Switched Fuel from Shell to Costco and Noticed Something Strange

[JC SSP]

Hmmm I wasn’t thinking of octane booster. But throw one of those in there too lol

 

[WJBertrand]

Ok I am going to switch to Premium at Costco. Their premium is the same price as the Shell Regular. Plus there whole setup is new so their tanks should be free from most gunk.
I remember when I bought it the son of the owner said he thought that his parents ran premium in it. Is there any way to verify if the stock tune has been modified?
Also I have always believed if you run premium in an engine that is designed to run on regular that the engine would develop more carbon build up do to an incomplete burn.

I don’t know about the older V8s and V6s, but the Coyote 5.0 can burn either regular or premium as delivered by the factory. The knock sensor system backs off the timing if any detonation is detected. As the system keeps the timing retarded compared to when running premium, you lose some performance and I think MPGs as well.
My car has a FRPP ProCal tune that came with instructions to never use regular. I was using premium before the tune anyway as I enjoyed the snappier performance.

 

[07 Boss]

The octane of the gas has nothing to do with the way it burns so it will not improve performance or make your car feel snappier. What it allows is more compression and more timing. These things will improve performance. If you switch from regular to premium there won't be any difference in performance unless you add more timing unless you have a detonation issue with the lower octane. With that said, I'm not sure how much boost is used in the Stage 1 but I'm going to assume its about 5-6 psi. You may be able to run regular without any issues but I would always run premium for any boosted application.

My wife's car has got a turbo and it says you can run regular but I always use premium in it.

Try and stay away from octane boosters. They can be beneficial but can also lead to other problems depending on the brand and additives.

 

[MrBhp]

Stage one is n/a.
I get what you're saying Boss, but the ecm is probably pulling timing with 87 octane. Which means premium will prevent timing retard. Yes/no/maybe?

 

[Miker]

Stage one is n/a.
I get what you're saying Boss, but the ecm is probably pulling timing with 87 octane. Which means premium will prevent timing retard. Yes/no/maybe?

And here is something I don't understand. The 2005 4.6 has knock sensors. But I have read that only the 2008 Bullitt can benefit from running premium because their system will up the timing with premium. Like wise the 2010 4.6 and the Bullitt that have 315hp will retard the timing if regular is used.
I understand octane and what it does. I am thinking more and more that I just got a bad tank of gas. Everything I have read says that the 300hp 4.6 runs fine on regular and anything else is a waste of money. I have also searched high and wide and everything I have read says the 2005 Stage 1 Roush motor is a stock GT 4.6 with the only modification being the Roush mufflers.

 

[JimC]

Until the 2008 Bullitt the knock sensors didn't cause the computer to do anything. No other Mustang until 2011 think used the sensors to adjust for octane.

So if you have a 2005 to 2010, running premium without a tune does nothing but lighten your wallet.


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[MrBhp]

The cure for all this is, of course, a premium fuel tune! That way you have to run premium.

 

[dark steed]

I will say that years ago (before a CAI/tune), I got better fuel mileage on premium in my 2007 C/S. And that was hand calculated over several tanks of each. The “butt dyno” felt like it had improved performance, but the calculator proved that the mileage increase more than offset the additional cost.


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[WJBertrand]

Until the 2008 Bullitt the knock sensors didn't cause the computer to do anything. No other Mustang until 2011 think used the sensors to adjust for octane.

So if you have a 2005 to 2010, running premium without a tune does nothing but lighten your wallet.


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Why would Ford bother fitting knock sensors if they weren’t using them somehow?


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[Miker]

Why would Ford bother fitting knock sensors if they weren’t using them somehow?


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I think what he meant is that until the Bullitt timing was not advanced when higher octane was sensed. But it is confusing. Of course the knock sensors will pull timing from the 2005 4.6.
It seems like a tuner that added timing to the 2005 to run on premium would act just like the tune that Ford added to the Bullitt and the 2010 GT. But maybe they don't have that capability? I am not against getting a tuner but some of the negative responses on sites like AM and LMR give me pause.

 

[dark steed]

I’ve had mine since 2008, and this is the first I’ve ever heard that it will not advance timing. I do know for an empirical fact that I got better fuel mileage on premium fuel. It was not a computer calculated mileage, it was physical hand calculated mileage over several tanks of both types of fuel. That alone would make me believe it was able to advance timing based on fuel.
Previous to that I had a 1998 XLT Explorer 4x4 (SOHC V6), and it got better fuel mileage on regular. That’s certainly not apples to apples, but I do realize some will run better on regular fuel.


