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Discussion Starter · #1 ·
Alright so I deleted my LMM dpf and egr just about a year ago with EFIlive and Sinister blocker plates. But just recently the high idle has stopped working everytime under 32 degrees F. I did the whole thing with holding the gas pedal and tapping the brake 3 times. It'll high idle sometimes but in the morning when it's under 15 degrees it won't high idle at all. So I don't know what it is. Anyone have any ideas? :help
 

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I have the same mods with the same issue. Mine will even high idle when it is above 32 degrees sometimes. Interested to see if anyone has an answer for this.
 

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Discussion Starter · #3 ·
I have the same mods with the same issue. Mine will even high idle when it is above 32 degrees sometimes. Interested to see if anyone has an answer for this.
It's so annoying dude. How do you like your FASS system? I've been thinking about doing it. Definitely noticeable in performance and fuel efficiency right?
 

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It's so annoying dude. How do you like your FASS system? I've been thinking about doing it. Definitely noticeable in performance and fuel efficiency right?

Not sure yet I don't have it all hooked up. It's been way too cold here to work on it and I bought a sump so I'm waiting for the weather to get warm and my fuel tank to get empty at the same time lol.
 

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Did both of you loose high idle as soon as you flashed your tunes or was it some time afterwards? Have you scanned the truck for trouble codes?
Generally an LMM high idle will kick on a few minutes after starting the truck (once oil pressure comes up it will kick on) and they should run until coolant temp comes up. I cannot remember the exact numbers off the top of my head.
 

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It's so annoying dude. How do you like your FASS system? I've been thinking about doing it. Definitely noticeable in performance and fuel efficiency right?
I feel a lift pump is needed when you add bigger HP, so you'll pretty much always have fuel at the engine and not stall, when under heavy load, or racing.
I'm running AirDog with only a 40hp tow tune.
As far as "Definitely noticeable performance and fuel efficiency", NO.
At least for my truck, NO, Nada, Nothing that resembles what your asking.
Except for the stalling part under heavy load or racing with adding big hp, otherwise with normal driving NO.
 

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Did both of you loose high idle as soon as you flashed your tunes or was it some time afterwards? Have you scanned the truck for trouble codes?
Generally an LMM high idle will kick on a few minutes after starting the truck (once oil pressure comes up it will kick on) and they should run until coolant temp comes up. I cannot remember the exact numbers off the top of my head.

I flashed my truck back in the summer so I'm not 100% sure EFI live is the cause of it. But sometimes when it's really cold I can let my truck idle for 15 mins and high idle won't kick on. Then if I drive 5 miles and stop put the truck in park it'll kick on instantly.
 

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Did both of you loose high idle as soon as you flashed your tunes or was it some time afterwards? Have you scanned the truck for trouble codes?
Generally an LMM high idle will kick on a few minutes after starting the truck (once oil pressure comes up it will kick on) and they should run until coolant temp comes up. I cannot remember the exact numbers off the top of my head.

Forgot to mention yes I have scanned for DTCs and I don't have any. Only lights I have on are the stabilitrac and TPMS lights.
 

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Correct me if i am wrong? " hit the brake pedal 3 times"? I thought it was the gas pedal when key is on but not running. Or is that just for the oil reset ? :drink
 

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Correct me if i am wrong? " hit the brake pedal 3 times"? I thought it was the gas pedal when key is on but not running. Or is that just for the oil reset ? :drink

Fuel pedal to the floor and hold it there. Tap the brake 3 times as quick as possible and that should turn it on or off.
 

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Are you running a winter front on your truck? I never used to run mine on my LML. Never needed it. Once I deleted and installed my tunes, my truck started running way cooler. So I put my winter front on. Now it barely ever goes into high idle unless it's really cold. Reason being...... the winter front holds the warm air from the engine in. So all of the air temp sensors are getting incorrect readings. When I pull up and park at -15, the warm air under the hood makes the truck think it's a lot warmer than it is. So when I start the truck the next time everything is wickity wack. It would be nice if there was some sort of fix for it seeing as the winter front and high idle generally go hand in hand. I still have the option of putting my e-brake down and engaging high idle through my cruise control. That's a long winded answer, but it might be your issue if you're using your winter front.
 

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Are you running a winter front on your truck? I never used to run mine on my LML. Never needed it. Once I deleted and installed my tunes, my truck started running way cooler. So I put my winter front on. Now it barely ever goes into high idle unless it's really cold. Reason being...... the winter front holds the warm air from the engine in. So all of the air temp sensors are getting incorrect readings. When I pull up and park at -15, the warm air under the hood makes the truck think it's a lot warmer than it is. So when I start the truck the next time everything is wickity wack. It would be nice if there was some sort of fix for it seeing as the winter front and high idle generally go hand in hand. I still have the option of putting my e-brake down and engaging high idle through my cruise control. That's a long winded answer, but it might be your issue if you're using your winter front.

I'm not running a winter front on mine. I wish I had one though because my truck never gets up to temp in the winter. But I know that if you are running one you can move the sensor that is located behind the bumper so you get a more accurate reading.
 

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I'm not running a winter front on mine. I wish I had one though because my truck never gets up to temp in the winter. But I know that if you are running one you can move the sensor that is located behind the bumper so you get a more accurate reading.
That is good to know. Do you know where guys are moving them too? I'll run a search as I don't want to hijack this thread too much. Moving that sensor would likely only correct the temperature reading on my dash though would it not? I'm not 100% sure but I would think that it is the IAT sensor that decides whether or not the truck goes into high idle.
 

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That is good to know. Do you know where guys are moving them too? I'll run a search as I don't want to hijack this thread too much. Moving that sensor would likely only correct the temperature reading on my dash though would it not? I'm not 100% sure but I would think that it is the IAT sensor that decides whether or not the truck goes into high idle.

I've heard guys say they run them out from behind the bumper where the tow hook comes out. I'm not sure if it lets the truck know to high idle or not but i don't know of any other ambient temp sensors so I'd say it's a good chance.
 

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I flashed my truck back in the summer so I'm not 100% sure EFI live is the cause of it. But sometimes when it's really cold I can let my truck idle for 15 mins and high idle won't kick on. Then if I drive 5 miles and stop put the truck in park it'll kick on instantly.
It is a little harder to tell then. Have you tried flashing your Stock File? If it is erratic, I would guess a sensor is having issues. However, it may just be that the truck is trying to get to a safe temp before it activates high idle.
 

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It is a little harder to tell then. Have you tried flashing your Stock File? If it is erratic, I would guess a sensor is having issues. However, it may just be that the truck is trying to get to a safe temp before it activates high idle.

It is probably just trying to get to a safe temp then. It seems like it only does it when it's really cold out. When it's just below 32 degrees it usually kicks right in. I haven't tried flashing my stock file yet. And my ambient temp sensor seems to be pretty accurate with my outside thermometer so I don't think that is the issue.
 

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If you are still having the problem with your elevated idle I had issues with mine where it would work sometimes and sometimes it would not. I have EFI live tunes from motor ops also. Mine turned out to be my brake switch attached to the brake pedal arm. I got one from the dealership for about 25 bucks and it only took 20 minutes to change out. Mine works everytime it is suppose to now.
 
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