Switched Fuel from Shell to Costco and Noticed Something Strange

[46addict]

We are in the hottest part of the year, so some rise in coolant temp is to be expected. Instead of relying on the factory gauge though, you should at least hook up an OBD reader to see where the coolant temp actually is. A side note on the temp readings on these cars, it's an inferred data from the cylinder head temp sensor, and not an in-line sensor in the coolant tract. But regardless, referring to OBD data is more reliable than looking at the factory gauge position.

If it's climbing above 220 or so while waiting at stop lights and the high speed fan cannot keep up, consider changing the antifreeze mix to 40/60 or even 30/70 with 1.5 bottles of Redline water wetter.

You mentioned no knocking so I doubt this is a fuel issue. And increasing will not help.

 

[Olerodder]

Have you been using an injection cleaner every 2/5 tank fulls?
My 14 had a canned tune that came with the SCT/Airaid package I got from Summit. I wanted to do some fine tuning, so contacted Shawn at AED in Sacramento. I have always been a Chevron Premium user in all of my Mustangs, and after datalogging a pull from 30mph in 3rd to redline a number of times I sent it to AED. Shawn called me back and said the datalog showed that I was getting knock from the sensors. This was strange to me, because the engine ran fine, and I could not detect any missfire. I was living in Northern California at the time, and he told me to go to Costco and run two tanks of their premium...I did, then repeated the same datalog test on the same road and at the same temperature during the same time of the morning...no knock was observed by AED in the datalogging...that was the last time I used anything else but Costco Premium, even used it exclusively in my 19GT PP1/A10, which bone stock ran 11.93@117mph in the quarter. I swear buy it, and have for over 8 years.
Yes, most brand stations are Top Tier, but not every brand station puts the same additives in their tanks...also, you can buy no Ethanol gas in California, it's just %30 more expensive when you can find it.

 

[Whpony96]

OK, So did you switch back to Shell and run 2 tanks of Shell through it and the temp go back down? If so then the next phase would be go back to Costco and run 2 tank of their fuel that caused the temp to rise and did it do back up? That's the TRUE way to confirm 100% it is a fuel related issue.

 

[Miker]

What I did was ad 11 gallons of Costco premium to the gas in the tank. I have not seen the needle move since. Costco premium is about the same price as the Shell regular so that is what I am going to run from now on. Since I couldn't find out if the previous owner ever added a tune but it was stated that they ran premium in it I am going to run it just to be safe.
Is there much to be gained from adding a tune to these cars? What is the preferred place to get the device? If it had the ability to show other parameters that would be cool.

 

[Miker]

Have you been using an injection cleaner every 2/5 tank fulls?
My 14 had a canned tune that came with the SCT/Airaid package I got from Summit. I wanted to do some fine tuning, so contacted Shawn at AED in Sacramento. I have always been a Chevron Premium user in all of my Mustangs, and after datalogging a pull from 30mph in 3rd to redline a number of times I sent it to AED. Shawn called me back and said the datalog showed that I was getting knock from the sensors. This was strange to me, because the engine ran fine, and I could not detect any missfire. I was living in Northern California at the time, and he told me to go to Costco and run two tanks of their premium...I did, then repeated the same datalog test on the same road and at the same temperature during the same time of the morning...no knock was observed by AED in the datalogging...that was the last time I used anything else but Costco Premium, even used it exclusively in my 19GT PP1/A10, which bone stock ran 11.93@117mph in the quarter. I swear buy it, and have for over 8 years.
Yes, most brand stations are Top Tier, but not every brand station puts the same additives in their tanks...also, you can buy no Ethanol gas in California, it's just %30 more expensive when you can find it.

Funny you mentioned the injection cleaner. I had just run a few bottles through it on the previous tank.

 

[Miker]

1 last thing I notice about the car. When it has not warmed up yet the throttle response in the lower rpm range seems very responsive. Once the car has warmed up it seems a little sluggish in the same RPM range. Almost as if the car being enriched when cold is the amount of fuel it needs when it is warmed up to. That is why I ran the injector cleaner through it.

 

[Jim O]

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.

Nothing negative will happen by running premium in a car that calls for 87. Its just that it won't make any improvement. Won't hurt anything but your wallet. How long have you had this car ( sorry if I missed that in an earlier post)

 

[Miker]

Got it in November of last year.

 

[MrBhp]

It WILL pull timing with 87. It "probably" will not pull timing with 93.