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will15

Cold start e85

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Looking for some cold start info for e85, for both flex fuel os and standard os. Iv have played with some cranking tables and  temp related lambda tables and improvements are little for the changes iv made.

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Have you played with both fuel and spark tables, or just the fuel tables? 

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In hp tuners I changed the cranking lambda and it made it start easy but die straight away. I then found another table that had fuel enrichment coolant correction temp vs time or something, that was completely zeroed out. I added a value that I can't remember off the top of my head to decay for about 10 seconds and it fixed it.

There may well be other stuff to change to make similar or better cold starts but I never played with it for long enough to go through everything.

I know it's not the same as pcmtec but the same tables and scalars etc are still there, they are just labeled differently.

Fwiw I've found you want lots of fuel and not much timing to get a car to start well on e85 when it's freezing cold.

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10 hours ago, Sam said:

Have you played with both fuel and spark tables, or just the fuel tables? 

just fuel at this stage

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With the standard os I have adjusted auf0173, auf0181, auf0180. But for the custom os with flex fuel there is no blend map for auf0173, but there a few other lambda compensator table's.

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E85 will burn differently to what a gasoline fuel will, therefore I would suggest adjusting the the tables relating to cranking spark advance (auF0209 & auF1721). Those two tables along with the tables you have already adjusted should be able to get the car starting relatively well, there will be other tables you can adjust further refine that. But with those tables you should be able to get it starting well with the standard OS.

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Play with these

Commanded lambda at crank

auF0180

image.png.5ac36255a30cdd41aeca41ace910373d.png

auF0181 multiplier to cranking lambda. This is per PIP. A pip is an individual cylinder fire. Eg column 18 is after 18 cylinders have been fired from cranking. This effectively decays the commanded lambda from very lean to the actual commanded value.

image.png.2d3857b3df59e70e8d553cef785c0f20.png
 

Cranking spark advance auF0209 I've never tried modifying this one, but it makes sense to modify it as the flame burns slower with e85 beware of going too high as you can get detonation whilst cranking due to the very low rpm. Not the end of the world but best to avoid.

image.png.1a9d25128dc8dfe34e50a214f5e31c69.png

Then the base fuel table when the engine is cold auF0173. Make sure the bottom row is the same as the bottom row in your base fuel table.

image.png.0604509a2f878950fbd0dbc089f6e653.png

 

The numbers in the example above work ok as a base, but definitely need further tweaking. I have it starting first crank at 8°C in SA however at ~16°C it takes 2 goes, unsure if it needs more or less fuel as its been too warm to properly test. I will optimise it this winter and possibly do a proper write up then.

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4 hours ago, Sam said:

E85 will burn differently to what a gasoline fuel will, therefore I would suggest adjusting the the tables relating to cranking spark advance (auF0209 & auF1721). Those two tables along with the tables you have already adjusted should be able to get the car starting relatively well, there will be other tables you can adjust further refine that. But with those tables you should be able to get it starting well with the standard OS.

I did auf0209 this morning before I saw your post, dropped cranking from 10deg to 5deg, didn't really help.

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I would try increasing your spark advance instead of decreasing as E85 burns slower than what 98 would. 

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4 minutes ago, Sam said:

I would try increasing your spark advance instead of decreasing as E85 burns slower than what 98 would. 

haha ill try it the other way, iv heard conflicting things on timing for cold start with e85

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23 hours ago, [email protected] said:

Play with these

...

The numbers in the example above work ok as a base, but definitely need further tweaking. I have it starting first crank at 8°C in SA however at ~16°C it takes 2 goes, unsure if it needs more or less fuel as its been too warm to properly test. I will optimise it this winter and possibly do a proper write up then.

I have pretty much adjusted all those tables, it just felt like I was going way to far with them, eg to rich. Ill do some more testing, just sucks only getting a couple of shots at it per day

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@will15 as Puff suggest in colder climates lower spark advance may work better, however E85 likes more spark advance due to burning slower so lower spark advance for e85 may still mean higher spark advance than what 98 will require. I live in North Queensland so our winters only get to like 15 degrees so I haven't had much experience with cold starts in an actual cold environment. From memory my crank spark is 12 or 13 degrees and run up spark 14 or 15 degrees for e85.

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It's a fairly easy thing to check, providing that it's winter. I've halved the cranking spark from 10 to 5 on a different motor and it started better like that on e85, with 10:1 initial afr.

You'll get several goes at it if you don't mind getting up at 4 or 5am and trying every half an hour with just a 20 second run time. Bust out the garden hose to cool it off too if needed.

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1 hour ago, Puffwagon said:

It's a fairly easy thing to check, providing that it's winter. I've halved the cranking spark from 10 to 5 on a different motor and it started better like that on e85, with 10:1 initial afr.

You'll get several goes at it if you don't mind getting up at 4 or 5am and trying every half an hour with just a 20 second run time. Bust out the garden hose to cool it off too if needed.

haha now that's dedication, I think iv made some head way with this I have increased spark to 15 and upped the crank multi a shit tin and it busted off first crank this arvo. I will check in the morning and see how it is should get down to around 10deg tonight so see what happens. I did adjust the auf1721 and have noticed that with the flex fuel os there is no blend table, so will see how that go's when I finish tuning the other car on flex.

