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Discussion Starter #1
Okay, so I just bought hptuners and I'm currently comparing my custom tune from my tuner to the stock gto tune in the samples to see what changes my tuner made. I noticed in the cranking spark table, my tuner didn't make any changes.
Most of the time I cold start my car when it's around 70 degrees or colder out, the car takes 2 cranks to start. I Understand e85 doesn't like cold starts, but I don't think it should matter at 70 degrees. Does anyone think modifying this table at all would help with cold starts?

As a reference, here is the stock/my cranking spark table
504589


504590

Also, here is a cranking spark table posted my someone on hptuners with the same year of gto, e85 but different mods who claims they never have a issue cold starting the first crank, whether it be e85 or 93.
 

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I tried messing with the crank spark and crank fueling tables in the past to try to get better starts on e85, and eventually just had to admit to myself that it's over my head for the the time being.

I would also like to know what settings will result in better starts for e85 in cold weather.

I think it can also depend on the blend of e85. Yes it can measure out to 83% ethanol, but what gas do they use? I think it definitely matters.

I have had no issues on occasion in cold weather, and sometimes it takes a few extra cranks and then starts. My red car has higher compression, so that may help. I typically have no issues starting my red car in colder weather, but my blue car can have an extended crank time. I've switched back to gas on my blue car recently, anyway... i couldn't justify the poor mileage on a car that isn't anywhere near max effort
 

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Discussion Starter #3
Also, I don't know if it makes much of a difference, but looks like he also made changes to the startup Flare Cont. table. The table on the right is my current tune and the table on the left is the stock tune.

504591
 

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Discussion Starter #5
I tried messing with the crank spark and crank fueling tables in the past to try to get better starts on e85, and eventually just had to admit to myself that it's over my head for the the time being.

I would also like to know what settings will result in better starts for e85 in cold weather.

I think it can also depend on the blend of e85. Yes it can measure out to 83% ethanol, but what gas do they use? I think it definitely matters.
I've tested the e85 from the two gas stations I buy from several times throughout the year and it always comes out to 85% ethanol. I live in Texas so we don't usually have very cold winters.
e85 cold start problem
Here, is the link I came across where a fellow gto owner posted that table who claims he has no starting issues with e85.
 

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Hmmn. I saw a mention of someone saying different areas matter.

I think that the gas uses definitely matters. Ethanol is ethanol, unless it is tainted with something other than the small amount of gasoline they use to denature it. Gas is a blend of several different hydrocarbons and additives, so it is feasible some places mix with cheap crap just to make a buck.

Either way, combustion chamber temp will matter with ethanol. It doesn't like the cold. I mean, maybe a block heater will help, LOL.

Lakegoat is a pretty reputable member, i haven't seen him post in a while.
 

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Discussion Starter #8
While I have your attention Nothubertjfarnsworth, do you know where you would modify spark for e85? I was looking at my tune, and I noticed under spark advance, my tuner has the flex fuel, gas, Alcohol tables all blanked out. I remember when he was tuning it, the car made the same amount of power on e85 as 93 at first. He was about to give up but then he tried something else and then it gained 50whp. I wonder if he did it correctly or not.
ls1gto won't let me attach my hpt file but I just recently posted it on ls1tech in this thread, Just received hptuners, can anyone Take a look at my custom tune? - LS1TECH - Camaro and Firebird Forum Discussion
Thanks.
 

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do you have a flex fuel sensor hooked up?

i'll take a look at it. my memory usually fails me and i don't remember all the tables.

FWIW my tables are pretty similar to the tables i had on gasoline.
 

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You're on the wrong track. Your issue is the initial fuel prime with E85. I don't have a check valve either which adds to it. If I turn the key on and let the pump prime for 2 seconds then bump the starter not even one full revolution then turn the key back off. Then turn the key on and start it the engine pops right off immediately in everything from zero degree weather to 100 degree weather. I personally have never cared to worry about it and just live with it since having no check valve is always going to take more to prime anyway.

If you really care to fix this issue it's with the initial prime not the spark. E85 takes more fuel which everyone knows, but they don't change the prime time of the pump, initial prime pulse mass of the injectors, or cranking VE. My issue is the lack of a check valve so I don't get to upset about it and just give it extra time with the key on to prime, but if you really want to work on cold starts look at your prime pulse, cranking ve, etc.
 

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Going to look that up later, haven't had the chance to look with hptuners yet.

I think the tables 05silgto is talking about are multipliers. Which might be ok, it just uses the same settings with e85 as with gas. Not sure how they are used by the ECM since, if they are the tables i am thinking about, i have never changed them. Maybe the ECM proportially baises towards the multiplier depending on alcohol percentage. I should probably dig around hptuners.com for more info. I don't use a flex sensor, unfortunately, so i wouldn't be much help there. Yeah, i know, lol. I should on my 05, I can't on the 04...

As far as priming and crank VE, i remember having played with cranking fuel before on my 04, and I think i have increased the prime duration as well. Both really produced no improvement in cranking time, although my only real issue was starting in colder weather. For cold starting, i honestly think all you can do is use a little more gas in the blend to help you start the car.

If it is a staring issue regardless of ambient temp, i would stick with tuning.
 

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People like to do things differently I will not argue. I've tuned cars that don't have start up issues in below freezing temps. The only E85 cars I've tuned that have cold weather starting problems are like mine with no check valve in the fuel system to hold pressure in the lines. The p59 is hard coded at 2 seconds prime time with the key on which is the reason I turn the key on let it prime then back off and on again it will pop off immediately. Some times people do work around rig jobs with other things that make their cold starts better and assume it is the answer. If the tune is good and everything else is correct then cold starts aren't an issue with e85 down to zero degrees. I only get a week or so a year below that temp and usually everything is iced up anyway so the GTO isn't coming out of the garage.

