Nearly Died Last Night!

SierraAT · June 19, 2015

I have the 5.3 and been using E85 quite a bit recently, definitely a noticeable increase in HP from it, quite drastic feeling actually. I'd say if you have the option for E85 in your area fill up with it, the savings in price vs 89 octane pretty much makes up for the decrease in MPG.

Rawyzf · June 19, 2015

I wish I could run e85.

Alter Ego Trip · June 20, 2015

I have the 5.3 and been using E85 quite a bit recently, definitely a noticeable increase in HP from it, quite drastic feeling actually. I'd say if you have the option for E85 in your area fill up with it, the savings in price vs 89 octane pretty much makes up for the decrease in MPG.

I hate to burst your bubble but the hp increase you are feeling is psychosomatic. E85 is big in the tuning world as you can run some significant timing advance without detonation due to E85's slow burning properties. A stock Silverado will see no increase in HP without advancing the timing. The draw to E85 is the cheap price you can buy it for at the pump compared to 89+. You have to do the math however to see if the lower fuel economy offsets the price savings.

Imcrazy · June 20, 2015

Manual mode in these trucks isn't shifting the gears like you would with a manual though, it's just like any other auto that has a 1,2,3 on the dash where it just won't shift past the gear you choose. I haven't found a real need for manual mode, maybe if I get stuck in snow or mud, but that's about it. I haven't had any issues with the trans in my '14 in any situation.

I like it for driving in the mountains and using the trans to hold speed. Also it's better to kick it down a couple gears ahead of time on the highway in a tight situation IMO.

Spurshot · June 20, 2015

I've had the experience that the OP had. It's happened numerous times. I think I've figured out the conditions that have to be in play to cause it. The truck has to be going fast enough that it will shift to a higher gear, possibly 5th or 6th in my truck. But it has to be going slow enough that it needs to be in 1st or 2nd gear to accelerate at the desired rate. Usually 1st is where I see it. My recollection is that it's the same scenario as the OP. Crawling along at about 20-25 mph, then I see an opening in the traffic lane to the left of me, I nail it, turn into the lane, .............................................................. and wait. It always eventually gets going. But the delay can be incredibly long. Now that I know the way the truck works in these situations, I go to manual. It's a 'work around' procedure, until I can get a tune and possibly cure the issue.

Just keep in mind that even the old Turbo-Hydromatic 3 speeds that had electric or mechanical "kickdown" systems, took some time to shift down. But this is ridiculous.

j-ten-ner · June 20, 2015

I know my truck isn't a K2.

When I stomp on the pedal fast but only 1/2 or 3/4 of the way it takes a lot of thinking for the truck to figure what I'm up to.

But when I floor it, and I mean literally down to the floor , then he takes off like a raped ape.

Do you guys push the pedal to the floor or just close?

so long

j-ten-ner

CounterMeasure · June 21, 2015

My 6.2 has a notch in the pedal about 3/4ths the travel that is meant to let the drive know that pressing anymore will cause a downshift. There's even a TSB on it because apparently people thought the notch was a defect. While the notch is not a defect, the design that the transmission will downshift at that point is. There had been cases where it didn't downshift at all. Other times, I've floored it, and waited literally seconds for the transmission to decide now many gears to drop, then actually start downshifting, then apply the throttle. While it has the horses available, sometimes it drives like a fat pig.

jayjay361 · June 22, 2015

My 2014 All Terrain did the same the other day, I was driving , accelerating at 40+ mph, & the truck just went into limp mode, as if it were running out of gas, I pushed down on the accelerator, & it did nothing, then bam, it hit 4k rpm & STILL didn't accelerate.. Then it upshifted & finally woke up & went... It's been towed to the dealer, some computer issues, apparently

NitroCherokee · June 22, 2015

I hate to burst your bubble but the hp increase you are feeling is psychosomatic. E85 is big in the tuning world as you can run some significant timing advance without detonation due to E85's slow burning properties. A stock Silverado will see no increase in HP without advancing the timing. The draw to E85 is the cheap price you can buy it for at the pump compared to 89+. You have to do the math however to see if the lower fuel economy offsets the price savings.

You didn't burst his bubble at all, you are wrong. You will indeed get a horsepower bump running E85 on a stock tuned truck. You are correct about the timing advance which a stock tune also will advance the timing

Alter Ego Trip · June 22, 2015

You didn't burst his bubble at all, you are wrong. You will indeed get a horsepower bump running E85 on a stock tuned truck. You are correct about the timing advance which a stock tune also will advance the timing

Umm, no I'm not.

Factory trucks are designed to run on 89 octane fuel. The timing is optimized for this octane amount. Running higher octane won't increase hp at all. Now if the factory tune is optimized for a higher octane then what you are currently running, then obviously you will see a slight hp bump (heavy on the slight).

I ran a supercharged Mustang that was initially tuned for both 91 and race fuel. Running race fuel on my 91 map resulted in absolutely no extra hp then when I was running 91.

Show me a before and after dyno with 89/91 and E85 where the E85 provides more hp on a factory tune.

NitroCherokee · June 22, 2015

Umm, no I'm not.

Factory trucks are designed to run on 89 octane fuel. The timing is optimized for this octane amount. Running higher octane won't increase hp at all. Now if the factory tune is optimized for a higher octane then what you are currently running, then obviously you will see a slight hp bump (heavy on the slight).

I ran a supercharged Mustang that was initially tuned for both 91 and race fuel. Running race fuel on my 91 map resulted in absolutely no extra hp then when I was running 91.

Show me a before and after dyno with 89/91 and E85 where the E85 provides more hp on a factory tune.

