Bad gas/wrong octane - wow

[OVERKILL]

So, in anticipation of going to the cottage last weekend, I deviated from going to Costco and went to a lower volume Esso station that was on the way and bought 91. I don't know what happened, I'd almost suspect that I got regular, but I'm honestly not sure. What I do know is that once you got onto the go pedal with any sort of enthusiasm, the pinging just before it shifted was unsettling to say the least. It was LOUD.

Driving around normally, it was fine. You had to be on it a bit to get the very pronounced rattle sound, which I avoided.

I got it down to about 1/2 a tank driving with far less enthusiasm than I normally would and re-filled it with 94 (I normally run 91) the other day and decided to get into it again today, as it has been a few days, and the noise is gone with the 94 in there, so if it was 87 sold as 91, well, I'm somewhere around 91 now.

I know previously we've had some discussions about running 87 in engines that call for 91. Based on this experience, I am going to assume that the FCA/Stellantis 6.4L is NOT tolerant of lower octane fuel under load, it gets VERY upset and pings scarily loud.

 

[walterjay]

Yeah. You got something other than 91 on that fill. Cars can be selective. My Tucson 1.6 turbo says you can run 87 but it runs terrible on it. 89 always and runs the way it should.

 

[The Critic]

I know previously we've had some discussions about running 87 in engines that call for 91. Based on this experience, I am going to assume that the FCA/Stellantis 6.4L is NOT tolerant of lower octane fuel under load, it gets VERY upset and pings scarily loud.

But that is not possible. Modern engines are supposed to have knock sensors that retard timing to prevent this, so your post must be fake news.

Between this post and the one about new oil making the MDS transition feel seamless, are you feeling okay?

 

[wemay]

Glad it worked its way out.

 

[RhondaHonda]

Glad a bit of fuel cleared it up for you. My truck is very noticeably down on power on 87 compared to 93 that I normally run. No pinging but retards timing. I’m cheap and would prefer to run 87 but I like the power levels too much at 93.

 

[Deleted member 89374]

I don't think that you only got lower octane gasoline in there, but probably other crud as well, including possibly some water. A few years back the Sheetz gas stations around whete I live used to be notorious for selling gasoline with high water content in it.

 

[measureman]

I don't think that you only got lower octane gasoline in there, but probably other crud as well, including possibly some water. A few years back the Sheetz gas stations around where I live used to be notorious for selling gasoline with high water content in it.

What did you expect from a gas station named Sheetz?

 

[JeffKeryk]

Wow, I was under the impression the computer would pull timing out before any audible ping.

 

[benjy]

automobile computers can only adjust so much!!! like medical testing theres acceptable + then theirs optimal!! years ago girlfriends new subaru legacy rattled on ALL grades even 93 we have in PA, she quickly traded it. i assume a poor tune + only a 4 spd auto was the issue, the stealer could not find an issue of course!!

 

[blupupher]

Wow, I was under the impression the computer would pull timing out before any audible ping.

It is supposed to, but sometimes takes a few miles to adjust.

 

[Skippy722]

Wow, I was under the impression the computer would pull timing out before any audible ping.

Timing can only do so much, the 6.4L SRT HEMI runs a higher compression ratio (10.9:1) than say the 5.7 HEMI (10.5:1) which is 87 minimum/89 recommended.

 

[walterjay]

He may want to run a can of fuel system cleaner through the next tank

 

[gregk24]

This is one reason why I have always filled up at our local Shell station. The only time I do not is when we are out of town, and in that case I still search for Shell. If one is not available I will use a high volume Top Tier station.

 

[OVERKILL]

Wow, I was under the impression the computer would pull timing out before any audible ping.

I'm sure it does, but it expects 91 and the base timing map is based on 91, so I suspect it is allowed to rattle pretty good before it starts to pull and the sound, well, that's unsettling at the least.

Also, there's a limit as to how much timing you can pull to eliminate ping with 10.9:1 compression, ultimately, the big bores and high compression mean it's going to be unhappy being fed less than what's spec'd.

 

[dishdude]

I don't think that you only got lower octane gasoline in there, but probably other crud as well, including possibly some water. A few years back the Sheetz gas stations around whete I live used to be notorious for selling gasoline with high water content in it.

Ha! When I was a kid they opened a Sheetz near the house and were selling gas for $0.89 or something ridiculous. The old man was thrilled filling up his old Plymouth Acclaim with such cheap gas. The car never ran so bad as it did on that tank of gas! Who knew what was in the gas to make a 2.5 TBI car run so bad.

 

[Skippy722]

I'm sure it does, but it expects 91 and the base timing map is based on 91, so I suspect it is allowed to rattle pretty good before it starts to pull and the sound, well, that's unsettling at the least.

Also, there's a limit as to how much timing you can pull to eliminate ping with 10.9:1 compression, ultimately, the big bores and high compression mean it's going to be unhappy being fed less than what's spec'd.

Plus the kind of fragile pistons the 6.4’s are known for

 

[michaelluscher]

Wow, I was under the impression the computer would pull timing out before any audible ping.

You've clearly never driven an MZ V6 Toyota (my Camry)
I'm back on the 93 now that prices are on the way down, and it still pings slightly under certain conditions
But on 87 it sounds like angry marbles pulling away from every red light
And I could feel where it was down on power, and pulling timing
10.8:1 compression, what're ya gonna do
Also literally no one else but me puts 93 in their MZ V6, like the owners manual recommends you do

 

[Kurtatron]

What did you expect from a gas station named Sheetz?

Reminds me of the power sports dealer in Ohio called Scheit’s PowerSports. How do you say that without cracking up?

 

[CarLuver]

my buddy has a 88 f150 350 V8. when he puts arco in it , it pings very easily. we were trying to figure out what to do like retard the timing or something like that. then i suggested he go to costco and fill it up with a tank of regular. the ping disappeared . now he gets his gas at costco.

 

[doublebase]

I’ve run into similar situations with bad gas: a computer is only going to be to do so much in regards to pulling timing and preventing knock, and when you have a big V8 it’s noticeable. That’s a lot of cylinders being effected at once. Now a single misfire in a V8? Sometimes they’re not so bad because all those other cylinders can really compensate, but when you’re talking bad fuel, 8 cylinders are going to magnify the problem. IMO.