Have a great day guys! It's a beautiful one think I'll go to Mexico for a bit...LOL.
 

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I got distracted during the middle of an edit, so i dunno what you saw LOL.

might be the last really nice day we have here for some months. Have fun.
 

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Just looked at hptuners. The flex fuel/gas/alcohol tables just look like adders to the main spark. There is a table that modifies WOT spark for varying alcohol percentages as well. I doubt any of these tables would affect cranking spark.

Cranking VE in the LS2 tune is all 100's, which makes me wonder how the cal uses that table.

The LS1 tune looks like it uses it, but it looks like it's not something that i have messed with. I was thinking of the FA vs crank time table. A quick search found some stuff on hptuners originally posted by redhardsupra, but it doesn't look like the spreadsheet to properly calculate the values is still available.


Hadagto was right on the money with the hard coding for the 04 ECM. Tables for pump prime duration and duty cycle weren't even available for the 04. Which is weird, because I swear i can remember messing with it. Might have been on my red car then, but for another reason... eh that's what happens when you own this crap for so long and don't work with it every day.

He's also really on to something about the priming pulse. Gotta look more into that one. Maybe OP can ask his tuner. Doesn't really look to be available in the LS2 tune, although the priming duration is editable.
 

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Discussion Starter #16
Thanks for the help guys. Not sure if prime duration will help, cause I have a fuel pressure gauge and I always remember seeing 58psi before cranking. I looked through hptuners anf found this under engine-fuel-cranking fuel, "[ECM] 12320 - Cranking FA Mult Stage 1 vs. Cranking Time: These tables are FA multipliers that determine fuel delivery in relation to time."
These values look the same compared to stock, maybe I can increase the values in the 70 degree range slightly.
E85 Versus Gasoline
Properties
................ Ethyl Alcohol.......Gasoline
Boiling Point
.................173° F...............102° F
Solubility......................Miscible..............Insoluble
Flash Point........................55° F.........-45° F
Upper Explosive Limit......19%.............7.60%
Lower Explosive Limit.......3.30%.........1.40%
Visible Flame....................Yes...............Yes
With the flash point of e85 being 55F you would think I shouldn't have any starting issues at 70 degrees.
 

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Mexico went well a few wide open throttle pulls logging the new procharger pulley change that has me spinning the blower slightly beyond it's recommended limit...LOL. This guy can explain it better... I want to stress that he is using a completely different ECU, but it doesn't matter at all. As a tuner you need to learn how an engine works and what it wants instead of focusing just on your specific ECU or software. Once you understand how to determine what an engine wants all you have to do is find where it is on your particular ECU/software to make the needed adjustments. OK now once you can get beyond needing your hand held to show exactly which tables and work through the menu's on your own this video will make sense. Teach a man to fish vs giving him a fish as they say... Anyway here is a good video the terms are the same the ECU is different, but you should be able to figure that out...

 

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Thanks for the help guys. Not sure if prime duration will help, cause I have a fuel pressure gauge and I always remember seeing 58psi before cranking. I looked through hptuners anf found this under engine-fuel-cranking fuel, "[ECM] 12320 - Cranking FA Mult Stage 1 vs. Cranking Time: These tables are FA multipliers that determine fuel delivery in relation to time."
These values look the same compared to stock, maybe I can increase the values in the 70 degree range slightly.
E85 Versus Gasoline
Properties
................ Ethyl Alcohol.......Gasoline
Boiling Point
.................173° F...............102° F
Solubility......................Miscible..............Insoluble
Flash Point........................55° F.........-45° F
Upper Explosive Limit......19%.............7.60%
Lower Explosive Limit.......3.30%.........1.40%
Visible Flame....................Yes...............Yes
With the flash point of e85 being 55F you would think I shouldn't have any starting issues at 70 degrees.
It's the amount of fuel you need when priming and cranking the engine. Everyone that tunes compensates for the extra fuel requirements of ethanol, but often don't get the startup fuel requirements correct. Also if it was tuned in warmer weather the start up air flow and mostly the base idle airflow at colder temps may not be enough. I'm not going to hold your hand through this anymore, but leave this last bit of advice...log your base running airflow from a cold start on the coldest morning to make sure those air flows at lower temps are correct in the tune...work with and understand the initial prime mass, other priming tables and cranking VE tables.
 

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Discussion Starter #19
It was tuned in colder weather, probably around 50 degrees which is cold for us. Thanks for your help, I'll start logging soon when I put the car back together. I'm doing a bit of maintenance right now.
 

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Mexico went well a few wide open throttle pulls logging the new procharger pulley change that has me spinning the blower slightly beyond it's recommended limit...LOL. This guy can explain it better... I want to stress that he is using a completely different ECU, but it doesn't matter at all. As a tuner you need to learn how an engine works and what it wants instead of focusing just on your specific ECU or software. Once you understand how to determine what an engine wants all you have to do is find where it is on your particular ECU/software to make the needed adjustments. OK now once you can get beyond needing your hand held to show exactly which tables and work through the menu's on your own this video will make sense. Teach a man to fish vs giving him a fish as they say... Anyway here is a good video the terms are the same the ECU is different, but you should be able to figure that out...

thanks for that, i will give it a watch.
 
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