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So didn’t start first kick this morning but did on the second, so it is better. I think I’m missing a table that is stopping me commanding the afr I want but. Say you at 15 deg engine coolant and I have set 0.75 lambda, with in seconds of the engine starting it go’s straight to 1.0 lambda.

Is there some other table that could over ride all of the above fuel tables that have been discussed above?.

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Have you adjusted the cold base table? Also check that the open to closed loop delay is set for 30 seconds or more so it stays rich for long enough to warm up a bit without stalling.

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Yes adjusted cold base, it even dose it in open loop. I might extend the time for closed loop to enable though, it won’t hurt the situation.

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Set the open loop run timer to 60 seconds. I think it is only 10 by default. Once started it should idle fine at 1.0 lambda. It is just cranking that needs to be super rich, don't be afraid to make it 40% richer on cold start. Take a video of each start with the temperature and file it with the tune values you used, you'll quickly see if its improving or getting worse.

19 hours ago, will15 said:

I have pretty much adjusted all those tables, it just felt like I was going way to far with them, eg to rich. Ill do some more testing, just sucks only getting a couple of shots at it per day

Don't be afraid to go super rich, just keep track of how it starts vs your changes. E85 needs a lot more fuel. You could look at some GM tunes which do flex fuel from the factory and see what they do for a sanity check.

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I don't know why what im commanding is not working, iv made open loop longer but 3 seconds after the car starts its commanding 1.03 with engine temp at 10 deg (in open loop). The engine wants more fuel and I can't give it to it.  I have posted a tune if anyone would like to check it out.

e85 finished.tec better starting.tec

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@will15 I noticed on auF0181 that the table has been modified massively and has some very large numbers everywhere. I would suggest returning that to stock and having another look at it, or looking at Roland's table that he posted on thursday.

Pip.thumb.png.49ac55feff80347a73cd5f788b6f5298.png

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5 hours ago, [email protected] said:

Yeah that will make it lean during cranking for sure

So smaller numbers is richer?, I was thinking the other way. I don’t really understand your  explanation of how the table decays form commanded lambda from very lean to the actual commanded lambda

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I just tried that pip crank table as stock, the car has not been started today with 17deg  ambient temperature and it took like 5 go’s for it to start. It was starting first kick with the high numbers in that table at 17 ambient temp

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image.png.d410c1dc297bf7587c7f4787fbd443ca.png

image.png.95230d6cf6c3c0194edb683eb9849892.png

If the engine speed is under auF11086 (crank rpm) and the throttle is below auF11922 (TPS counts) then it is considered in stall mode and activates "crank mode"

In crank mode it uses auF0181 "Multiplier to cranking lambda to taper the cranking fuel"

the final commanded AFR is as follows:

Commanded_Lambda = auF0181 / (base_fuel_cold - lost_fuel)

So in a stock car it tapers from 1.8 to 0.8 when cold. When warm it tapers from 1.1 to 0.7

Lets say we are commanding 0.8 lambda in the base fuel (auF0173) and have 0.085 lambda lost (auF0178)

at 0 pips Commanded_Lambda = 1.8 / (0.8-0.085) = 2.5 lambda

at 720 pips Commanded_Lambda = 0.7 / (0.8-0.085) = 0.97 lambda

So a lower number is going to result in a richer start. I don't really understand how having a huge number like 3 or 4 would have even started at all? 

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On 4/13/2019 at 1:18 PM, Puffwagon said:

Try doing this below, or a variation thereof.

 

QstuHNs.jpg

This table definitely makes a big difference in commanded lambda, helps stop the stalling when cold and you put the can in drive or reverse. 

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1 minute ago, will15 said:

This table definitely makes a big difference in commanded lambda, helps stop the stalling when cold and you put the can in drive or reverse. 

Yep that table and the cranking PIP table are the ones you want to play with. You can achieve the same thing with the base fuel when cold fuel table as well.

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I’m  getting it a lot better, but the only way it works is to use the PIP table backwards then what you guys have said.  Say the PIP table is stock and I log cold start inj timing will be say 10ms, then I half the valve in the PIP table inj timing will be 5ms. So then I double stock value it will be 20ms. It seems to work well so I don’t know. Then only other problem is about 40 seconds in to a drive after cold start it will command 1.20 lambda and stumble.

I have gone though every table I can think of and it still dose it.

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2 hours ago, [email protected] said:

When does it command 1.2 lambda? There should be a hard limit at 1.05 lambda.

I’m tuning to cars at the moment and they both do it about 30sec to I minute from cold start around 23 deg coolant temp.

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Yes it is commanded afr not wide band, I don’t have a wide band in the car at the moment. But I can see the narrow band o2 go lean when the ecu commands this and the car will stumble and nilly stall when I’m driving up the road at about 40km. I can get a lot of it happening but I’m using hp tuners for the logging.

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When’s the e85 cold start thread how to coming?, because this cold start tuning is really starting to pee me off.

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1 hour ago, will15 said:

When’s the e85 cold start thread how to coming?, because this cold start tuning is really starting to pee me off.

Pretty much everything you need to know is in here already. But one day when I get time I will go over it in depth. First I want the datalogger finished as that will be crucial to logging lambda vs the various scalars.

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with auf11086 being set at 190rpm (stock) I would think it would come out of crank mode while cranking, I have not had a chance to look at cranking speed just yet but im sure it would have to be quicker then 190rpm. Any one tried playing with this?

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