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Gone lean overnight, wtf

This is a discussion on Gone lean overnight, wtf within the Nitrous forums, part of the LSx Technical Help Section category; I monitor air/fuel ratio and fuel pressure, overnight my nos kit that i had dialed in during the winter months ...

  1. #1
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    Gone lean overnight, wtf

    I monitor air/fuel ratio and fuel pressure, overnight my nos kit that i had dialed in during the winter months at 12:1 stoich, has jumped to 16:1. I checked fuel solenoid, functions well with no clogged jets. No changes to fuel pressure from my winter dial in. Did the refiners increase the ethanol content of the fuel, or what? Local gas pump claims to be up to E10. On motor there has been no change to the stoich. This is my first change of seasons since the monitoring began so maybe a veteran can share some insight.
    Last edited by LS1 Formula; 06-16-2013 at 10:20 AM.

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    Member goof4080's Avatar
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    I'm by no means an expert on the matter but the difference in air density between winter and summer might be big enough for that change. Also does your area have a summer fuel mixture? Maybe both are contributing factors.

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    I think my area does due to the pollution problems we have each summer. I'm pretty sure my state is after that fed money but i will need to due some research to verify. I know that may/june are usually the months to switch to these summer blends. As far as the density of air, i would think the stoich would go the other way in this scenario but i too am no expert. thanks for the response. Either way its time to dial in the kit again but it caught me by surprise and was wondering if this is typical for changing seasons.

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    Moderator Firebirdjones's Avatar
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    It's time for summer blend gas, and I notice changes in AFR with it. I also see changes in AFR from one pump to the next because ethanol isn't consistent from one station to the next.

    Ethanol test kits are all over the internet fairly cheap if interested. I've found as much as 17% ethanol at pumps that advertise 10%, so you can't always trust what you read. Might want a test kit just to check what's in your tank and rule out that variable. Doesn't take much ethanol to make a difference in AFR. What you are seeing is a pretty big swing in AFR though. Just a 10% increase in ethanol is about a .8 AFR change roughly. You are seeing 4 full points, so you might have something else going on or a combination of things.

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    Thank you FirebirdJones,
    I have read alot about summer blend fuels this afternoon. I too am concerned by the large percentage jump and considering the rough estimates you provided of 10% = .8. I will definitely investigate more than just a fuel issue, but i do see an ethanol test kit finding a place in my toolbox in the near future.

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    Hey FirebirdJones or anyone else,
    I just performed a test on the fuel in my tank. It may not be the most accurate but i think due to the test volume size it accurate enough to differentiate the E50-E60 that would be needed for a 4pt. delta move from E10.

    Observation of fuel is clear so water contamination of fuel in tank ruled out.
    1/4 cup water and 3/4 cup fuel in a Kerr bottle.
    Measured heights pre and post mix and come up with around E10.

    My oil looks good and clear.
    My coolant level looks good and the coolant doesn't look contaminated.

    However this afr issue on the kit literally just started Saturday morning after a rough night of driving it like i stole it on Friday night. But the car felt a little weak from what i am used to and i was preoccupied so couldn't tell you what the afr was.

    I recall reading earlier today that water contaminated fuel drops octane and is referred to as "lean fuel".

    I have deleted the coolant line running to the throttle body years ago so cracked throttle body is out of the question.

    I'm thinking I may be building too much cylinder pressure and lifting a head or heads on the kit allowing coolant to weep into the cylinders.
    Or i have a head gasket/s that may have been compromised but not enough run time to show contamination.

    Its a low compression LQ4 with a decent cam, 150 shot.
    Stock head bolts, stock head gaskets...

    Anyone want to share what a spark plug would look like if this were the case, i will check them out tomorrow.
    Last edited by LS1 Formula; 06-17-2013 at 01:44 AM.

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    Veteran 0rion's Avatar
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    my rule of thumb for these things is to start simple.....fuel filter first. What are your afr's at idle and cruising around? Are you only noticing the lean issue during WOT runs? What's your LTFT's in the cells prior to going WOT and are you only lean on the spray?

