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Been using 89 octane for awhile and no surging on morning startups. Engine running smoothly and am actually getting slightly better gas mileage. Reading about differences between octane levels. I had been filling up with 93 octane which is used for high compression ratio engines like my wife’s Mercedes gle 400 v6 turbo. The higher octane resists auto ignition. That engine is about 13:1 where the hemi is around 10:1. I think the higher compression engines create more pressure in the cylinder which, in turn, causes a much higher cylinder temp. That’s why it needs a fuel that resists premature combustion. The hemi doesn’t create as much pressure in cylinder head, therefore a lower temp that doesn’t ignite the high octane fuel completely. So in the morning when the engine is cold the engine surges from an incomplete fuel combustion until the engine warms up. Maybe. All I can say is that the surges have stopped.
Been using 89 octane for awhile and no surging on morning startups. Engine running smoothly and am actually getting slightly better gas mileage. Reading about differences between octane levels. I had been filling up with 93 octane which is used for high compression ratio engines like my wife’s Mercedes gle 400 v6 turbo. The higher octane resists auto ignition. That engine is about 13:1 where the hemi is around 10:1. I think the higher compression engines create more pressure in the cylinder which, in turn, causes a much higher cylinder temp. That’s why it needs a fuel that resists premature combustion. The hemi doesn’t create as much pressure in cylinder head, therefore a lower temp that doesn’t ignite the high octane fuel completely. So in the morning when the engine is cold the engine surges from an incomplete fuel combustion until the engine warms up. Maybe. All I can say is that the surges have stopped.
Increasing the octane rating of gasoline, increases the temperature required to suppress pre-ignition of the fuel. Octane by itself will not be the determining factor that causes combustion temperatures to rise.
Heat generated in the combustion chamber of a reciprocating engine is the result of thermodynamic properties of the fuel, and the elements found in the air. Generally, the amount of heat generated is determined by the BTU output of the burn, which is a measure of the fuel’s energy. Fuels are made up of various combinations of oxygen, hydrogen, carbon, nitrogen, as well as deactivators, corrosion inhibitors, oxygenates and antioxidants. Each supplier will have a different recipe for any given fuel. To increase octane ratings there are a wide variety of compounds used, such as ethanol, toluene, benzene, methyl-tertiary-butyl-ether (MTBE), just to name a few, but generally have no effect on energy of the fuel.
Increasing the octane rating of gasoline, increases the temperature required to suppress pre-ignition of the fuel. Octane by itself will not be the determining factor that causes combustion temperatures to rise.
Heat generated in the combustion chamber of a reciprocating engine is the result of thermodynamic properties of the fuel, and the elements found in the air. Generally, the amount of heat generated is determined by the BTU output of the burn, which is a measure of the fuel’s energy. Fuels are made up of various combinations of oxygen, hydrogen, carbon, nitrogen, as well as deactivators, corrosion inhibitors, oxygenates and antioxidants. Each supplier will have a different recipe for any given fuel. To increase octane ratings there are a wide variety of compounds used, such as ethanol, toluene, benzene, methyl-tertiary-butyl-ether (MTBE), just to name a few, but generally have no effect on energy of the fuel.
In the morning if I press the brake-start button right away, I get a rough start, sometimes stalling out. It will start normally by pressing the start button twice into the run position, then pressing the brake and start button. Seemed like a leaky injector(s) at first but now think some modules need time to wake up
Had the truck 9 months, now pushing 18,000 miles, we live at 6000 feet, and park on an incline of about 15 degrees. Rough start every time since new, dealer said not to worry. I didn't.
Until a recent service visit, now much worse after service at 15,000 miles where MAF/throttle body was cleaned. Now it has stalled and bucked a few times when placed in gear. I Will be taking it back in. Don't even get me going why a throttle body has to be cleaned every 15,000 miles, thats like 60's tune up distances... It seems worse on warmer mornings, when it was 25 degrees it didn't seem to have issues.
I have tried nothing but 87, nothing but 93, I tried nothing but Shell fuel. Mixtures of all. I tried adding fuel additive to remove any sign of water. No change. I use Circle K or Speedway because thats all we have around here.