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[Miker]

I’ve had mine since 2008, and this is the first I’ve ever heard that it will not advance timing. I do know for an empirical fact that I got better fuel mileage on premium fuel. It was not a computer calculated mileage, it was physical hand calculated mileage over several tanks of both types of fuel. That alone would make me believe it was able to advance timing based on fuel.
Previous to that I had a 1998 XLT Explorer 4x4 (SOHC V6), and it got better fuel mileage on regular. That’s certainly not apples to apples, but I do realize some will run better on regular fuel.



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What year is yours? I have also noticed that a motorcycle I owned that was designed to run on regular got better fuel mileage on premium. I live in NorCal and I am at least going to try a tank of premium as I believe the car will run a little cooler with the delayed burn. It's hot as hades here! Hopefully I will notice a seat of the pants improvement as well.

 

[dark steed]

Mine is a 2007, it has had the Mishimoto radiator in it for several years now, but never ran hot on the OEM setup.
It did run hot on my daughter the other day on a 93F day in heavy stop and go traffic. She was coming to a family birthday party and had to run the heat wide open the rest of the drive.
6 months pregnant + 93F + heater on = one cranky girl! Lol
I put new radiator hoses on it, but did not change the thermostat because it was hot and I would’ve had to take the intake off. The upper radiator hose seemed to be collapsing, a little, but it’s on the pressure side and not the suction side. I don’t think it was the problem…

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[07 Boss]

Stage one is n/a.
I get what you're saying Boss, but the ecm is probably pulling timing with 87 octane. Which means premium will prevent timing retard. Yes/no/maybe?

If it's na it probably is tuned for 87. You would be able to determine if timing is being pulled through data logging. But yes, IF timing is being pulled because of detonation then switching to a higher octane will help performance.

 

[Midlife Crises]

And here is something I don't understand. The 2005 4.6 has knock sensors. But I have read that only the 2008 Bullitt can benefit from running premium because their system will up the timing with premium. Like wise the 2010 4.6 and the Bullitt that have 315hp will retard the timing if regular is used.
I understand octane and what it does. I am thinking more and more that I just got a bad tank of gas. Everything I have read says that the 300hp 4.6 runs fine on regular and anything else is a waste of money. I have also searched high and wide and everything I have read says the 2005 Stage 1 Roush motor is a stock GT 4.6 with the only modification being the Roush mufflers.

The 2010 GT has a different intake manifold and cold air inlet than previous 4.6 GTs. That allowed Ford to tune a little more power into the Mustang. 315 HP and 335 Lb torque. You can datalog the engine and see the knock sensors at work and the computer most certainly pulls ignition timing when knock is detected. Octane level has a direct effect on this. Yes, higher octane fuel allows you to make more power if you can capitalize on it.

 

[yote0]

The 2010 GT has a different intake manifold and cold air inlet than previous 4.6 GTs. That allowed Ford to tune a little more power into the Mustang. 315 HP and 335 Lb torque.

Well, 325 ft/lbs. Redline was raised to 6500 RPM as well.

 

[Ret]

When I bought my 2012 GT 5.0 I asked if it the car ran on premium or regular, the dealer had no idea. At the time I was driving a 2008 Mustang GT/CS with 300 HP. I ran regular in it without problem. The 2012 had an additional 112 HP over the 08 so I was assuming it would need premium. I did some research and found an article that stated the coyote engine had a computer that could distinguish if the car was running on regular or premium and adjust; accordingly, if it hadn't had an after-market adjustment.

I run regular, runs great and I buy the gasoline from a variety of stations including Costco. No problems. Will the regular overtime do damage to the engine, I'll have to leave that question to you guys; I only know to drive them.

I live in North Idaho and we have a had a few days of just shy of 100 degrees, so nothing compared to the earlier post.

 

[GlassTop09]

Man, this discussion got out there pretty fast....................