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    Moderator Firebirdjones's Avatar
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    Orion will get you on the right track.

    Here are some notes of mine for anyone interested in seeing how this ethanol affects AFR's.

    Stoich for gas 14.7:1
    E10 - 14:1
    E15 - 13.8:1
    E85 - 9.7:1

    You can see why gas mileage is affected. With the wild swing in ethanol that I've seen at the pump (as much as 7 points from advertised) you can see how it would affect your target AFR. Rather than tune on razors edge anymore, I tend to nowadays just tune for a safe AFR so I don't have to worry so much about what I might get at the pump. I may be a little rich under WOT and I do leave a black mist which leaves some HP on the table, but with crappy fuels now I prefer to keep the equipment safe. If you really want to throw a curve ball in there, I also have to compensate for altitude changes in my case since I live 5,000 ft up and travel to see level regularly so it complicates things even more.

    But this is another subject all together.

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    Quote Originally Posted by Firebirdjones View Post
    Orion will get you on the right track.

    Here are some notes of mine for anyone interested in seeing how this ethanol affects AFR's.

    Stoich for gas 14.7:1
    E10 - 14:1
    E15 - 13.8:1
    E85 - 9.7:1

    You can see why gas mileage is affected. With the wild swing in ethanol that I've seen at the pump (as much as 7 points from advertised) you can see how it would affect your target AFR. Rather than tune on razors edge anymore, I tend to nowadays just tune for a safe AFR so I don't have to worry so much about what I might get at the pump. I may be a little rich under WOT and I do leave a black mist which leaves some HP on the table, but with crappy fuels now I prefer to keep the equipment safe. If you really want to throw a curve ball in there, I also have to compensate for altitude changes in my case since I live 5,000 ft up and travel to see level regularly so it complicates things even more.

    But this is another subject all together.
    I would think out there you guys wouldn't have the problem with winter/summer blends that we do out here or at least be able to drive down the mountain to some place that doesn't use a winter blend. What I do is don't drive the car during the winter so it's never an issue. I really don't think that's his problem here but stranger shit has happened I guess. 4:1 is a huge swing.....I'm curious as to what his afr and trims look like in all conditions. Stock fuel pump? What brand fuel solenoid? ect ect. I have way more questions than answers.

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    Veteran 0rion's Avatar
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    Quote Originally Posted by LS1 Formula View Post
    Hey FirebirdJones or anyone else,
    I just performed a test on the fuel in my tank. It may not be the most accurate but i think due to the test volume size it accurate enough to differentiate the E50-E60 that would be needed for a 4pt. delta move from E10.

    Observation of fuel is clear so water contamination of fuel in tank ruled out.
    1/4 cup water and 3/4 cup fuel in a Kerr bottle.
    Measured heights pre and post mix and come up with around E10.

    My oil looks good and clear.
    My coolant level looks good and the coolant doesn't look contaminated.

    However this afr issue on the kit literally just started Saturday morning after a rough night of driving it like i stole it on Friday night. But the car felt a little weak from what i am used to and i was preoccupied so couldn't tell you what the afr was.

    I recall reading earlier today that water contaminated fuel drops octane and is referred to as "lean fuel".

    I have deleted the coolant line running to the throttle body years ago so cracked throttle body is out of the question.

    I'm thinking I may be building too much cylinder pressure and lifting a head or heads on the kit allowing coolant to weep into the cylinders.
    Or i have a head gasket/s that may have been compromised but not enough run time to show contamination.

    Its a low compression LQ4 with a decent cam, 150 shot.
    Stock head bolts, stock head gaskets...

    Anyone want to share what a spark plug would look like if this were the case, i will check them out tomorrow.
    just re-read the thread.....are you on the stock fuel pump? I bet you're running out of fuel if you are. Jet it to 100 and see what happens. You have to be right at the limits of the stock pump.

