simonjiang

i let my gf borrow my car for a day, there was about 1/4 tank left and my gf put mid grade fuel into my car not knowing. i'm kinda mad. will this hurt my car?

BCH TL 2013

Your car will be fine.

KidChenz89

iTrader: (1)

if you're scared then throw in fuel injector cleaner next time you fill your tank...but its fine your not the only one lol been there

I hate cars

One tank won't hurt, just don't make a habit of it. No need to do anything special. Sometimes it will take a while for the ecu to put full timing back in so it might take a day for full power and mpg to return once you return to premium

Bearcat94

Problem Containment complete.



Corrective Actions:

Train GF better. If un-trainable, find new GF.

surlynkid

iTrader: (1)

you can run 87 all day long as long as you own the car. the ECU will just retard the timing to prevent pre-detonation. you just end up with less HP.

I hate cars

And I thought for the first time in azine history we would have a decent midgrade fuel thread.

You can't run 87 all the time, the knock sensor is reactive, not proactive. The knock has to happen before the sensor reacts. It can't eliminate detonation on 87, it doesn't have that kind of range, it can only reduce it. By retarding the timing you lose both hp and mpg. You lose mpg to the point that it's more expensive to run 87 octane. You gain nothing by running 87 but you lose hp and mpg. Once you have pinging you have to pull more timing to control it than if you never had any at all. Over the life of the engine you're hammering the rings, pistons, headgaskets, and rod bearings. It a cumulative effect and will eventually hurt the engine given enough time.

There is no such thing as pre-detonation. You have pre-ignition or detonation. Pre-ignition can cause detonation but they are two different things. Pre-ignition is the air fuel mixture igniting before the spark plug fires. Detonation is the uncontrolled explosion of the air fuel mixture instead of the fast burn that supposed to happen.

The knock sensor is there for cases like the OP where the occasional tank of low grade mistakenly gets put in there. It reduces and pretty much eliminates the chance of a quick failure by retarding the timing but it's still hard on the engine. Retarding the timing brings exhaust gas temps way up. Hard on the exhaust valves and hard on the catalytic converters.

fraiolim07

Keep in mind that mid-grade in Mass is still the same octane as the premium out west. Kind of annoyed that I can't find 93 octane anywhere

I hate cars

I've wished so many times that we could get 93. On 91 on a hot summer day, I can't hear the pinging but on the scanner it shows a bit of knock retard, mostly during easy driving. Ironically, once it hits vtec the knock retard goes down a bit.

Bruce Banner

iTrader: (2)

It'd funny, I just had this conversation about 93 octane yesterday.

I never realized it, but yeah, out here in MI, I get 93 octane.
lol

fraiolim07

I wish you hadn't said that . I've never heard it ping so I had assumed that the 91 hasn't really been an issue.

So what do you do to bring the octane up a bit? I read a thread a couple weeks ago that was debating about how many points a bottle of octane booster actually raises a full tank (might have actually been you talking about it, I don't remember), but from what I gathered it was going to be a real pain considering that the octane booster actually does very little, meaning that you would have to add a lot every tank to make any difference. Please correct me if I'm wrong.

Ken1997TL

Remember you're higher in elevation, you don't want the octane to be too high.

YeuEmMaiMai

we get 91 or 92 here, the only time I have filled up with midgrade was when there was no premium available. Never had issues when I was on 89 MPG was down about 2 mpg for that tank, not recommended to use anything other than 91 minimum...

I hate cars

Why is that?

I hate cars

Unfortunately there's not a whole lot you can do cost effectively. Use xylene or toluene to bring the octane up a few points but it's not cheap but MUCH more cost effective than octane booster in a bottle. Buy some 109 octane unleaded and mix but very inconvenient and expensive. Mine only does it when it's 100+ outside so it's not something that most people will have to worry about. I just live with it now. It only shows a few degrees of retard on those really hot days. It's not good but it's not *that* bad on the engine and it's usually for just a couple months out of the year.

gatrhumpy

iTrader: (1)

You should be fine.

And listen to IHC - he knows what he's talking about.

fraiolim07

Yeah, I've noticed that from doing a little bit of reading (working my way through all the pages of the turbo thread ).