2010 Sierra hard to start when cold (not freezing just cool)

nealinator · Dec 18, 2017

I have been having increasing problems with my truck acting like it does not want to start in the mornings. The problems have gotten worse since colder weather has come in here in south TX. Mind you it is not really severe cold....just in the 50's and some 40's. It only acts up when the truck has sat long enough to be cool....8+ hrs. After it is warmed up or has only been sitting a short while since it has run ( an hour or two even up to 4 or 5 hrs)...it cranks just fine with no issues.

I found this old thread which has some similar acting issues...but not completely the same.

2010 LT hard to start when cold, have to give it some gas.

I have no codes at all...not any CEL at all.

The engine will try and turn over and it just does not "catch" sometimes takes a few seconds then will start. Yesterday, it took three attempts to crank it. Getting a bit nervous and really need to track this down.

The idle has been seeming a bit more rough than it had been...and part of me had been suspecting that the TB needed cleaning. Well this weekend, I was going to clean it and when I got the duct work off...it looked ok. A little bit of discolored buildup...but nothing like when I first cleaned it after buying it with 92k on it and was not worth my time to mess with it.

Several on that old thread mentioned about a computer re-flash or something due to it reading higher alcohol content in the fuel than it really was. Is this something I can do by just unhooking the battery for a while?

Any thoughts or input would be greatly appreciated. I have 139,400+ miles right now...a 87 octane Diablosport tune on it. Other than that...stock.

I have not checked the plugs...but brand new AC Delco Iridium ones were put on about 2 years ago. New wires too. But if there were spark issues I would think I would be getting a misfire code.

apcnc · Dec 18, 2017

Have you checked the alcohol content?

nealinator · Dec 18, 2017

Ah...and I did get the battery check yesterday although I did not sense any weakness at all. It turns over the engine fine and not lugging...it is just that the engine does not "catch". Baffled why there would be no code.

The reason I had the battery tested is that when I was doing some stuff on it I had the door open for a bit and got a warning of low battery in the DIC to crank the engine. I had only seen that before when my old battery was going out. I have a fairly new battery...3 or 4 months old I think.

nealinator · Dec 18, 2017

apcnc said:
Have you checked the alcohol content?

No. I think someone said the other day it can be seen using the Torque app. But I have not looked at that.

What should it be....and if it is not reading correctly...what can be done about that?

apcnc · Dec 18, 2017

It should be less than 10%. It sounds like it has got a higher reading which would cause your problem. Just need to check and see if its high. If so usually a tank of 100% gas and a good drive at 60-70 mph for 10 min or so will do the job.

nealinator · Dec 18, 2017

I dont think anyone around here has 100% gas...where does one find that?

apcnc · Dec 18, 2017

Hi-tech Fuels does.. I think some cowboys do. Ive seen some others but don't recall right off.
Here is a link and probably some other services as well.
https://www.pure-gas.org/index.jsp?stateprov=TX

nealinator · Dec 18, 2017

Went out and played with torque app. Could not fine alcohol content anywhere.

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apcnc · Dec 18, 2017

You have to create it. PID 52. Didn't want to read though in the torque app. You diablo should read it though I believe. If not try elm terminal. You can manually input requests. Just connect it and type 012552 and enter. It will come back with 4152XX. The digits after 4152 is your content. But is data from one byte 0-255. Take that number and divide by 255. That is your percentage. It is Hex also. If you not familiar with HEX. It is 0-F or 16 base. instead of 10. So after 9 you have A which is 10 B-11 c-13 etc. So 2E would be 2*15+14=44 44/255=0.1725 or 17.25%

nealinator · Dec 18, 2017

I have no idea what all that means....lol!

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diy_darryl · Dec 18, 2017

Neal, you can look up a Hexadecimal to Decimal converter online.

But to avoid confusion, we should correct the math in the above example. Sorry, no clue how to type exponents.

2E=2x16(to the 1st power)+14x16(to the 0 power)=2x16+14=46

nealinator · Dec 18, 2017

I can figure out hexidecimal....But have no idea how to access the section of the torque app noted or what in the world elm terminal is.

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diy_darryl · Dec 18, 2017

Okay, I thought you probably could being an engineer but maybe civil engineers or some other types do not go into that territory??? LOL

I misunderstood but the math in the example still needed correction to avoid confusion for others.

apcnc · Dec 18, 2017

Elm terminal is another app. Not associated with the torque app.