  11. #11
    Moderator Firebirdjones's Avatar
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    Quote Originally Posted by 0rion View Post
    I would think out there you guys wouldn't have the problem with winter/summer blends that we do out here or at least be able to drive down the mountain to some place that doesn't use a winter blend. What I do is don't drive the car during the winter so it's never an issue. I really don't think that's his problem here but stranger shit has happened I guess. 4:1 is a huge swing.....I'm curious as to what his afr and trims look like in all conditions. Stock fuel pump? What brand fuel solenoid? ect ect. I have way more questions than answers.
    Yeah I agree 4:1 is a big swing, I don't think it's the fuel either, I just tossed out some helpfull tuning notes that I keep in mind.

    You are right, winter blend isn't an issue in the Phoenix metro area, and I don't suspect it's an issue where I live in Prescott Valley because it's not really that cold here either, but possibly up in Prescott where the elevation is slightly higher (colder) there may be some winter blends up there, but I don't gas up there myself.
    Flagstaff however I'd bet has winter blends at 7,000+ feet elevation it gets damn cold up there, I don't go up there

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    Idle 14.5:1 at operating temp.
    Cruising between high 13's:1 to high 14's:1 (bounces around a bit)
    On motor only at wot 12.5:1, fuel pressure at 58psi
    On the kit 16:1 immediately, wot micro switch, fuel press drops to 52 psi. (255 in the tank)

    I cant answer the fuel trim question, paid for the programming. If memory serves me well the programmer pulled 4degrees off total advance for a 100 shot of spray. Well known programmer for the southwest, tuned in the winter 40 deg dry air.
    I will add.
    I'm equipped with a pressure activated bottle warmer, winter passes usually held around 950 psi.I had to increase nitrous jets from suggested (fuel 100 jets/nos 150 jets) to pull me out of 10:1 up to 12:1.

    Air is now 95 deg dry air.
    These lean passes have had 1150 psi and i have increased the fuel jets to sync with the nitrous jets previously described, next plan of action was to decrease the nitrous side providing no mechanical issues. And as you suggested, change the fuel filter. I dont know that i ever have now that i think of it, 130,000 miles on car, doh!

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    What I have read about az winter/summer blends is.
    RVP 9.0 winter blend.
    RVP 7.0 summer blend to avoid the VOC's from evaporation.
    Looks like the drop the butane content from 10% to 2% and fill that void with whatever cheap crap they can.

    It's a TNT kit.

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    Where are my manners, Thank you two for trying to help me out. Left to my own devices I will rebuild the whole damn car! lol

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    Moderator Firebirdjones's Avatar
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    Did Nic tune the car?

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    yes

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    The running out of fuel is a serious possibility. I changed the pump and rigged it inside the stock plastic cylinder. First time i let the car get to 1/4 tank it ran out of fuel on motor wot. I dreaded tearing back into that tank, I'm a shadetree mech, so I have just kept the tank topped off when I'm playing.

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    Moderator Firebirdjones's Avatar
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    I'm sure the tune isn't an issue then.

    I think Orion is on the right track.

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    I feel the same way, the car has been fed 60 lbs on nitrous up to this point. A lot of big power stuff is sent his way, and my build is a typical run of the mill. I didn't mention his name cause I dont know forum etiquette.

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    Quote Originally Posted by LS1 Formula View Post
    Idle 14.5:1 at operating temp.
    Cruising between high 13's:1 to high 14's:1 (bounces around a bit)
    On motor only at wot 12.5:1, fuel pressure at 58psi
    On the kit 16:1 immediately, wot micro switch, fuel press drops to 52 psi. (255 in the tank)

    And as you suggested, change the fuel filter. I dont know that i ever have now that i think of it, 130,000 miles on car, doh!
    I quoted the important items I feel are an issue for Orion to comment on. Interested to see how this turns out.

    As far as bad gasoline is concerned, is using methanol as a supplement ever suggested for running nitrous? I never read up on nitrous much, but I'm using a AlkyControl kit myself with my SC, which I read and was informed by my tuner, gives me a lot more lee-way from something like this affecting anything. Or, is Nitrous already working like such?

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