Read here: 2005 Ford Mustang Research Center (mustangspecs.com)

Click on the Modern Years dropdown menu then under 5th Gen click on any MY from 05 thru 10 to read up..... you'll see which MY & model S197 4.6L-equipped car's ECU calibration (specific ECU OS\strategy....) had adaptive spark control activated in it (the dual spark control that could auto-adjust base spark advance timing based off sensed fuel octane AKI thru knock sensor activity then save it in KAM for future use.....to make it short for some, this is '08-'09 Bullitt & '10 GT only). You'll also note that for 07-09 MY's there were 2 different HP\TQ ratings for the 4.6L V8 based on VIN code....H code is the std 300 HP\320 TQ vers (08-09 Bullitt was H code bumped to 315 HP\325 TQ via specific Ford ECU OS\strategy calibration), S code is the 319 HP\ 330 TQ vers (07-09 Shelby GT\GT-C\GT-H only.....via specific Shelby American 3rd party ECU\strategy calibration).

In short, the typical knock sensor strategies within all 05-10 SO ECUs are more nuanced in operation & have more capabilities\potential than what is largely, publicly understood. To get more on this go here: Lunati VooDoo #21270700 Camshafts | S197 Mustang Forum - S197Forum.com. Start reading from pg 10 onward (covers all from when I started doing my own tuning......including the knock sensors.....that is, if you're interested).

All SO ECU knock sensor strategies work at a base level, once activated, to essentially retard spark advance timing when cyl knock is detected until the knock stops or heaven forbid it caps out during retard (to protect engine from detonation), then will try to always add the cut spark advance timing back once no more cyl knock is detected until either 1.) it caps out during advance or reaches the MBT spark advance tables output w\o exceeding it, whichever comes 1st, depending on how this is all set up in tune file or 2.) detects cyl knock again thus repeating this process. The SO ECU OS\strategy calibration does need to know the fuel's AKI (or octane rating) to be able to "accurately" decipher the assigned cyl KS mic signal post background noise threshold levels for presence of cyl knock.....thus needs to be set in the strategy's VID block to match the fuel's AKI rating being used........

Note: If anyone has used a SCT X4 tuner & looked under "Options" listing when connected to ECU thru OBDII port, the 1st or 2nd item you see listed is the fuel octane selection (87, 89, 91, 93)....this is set in the strategy calibration's VID block to tell the ECU the fuel AKI rating being used.......typical OEM setting is 87 unless this is physically changed then written into ECU......FYI.

IMHO, Ford chose to not use these strategies to their fullest potential but instead chose to set it all up for "safety & reliability purposes"......for public consumption\warranty concerns & marketing strategies to enhance sales.........performance not being the main focus.

Now w\ any 3rd parties involved (like Shelby & Roush), this tuning may be different than what Ford chose to use so you'd need to get w\ the 3rd party to find out where\how all this is set\setup.......unless the means to check this directly for yourselves is available to you.

As for all Coyote Copperhead & up ECU's, this capability is enabled by default......called OAR or Octane Adjust Ratio.......a big leap in capability vs the SO ECU's.

Enough for now..........

As for the OP, I also think either a bad batch of fuel is most likely culprit........or theoretically spark advance getting momentarily cut causing the engine to work harder (using more air\fuel to do the same work thus putting out more heat than it otherwise would have if spark advance timing was normal at the same desired engine load)......which could be the result of a bad batch of fuel.....or just AAT causing the IAT\ECT to exceed a threshold depending on the load\RPM at the specific time of use thus causing the ECT to respond more than usual.

Only way to know for sure is to have had a datalog running to record all then check it to find the actual culprit(s). So, the old adage goes........"if it ain't broke, don't fix it".

Hope this helps.

My 2 cents........................

 

[yote0]

Will the regular overtime do damage to the engine

No, but you are not getting the full 412 hp/390 ft/lbs that you would if running 91 octane. I run my 14 GT on a 93 octane tune except when that gets cost prohibitive. Then I switch to an 87 octane tune. The torque difference is very noticable.

 

[JC SSP]

All my cars run on premium since most are tuned for premium fuel, but even those that are not tuned get 93. For me it's easier to use 93 every time and know I have heard all about octane ratings before, but there is a method to my madness... I stockpiled gasoline in the garage for my generators (Remember I live in S. FL). After a few months, I put in the 93 from the gas cans into the cars and re-fuel on fresh gas for the upcoming storm season.

FYI Lawn mower and other IC engines are all part of that fuel dump... so everything gets 93.

This is the way...