Here is one thread on it

http://www.gm-trucks.com/forums/topic/153351-soused-e85-yet/

I am not going to argue with you tho, I mean you did own a Mustang with a race fuel tune so obviously I have no idea

raym0016 · June 22, 2015

So, which is it? I have seen many people say that you get a jump in power at the price of economy. I have also read that e85 helps with the acceleration and runs cleaner that 87 (or 89 for that matter). I was planning on getting a truck at the end of the year and one of the options I am mandating is the E85 capability because of what I mentioned above+E85 in MN is ~$1.89/gallon vs. $2.69 for 87. So unless there is a more than 30% drop in economy it would actually be cheaper to run E85, and better for the truck vs. running 87. It would make even more sense $$ wise if were to use 89 octane. I also understood that there is a sensor in the tank that senses the blend/octane level and adjusts accordingly. Have I been misled? or is Alter Ego Trip mistaken?

You didn't burst his bubble at all, you are wrong. You will indeed get a horsepower bump running E85 on a stock tuned truck. You are correct about the timing advance which a stock tune also will advance the timing

Umm, no I'm not.

Factory trucks are designed to run on 89 octane fuel. The timing is optimized for this octane amount. Running higher octane won't increase hp at all. Now if the factory tune is optimized for a higher octane then what you are currently running, then obviously you will see a slight hp bump (heavy on the slight).

I ran a supercharged Mustang that was initially tuned for both 91 and race fuel. Running race fuel on my 91 map resulted in absolutely no extra hp then when I was running 91.

Show me a before and after dyno with 89/91 and E85 where the E85 provides more hp on a factory tune.

Edit: It looks like Nitro Cherokee is right according to this thread: http://www.lingenfelter.com/LPEforumfiles/showthread.php?2248-2014-1500-Silverado-with-5-3L-L83-engine-work-begins.

The question I have though is would that make a difference in an issue like the OP is describing?

Alter Ego Trip · June 22, 2015

Here is one thread on it

http://www.gm-trucks.com/forums/topic/153351-soused-e85-yet/

I am not going to argue with you tho, I mean you did own a Mustang with a race fuel tune so obviously I have no idea

Well here is one statement that stands out to me in that link.

"The engine appears to run a little more spark (1.5 degrees peak, 1.7 degrees average) and run a little leaner (0.6 average and 0.5 peak in terms of lambda, not AFR of course). With the added fuel volume and the DI they may also be getting adding charge cooling benefits."

So in the test the motor was running more timing advance on the E85 vs the 91, which backs my statement that there will be no hp increase without increasing timing or adjusting AF ratios.

I will stand corrected that the Silverados won't benefit from E85. I'd like to see some more definitive tests to confirm this however. Butt dyno tests hold no water to me. There are a million factors that would appear to make a truck run quicker from one day to the next.

The question I'd like to have answered is if trucks that are E85 compatible are tuned around the E85 from the factory and the computer is retarding the timing on lower quality fuels. It would appear that this would be the case based on Lingenfelters findings.

ember1205 · June 22, 2015

Well here is one statement that stands out to me in that link.

"The engine appears to run a little more spark (1.5 degrees peak, 1.7 degrees average) and run a little leaner (0.6 average and 0.5 peak in terms of lambda, not AFR of course). With the added fuel volume and the DI they may also be getting adding charge cooling benefits."

So in the test the motor was running more timing advance on the E85 vs the 91, which backs my statement that there will be no hp increase without increasing timing or adjusting AF ratios.

I will stand corrected that the Silverados won't benefit from E85. I'd like to see some more definitive tests to confirm this however. Butt dyno tests hold no water to me. There are a million factors that would appear to make a truck run quicker from one day to the next.

The question I'd like to have answered is if trucks that are E85 compatible are tuned around the E85 from the factory and the computer is retarding the timing on lower quality fuels. It would appear that this would be the case based on Lingenfelters findings.

There is a sensor to detect the ethanol ratio and it adjusts motor configuration / tuning accordingly. So, while you are correct in that lack of advanced timing on E85 won't produce a HP gain, you are wrong in the assumption that the motor is "tuned" just one way. It adapts to the fuel that it senses.

SouthernSilveradoGuy85 · June 22, 2015

Umm, no I'm not.

Factory trucks are designed to run on 89 octane fuel. The timing is optimized for this octane amount. Running higher octane won't increase hp at all. Now if the factory tune is optimized for a higher octane then what you are currently running, then obviously you will see a slight hp bump (heavy on the slight).

I ran a supercharged Mustang that was initially tuned for both 91 and race fuel. Running race fuel on my 91 map resulted in absolutely no extra hp then when I was running 91.

Show me a before and after dyno with 89/91 and E85 where the E85 provides more hp on a factory tune.

E85 needs more spark and these trucks have a sensor to tell the system that it's E85 and adjust for it so you do get a slight gain. From what I understand it needs more spark since it needs more fuel to burn and well more spark and fuel means a gain which also means lower MPGS. That's why you feel the performance gain but looks MPG since with E85 it takes more fuel to burn. Of course you're right about if it doesn't come from the factory tuned to run on E85 then you won't feek anything. It either needs that sensor or put a tune in for E85 but running the tune I'm thinking you'll have to always put E85 in. You're confusing Octane rating and Ethanol. Normal gas has about 15% ethanol while E85 means Ethanol and 85%. As for octane, and engine won't run as well if you put a lower octane than it's tuned for while putting a higher octane won't really do anything other than just burn cleaner. I've ran 87 octane in every truck I've owned and never had a problem. The trucks with the 4.3 V6 or 5.3 V8 come tuned for 87 while 6.2 is tuned for 91 I believe.