Lol sorry for the math confusion its not meant to be complicated just a quick explanation. There is no exponents. The number in the second position from the right is in the 16s. What we would call the tens position in base ten. Just multiply that number by 16 and add the one on the right.

redtherocket · Dec 18, 2017

Ethanol.... You have to much..

Or... You have gel'd gas in your tank...

I would run your truck down to the las1/8 tank and add a can of Seafoam.. Marine and fleet... Sounds hillbilly... But it works... Then lock out4th and drive it until you think you are absolutely out of gas... Like carry a can of gas with out out...lol

Then take the hit and fill with ethanol free premium.. Shell.

This has worked for me and my dad for this same reason. 2010 and 2013 Sierra..

Godd luck Neal.

apcnc · Dec 18, 2017

In the torque app go to settings... Then other settings. Under advanced got to manage available pids. In the top right use the menu and choose add custom PID. OBD PID would be "0152" for mode 1 pid 52. Or "012552" GM PIDs. Either should work with the truck. Not sure if this works on the torque app... It did not at one time but new ver may.

Equation would be (A/255)*100 for percentage.

Did you try the Diablo? I thought it was setup to read it.

nealinator · Dec 18, 2017

Thanks for the replies.

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zbkeebler · Dec 18, 2017

Neal, Do you have the pro version of the torque app or just the lite? the pro version I think is what gives you access to all the sensors on the computer. You'll then just need to dig through and find the list that has all the fuel trims listed and misfire counts and temperatures. tons of good stuff for diagnosing what's going on. I'll try and hook mine up and tell you exactly what to click on if you don't figure it out on your own first. I haven't been using it much since I got my innova 3160e

nealinator · Dec 18, 2017

Just the free one for now. I figured if I used it then I would upgrade...but never did use it much. Probably not much of a charge so I may get the Pro and check things out.

Thanks.

nealinator · Dec 18, 2017

redtherocket said:
Ethanol.... You have to much..

Or... You have gel'd gas in your tank...

I would run your truck down to the las1/8 tank and add a can of Seafoam.. Marine and fleet... Sounds hillbilly... But it works... Then lock out4th and drive it until you think you are absolutely out of gas... Like carry a can of gas with out out...lol

Then take the hit and fill with ethanol free premium.. Shell.

This has worked for me and my dad for this same reason. 2010 and 2013 Sierra..

Godd luck Neal.

Just curious if it is a fuel issue...will it go back to acting messed up when I go back to the same fuel? I have been going to Exxon and before that Shell presuming I would be getting decent fuel. I do buy the 87 octane only.

diy_darryl · Dec 18, 2017

Well, I beg to differ, there are exponents in the calculations. If you had another digit, say in the 'Hundreds' slot in base 10, that would be multiplied by 16 to the 2nd power or 256, your '10's' digit in your example is 16 to the 1st power or just 16.

I was only correcting the example to begin with because they were multiplying by 15 instead of 16.

nealinator · Dec 18, 2017

This does not help me fellas...take it to the math forums....lol!

apcnc · Dec 18, 2017

That's right. What I'm saying is there are no exponents needed this calculation. Trying to keep it simplified as much as possible. Max value is 255. So there will never be a third place. Second place is just 16*X. Power of one is the same and not necessary. Yeah I saw I had 15 :lol: I starting a new base 15! good catch.

Apparently Ive failed simplifying this :lol: If you get a response and dont understand it post it.

diy_darryl · Dec 18, 2017

Sorry Neal, LOL!!!!

I guess we de-railed you, go with the common consensus and get some ethanol out of there......maybe???

But....I am interested in bi-directional testers/scanners such as Tech II clones or something else so this is informative.

redtherocket · Dec 18, 2017

Since you say this happens in the cold you probably have gas that is switched over to winter gas in your area

They butane to gas for winter and the tanks sometimes get additives added to remove moisture for the season

This could be the side effects of a shitty gas station bud.

nealinator · Dec 18, 2017

Yeah...I was wondering if there could be something in play with the winter blend...but had not considered things they do at a station. Again...would think that an Exxon would be run well and have no issues. I will switch for a bit and see how it goes once I drain this tank.

2010 Sierra hard to start when cold (not freezing just cool)

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