7.3 Detonation at start up

[Big John Son]

I've been running 87 octane and heard a hint of detonation when firing up my truck the other day. I started it a few times after it was already warmed up and heard it each time. I guess it could be shitty gas, but I think from now on I'm going to run 89 octane.

 

[Iron Man]

I've been running 87 octane and heard a hint of detonation when firing up my truck the other day. I started it a few times after it was already warmed up and heard it each time. I guess it could be shitty gas, but I think from now on I'm going to run 89 octane.

It still says on your profile Current Ride F150 XLT. Whats up with that BIG JOHN. Is your Tremor not your first choice for Cruisin
LOL. Love ya BIG JOHN. ? ? ? ?

 

[Accuracy International]

My 6.2L Raptor did that when I first got it. Been running Premium for the last 10 years.

 

[richtor]

87 and cold weather?

 

[PapaRaptor]

I've been running 87 octane and heard a hint of detonation when firing up my truck the other day. I started it a few times after it was already warmed up and heard it each time. I guess it could be shitty gas, but I think from now on I'm going to run 89 octane.

They offer 87, mid grade 89 or premium 93 octane. Be careful where you purchase the 89 octane from. Its not sold as much as premium or 87 so it sits in the tank at the station for longer times. My daughter ran a few tanks of 89 from a local station and after a few tanks the car would not stay running. The car was towed to the dealership where they had the gasoline sent to a lab and found it to be bad from sitting too long. We took the receipts back to the owner of the station ( $3200.00 plus) for all the work done and the lab test, draining the old fuel out, new injectors....... They claim the fuel is warranted, but we found out else wise. They did nothing. So we never purchase anything from them and she now runs the premium fuel.
I always run only 93 in my gen 1 Raptor never any issues

 

[Big John Son]

87 and cold weather?

Never had a problem with 87 on any of my numerous F-150's.

 

[Big John Son]

It still says on your profile Current Ride F150 XLT. Whats up with that BIG JOHN. Is your Tremor not your first choice for Cruisin
LOL. Love ya BIG JOHN. ? ? ? ?

Yo, good call. I have to change that to my Prius !

 

[Big John Son]

They offer 87, mid grade 89 or premium 93 octane. Be careful where you purchase the 89 octane from. Its not sold as much as premium or 87 so it sits in the tank at the station for longer times. My daughter ran a few tanks of 89 from a local station and after a few tanks the car would not stay running. The car was towed to the dealership where they had the gasoline sent to a lab and found it to be bad from sitting too long. We took the receipts back to the owner of the station ( $3200.00 plus) for all the work done and the lab test, draining the old fuel out, new injectors....... They claim the fuel is warranted, but we found out else wise. They did nothing. So we never purchase anything from them and she now runs the premium fuel.
I always run only 93 in my gen 1 Raptor never any issues

Good lookin out. I'll just run premium then.

 

[davidb1841]

Here in NC alot of the newer stations have NON-Ethynol gasoline (no alcohol) and I am sure that is also better....except again....probably true what Papa says about this gas to...it probably sits around alot.

 

[richtor]

Yo, good call. I have to change that to my Prius !

How do I change it?

Hit your name up top then go to account details and scroll down.

 

[Big John Son]

Hit your name up top then go to account details and scroll down.

Yeah, just found it, thanks. I fixed it for the Iron Man! ?

 

[Colfaxent]

I would have the truck checked out at your dealer. It shouldnt detonate on start up . The engine is designed to run on 87 from what you say so i would recommend trying a different gas station first and see if it still detonates. There can be a difference in Octane and quality of fuel between brands. It really isnt a good idea to run Higher Octane in an engine that does not require it, higher octane is a slower burning fuel and will also cause more carbon build up which in the long run will cause issues besides being a waste of your money. It seems very odd that it would detonate on start up, does it also do it under a load? Most often engines with poor octane fuel detonate under a load like when you tip in to the throttle on a steep grade. Another question is does it go away as it is warmed up? If so it sounds more like piston slap. and goes away as he piston expands when it warms up. Has it just started since it started getting colder? Being that we cant hear it I definitely would bring it in to the dealer. Good luck, let us know what you find out.

 

[Big John Son]

I would have the truck checked out at your dealer. It shouldnt detonate on start up . The engine is designed to run on 87 from what you say so i would recommend trying a different gas station first and see if it still detonates. There can be a difference in Octane and quality of fuel between brands. It really isnt a good idea to run Higher Octane in an engine that does not require it, higher octane is a slower burning fuel and will also cause more carbon build up which in the long run will cause issues besides being a waste of your money. It seems very odd that it would detonate on start up, does it also do it under a load? Most often engines with poor octane fuel detonate under a load like when you tip in to the throttle on a steep grade. Another question is does it go away as it is warmed up? If so it sounds more like piston slap. and goes away as he piston expands when it warms up. Has it just started since it started getting colder? Being that we cant hear it I definitely would bring it in to the dealer. Good luck, let us know what you find out.