I lived in Scottsdale and it didn't seem to do this rough start sitting flat on a driveway. Only happens first start then hauls like a beast.
Update, after writing above I went to town and on start it backfired through intake and had about 4 seconds of wild rpm fluctuations and I smelled lots of gas, then all fine. I went straight to dealer with video of what just happened and they now have it
Sounds like the classic symptom of leaky injectors. It's definitely not normal, just because another POS does it is not an indication nothing is wrong. I'm sure the people burning up in a Pinto found little comfort that others caught fire as well
Sounds like the classic symptom of leaky injectors. It's definitely not normal, just because another POS does it is not an indication nothing is wrong. I'm sure the people burning up in a Pinto found little comfort that others caught fire as well
Back from dealer. Odd, they wanted to know if I wanted them to keep it longer? At first they could duplicate it, then second day it started fine. Employee states now that I mention it his does this and never thought about it. I think things going bang in the intake is probably wrong.
It throws no codes nor has any memory of it doing what it does. Reminds me of college.
I'm tryin shell gas for a few weeks. Maybe some additives.
In my experience working on 2000 era BMW's and 80's efi mustangs, any knock, bang, stall, backfire threw a code. Why doesn't a 2020 record that?
There is another version which looks like that but is more like seafoam. I did not use that.
About $9 a small bottle, don't buy the quart size. Sort of an STP but synthetic and does not hurt mileage. Just stops the lifter tick on start, and apparently in my case, a collapsed lifter or two, which is my first guess diagnoses of the issue.
I also used this stuff on my 2015 jeep 3.6 which is horribly noisy on the top end until oil flows, about 5 seconds, this stuff made it a silent start.
Thats all I have for now, I'll add more later if anything changes, but again, I think the fix was the lucas oil additive, the injector stuff was just insurance.
Also, I don't think altitude or incline has much to do with the rough start if any. Dealer rep said his did it level in a warm garage at same altitude and down in valley at 1,000 ft elevation.
I find it interesting the thing that probably fixed this, lucas low vis oil stabilizer, is name for exactly the reason most big engines have noise issue on starts, low viscosity oil runs off everything overnight.
One week on from lucas oil modifier, no knocks or stutters, just a normal efi grumble on start. I call this fix plausible.
Also, I don't think altitude or incline has much to do with the rough start if any. Dealer rep said his did it level in a warm garage at same altitude and down in valley at 1,000 ft elevation.
I find it interesting the thing that probably fixed this, lucas low vis oil stabilizer, is name for exactly the reason most big engines have noise issue on starts, low viscosity oil runs off everything overnight.
One week on from lucas oil modifier, no knocks or stutters, just a normal efi grumble on start. I call this fix plausible.
Also, I don't think altitude or incline has much to do with the rough start if any. Dealer rep said his did it level in a warm garage at same altitude and down in valley at 1,000 ft elevation.
I find it interesting the thing that probably fixed this, lucas low vis oil stabilizer, is name for exactly the reason most big engines have noise issue on starts, low viscosity oil runs off everything overnight.
One week on from lucas oil modifier, no knocks or stutters, just a normal efi grumble on start. I call this fix plausible.
I think i may have to give the lucas oil a try. Mine has sputtered 4 times in the past 2 weeks. Just hit 18k on it. Never an issue before. Today, it actually stalled all the way out. Gave it a few seconds and it started on the second try. Really frustrating for such an expensive truck.
Mine has stopped doing it. Lasted through three tanks of fuel. Not sure what exactly the issue was, but also had an issue where my battery mysteriously died overnight and wouldn't take a change from battery charger. Jumped it and took it to dealer and battery tested fine, and hasn't had any issues since.
...and today it started just fine. Really drives me nuts. I ordered a 20oz bottle of Techron that I'll plan to dump in there at next fill up. I'm really hoping its just bad gas. This will be the 3rd fill up since the problem first started a few weeks back.
I'm in Maryland so I don't believe it would be elevation related.
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