Oops! 87 octane in my ‘03 3.4L s/c triggered CEL

Anyone had this same issue? I accidentally filled with 87 instead of 91 and noticed some fuel detonation right away. I drove gingerly to my destination about 250 miles away and was able to avoid the pinging after knowing it was there. My check engine has now come on which I suspect may be related to knock sensors? Tonight I just filled up a full tank of 91 and any semblance of dentonation is gone, even at wide open throttle at the top of the revs.

long story short, I’m wondering if anyone can verify/nullify my suspicions, or have any other thoughts? Thanks in advance!

ps. Gonna run a scanner on it tomorrow to check what the code is for the CEL. I will update after I find out.

 

1-don’t do any hard acceleration
2-add some octane boost
3-every time you use 2gals, stop for correct octane for 2gals(flush 87 outta there)

 

The best way to tell is with a code. But if that is ever the case again where you have a full tank of lower octane just add octane boost.

 

What code(s) should I suspect if it was just bad fuel? And anything I should have inspected before driving regularly?

 

Didn't the supercharged 3.4 liters require 91 octane minimum?

Highly unlikely 1 tank of 87 would permanently damage it. At 250 miles you've got to be almost
empty. Fill it with fresh 91 and don't worry.

 

Time to part it out

 

Sounds like you got the 'issue' sorted - I'd recommend tossing a couple bottles of octane boost to keep in the truck in case this happens again in the future, or if you ever go to a gas station that doesn't have 91 available

 

I just bought the truck and seller didn’t specify. So that’s part of the predicament. It has fresh knock sensors too so maybe why CEL came on from one tank

 

Yeah, makes sense that it would come on with only one tank, that setup is optimized to run on premium fuel only. As others have mentioned, a new full tank of premium should sort it. I'd toss a scanner on it and reset the CEL, or disconnect the battery and see if it comes back on.

Congrats on the new ride!

 

UPDATE: after running a scan, it came back with a code P0031 for o2 sensor (bank1, sensor). I cleared the code and will wait for anything to come up again. But seems it was just the wrong fuel and nothing major.

 

On the topic of octane boosters, most of the little bottles you see for sale at gas stations like the STP boosters hardly raise the octane level at all on a full tank of gas. Might go from 87 octane to 87.5. Make sure you check out the label first before relying on them. There are some legit ones like BOOSTane but you'd have to go to a parts store or order online.

 

Lucas is also pretty well rated.

 

VPRacing octanium is my vote

 

Or just look thoroughly to ensure you pressed the correct grade

My question is, you stated you accidentally pump 87, why didn’t you stop. You still pumped a full tank…

 

Accidentally as in I had just bought the truck and did not know until the tank was full. and the seller did not tell me it requires 91. I live in a remote region so the 250 miles I drove there was nothing open cuz it was Easter and all the small towns were closed up. Hence why I didn’t add octane booster immediately

 

Anyone old enough to remember this stuff for the weekends with your parents car?

 

Bummer! Did it ping on you really bad with the 87? And you are not alone. I was asked to look over a BB 427 engine a Cheve dealer had installed in a friend's custom offshore dive boat. When the first head came off, the high-dome pistons were a dead giveaway. The Cheve dealer had installed a real-deal 12.5:1 CR L-88 427 engine in my buddy's boat without informing him that it required uber-octane, non-pump gas. My buddy had already made a couple trips far offshore running pump-gas, so permanent damage was done. The rod and main bearings/high dome pistons/rings/valves were already "pinged" to death from detonation. IIRC, 108 octane was the minimum for the L-88 engine. Our 40 cents a gallon American/Amoco "white" pump gas from the '60s/early '70s was 104. I routinely ran that in my 11:1 CR '66 Mustang GT as we had no Sunoco 260 in our area. Hope no permanent damage was done to your S/C 3.4L.

 

No damage, just an O2 sensor code. I’ll update with more info as it comes in

 

Only one tank and I knew I goofed right away so I just drove slow and easy. It was a not so fun first drive

 

The P0031 code is unrelated to the 87 octane fuel you put in.