The truck had been warmed up already and I shut it down for a second, started it back up to close my window and heard it. Proceeded to shut down and start it back up a couple times and heard it each time. Once running it went away. I hooked my boat up and towed it without hearing it as well. I am still using the same tank of fuel and just went out to driveway to start it cold and no detonation sound. Really odd. Maybe it was where I was parked and it just resonated off the glass store fronts? I dunno, I am pretty familiar with the sound of detonation since I grew up in the 70's when Dads woody station wagon would stay running after the key was turned off for 10 minutes lol .

 

[Dc501]

Most newer stations use a system to blend 87 and 92 to get 89. 89 is a waste of money. Unless your vehicle is a higher compression engine 92 won’t make any difference, I think it’s 10-1 compression where its better to use 92. If your having an issue you need to have a dealer look at it. Either bad batch of gas or something is wrong. There are a zillion of them running 87 just fine.

 

[PapaRaptor]

Good lookin out. I'll just run premium then.

You could just rotate between 87 and premium. Top off with the opposite one every half tank.

Did you possibly get fuel when the tanker was filling up at the station? There is talk about the fuel getting churned up when they fill the tanks. Some of the old guys I know, will not fill up if there is a tanker at the station. Not sure it there is any truth to that, but makes sense if you had poor fuel quality.

 

[7.3Tremor]

I run 93 in mine, not sure if it helps or not but I run it pretty hard.

 

[7.3Tremor]

Most newer stations use a system to blend 87 and 92 to get 89. 89 is a waste of money. Unless your vehicle is a higher compression engine 92 won’t make any difference, I think it’s 10-1 compression where its better to use 92. If your having an issue you need to have a dealer look at it. Either bad batch of gas or something is wrong. There are a zillion of them running 87 just fine.

I believe the compression ratio on the 7.3 is this

“On regular-octane fuel, the 7.3L runs a 10.5:1 compression ratio with a conventional port fuel injection system.“

 

[Big John Son]

You could just rotate between 87 and premium. Top off with the opposite one every half tank.

Did you possibly get fuel when the tanker was filling up at the station? There is talk about the fuel getting churned up when they fill the tanks. Some of the old guys I know, will not fill up if there is a tanker at the station. Not sure it there is any truth to that, but makes sense if you had poor fuel quality.

No tanker present at last fill up. I am chalking this up to bad gas though, since it has 4000 miles and it's always run fine on 87. I'll monitor, and if I hear it again bring it to the dealer.

 

[Big John Son]

I must say, I always appreciate all the advice here. This time, I'm a little sorry I asked. You guys be like...

Don't run 89
Run 93
No Don't run 93
Mix it
87 is fine
I run 93
87 in the cold?

It's like I just asked my wife and daughters what they want for dinner!

 

[Trämör]

I must say, I always appreciate all the advice here. This time, I'm a little sorry I asked. You guys be like...

Don't run 89
Run 93
No Don't run 93
Mix it
87 is fine
I run 93
87 in the cold?

It's like I just asked my wife and daughters what they want for dinner!

I’ve recently done a bit of research because I always used to put expensive Shell Nitro V Power 93 in my trucks & cars. Here’s the bottom line, for the cases where your engine does NOT require higher octane due to compression ratios (such as most engines, except high performance ones):
- 87 octane in most cases actually yields BETTER power delivery than 93 octane. The reason being that people confuse octane with some kind of energy value of fuel, whereas it is really just the ability of the fuel to withstand pinging (speak premature detonation due to compression). Therefore, lower octane ignites “easier” at lower compression under normal conditions. Note that this relationship changes under heavy loads, actually causing 93 octane to yield a better performance under loads such as towing.
- This leaves you with the argument that 93 octane fuels or the VPowers of this world ensure better engine longevity due to the increased volume of detergents in the fuel. While this is certainly true and proven, it has very little to do with the octane level. It is purely a detergent question, which, as per common research, suggests that 87 octane fuel from top tier providers has “just enough detergents” to keep your engine clean and you don’t need the added ones from Shell VPower et cetera.
- The last argument for using higher octane fuel is mpg and this is highly dependent on the engine and can be quite different from type to type. However, Ford V8 engines haven proven to run more efficient on higher octanes than other manufacturers V8s. This difference is however negligible as we are speaking a maximum better result of 0.3-0.6 mpg more. Making the math with top tier fuels of 87 octane and 93 octane, this makes no sense from an economic perspective.

So, clearly, 93 octane and the VPowers of this world are a major consumer ripoff. Continue putting good gas in your truck, from a well known brand, but don’t bother with 93. 87 is just fine.

lastly, now come the fancy folks with the blanket statement of “You pay 80k on a truck, why bother saving 8$ on a full tank of gas, sacrificing longevity. As stated above, the longevity argument is invalid, and so are the performance ones outside of high load applications. So technically, this isn’t about money for me. I just don’t like being fooled by the system and buy into unsubstantiated beliefs. I feel better running 87 knowing it’s the intelligent choice versus running 93 for the sole benefit of the Oil & Gas shareholders.