start settings back to stock. E30 in the tank. Run 93 if you want, LSPI will reduce boost automatically. Same performance as you have now and perfect starts every day. Done.

[Perna00]

I follow you but my goal is to start working on a dedicated E85 tune after I get it stabilized. This tune works for a basic flex or 91/93 mix. I want to more forward with just an E85 tune, but I’m currently trying to fix the cold starting and trying to understand all the characteristics versus just changing variable “X” to “Y” just because “Z” says to do it. After the starting is better, I’ll more to timing and AFR.

[Perna00]

So I have been messing with MANY tables and variations with the cold starts. I started analyzing how it starts so easy and bogs down afterwards and it seems that I have figured it out (or at least for now). Credit goes to engineermike for the assistance on a few tables I was unaware of but it seems that .1-.2 lamba increase on the cold starts and removing the 20+ degrees of retard that the CSER commands made it start and idle flawlessly in colder weather. Hopefully this helps someone else fighting with it and I?ll update with any changes.

[Perna00]

So I’ve had some of the coldest days lately where I’m at and even though the truck is starting better with the timing, I’m still having a very rough 5 to 10 second start. I was doing some research and found out that with the flex fuel enabled, The startup ffv lost fuel and ffv decay charts are what the engine uses in order for starting fuel. Unfortunately, HP tuner does not give you access to these tables. PCM tech does and another member showed me the equations and tables that are accessible with their software. I have sent some support tickets to HP about possibly adding these tables so that I could Finish Tuning based on their flex fuel enabled option with no help. Their response was that “they have given all parameters to tune the vehicle“. It seems to me that if there are tables that the vehicle uses when you enable flex fuel with their programming, they should give you access to them, but I’m getting nowhere by messaging them. Hopefully someone can step in and help me out before having to change Tuning platforms.