Norwichdelta06

Octane level has nothing to do with amount of cleaning agents in the gas. They basically have the same. Octane level is basically how the vehicle burns/compresses the gas. The 91 is recommended but with technology today and emissions standards you can put 87 in your 91 "RECOMMENDED" and it will not do any harm to your engine or any other part. Because like the other guy said the engine retards itself or adjust timing accordingly to the gas it intakes within milliseconds of getting the crappy gas due to how it ignites "knock sensor"

LILBENZ230

Your car will not suddenly disintegrate if you use 87.. unlike some of the people who responded here seem to believe.

Glyn M Ruck

Guys - this thread is getting a little silly with much misinformation.

Octane rating of a fuel is a measure of it's resistance to knock, pinging, preignition, detonation - by whatever name you know it. It has nothing to do with energy value of the fuel - potential power output etc.

Yes - if you run lower octane fuel than MB recommend the knock sensor will detect this & retard the timing within reason. You do not want this to happen because with retarded timing you increase fuel consumption & reduce power output and efficient running of the engine. As deposit's build up in an engine so it's octane requirement increases over blueprint.

If you want your inlet system to look like this with resultant loss of performance then use cheap non additised gas.



If you want your valves to look like Ichibans with no loss of performance then use Techron or similar additised fuel from a reputable major.

Norwichdelta06

that has nothing to do with the type of octane you use. That's from using cheap gas with no cleaning agents in them. There is the same additives in regular as in premium only difference is compression combustibility etc

Glyn M Ruck

Can you read? No one is suggesting that additised gas relates to Octane?? I was answering two questions.

lberning

If you decide to change wheels, would you be interested in selling them to me?

Yasmin212

I wouldn't recommend it. Im changing my knock sensor now on my C230 and its not something im excited about. The mechanic said it is about a 4 hour job (i think hes over reacting) and it is going to run about 200-300 dollars if im lucky... I dont know if this mechanic is trying to take me for a ride or what not.

LILBENZ230

Wait.. does knock sensor failure have anything at all to do with octane ratings used? I thought the knock sensor was basically a microphone and always active.

Norwichdelta06

it is a sensor that's always in use 100 percent of the time.

acr2001

Nope. You can run bleach through your engine, it's not going to harm the knock sensor. You can kiss the engine goodbye though
It is basically a microphone and it is always active. It's not exposed to any fluids - fuel or otherwise.

LILBENZ230

That's what I thought. So the person who "doesn't recommend" regular gas because he is having to replace his knock sensor doesn't understand the two are not related.

Norwichdelta06

kinda makes me have that same feeling back in the day when i went from dino oil to synthetic and some guy told me once i go synthetic i can't go back or my engine would explode

LILBENZ230

My favorite are the people who act as if engine destruction is immediate upon using 87 octane.

AdidasC230

I have always been told that a turbo car needs premium fuel in a more vital manner as well (prob because of higher comp usually and forced air ect makes it easier to detonate). I had an S40 T5 and it did some odd stuff when you put in crap gas and the knock sensor got wind of it ( I did once, stuck in the BFE mountains in NC). It cut the power down, a noticeable amount, the gas cap light goes on (as if you left it open) and the car wont let you go past 5k rpms. People who put 87 in where told much like here, If you cant afford the gas you shouldn't have the volvo, and the 3 dollars saving per gallon price dif between a fill up of 87 and 93 is a really sad excuse and bad way to save money.

Also some one said, if you not listening to the instructions on the gas cap about the fuel, then why listen to the other labels about seat-belts, oil changes and other maint? I mean you already know more then the maker of the car who garners no profit from you keeping your car in good running order...thought that was funny.

LILBENZ230

Right - but sometimes the premium fuel is recommended because that's the only grade of gasoline that allowed the manufacturers state the HP claims.. and sometimes it is merely a "this is a premium brand car" thing. The 1998 Acura 3.0CL and 1998 Honda Accord V6 both had the same exact J30A1 3.0L VTEC V6. The Accord asked for regular. The Acura's gauges said "Premium Fuel Required". In that case there wasn't even a power discrepancy.

Use of 87 octane is fine and most likely won't hurt your car, but it really won't save you any money - so why do it?

Yasmin212

Actually "the guy" thats recommending not using lower octane gasoline MIGHT know what he is talking about. Im not saying im some master mechanic or what not. I read up on this stuff. I provided some links to show you on the body and copy and pasted the key part of the website if you are to lazy to read it. If you need more sources let me know i have a bunch of other sites.


"By simply performing its function, the knock sensor does two things for your vehicle's engine: (1) it allows optimum engine performance and (2) it protects the engine from potential damages caused by detonation. And because nearly all stock knock sensors used on vehicles today are dependable, you may not find a need to replace them for the life of your vehicle. Acts of carelessness, however, may cause the knock sensor to get damaged. Running the vehicle using fuel with much higher volatility or much lower octane ratings than what is recommended by the vehicle manufacturer are among those things that may cause knock sensor failure. "


http://www.partstrain.com/ShopByDepartment/Knock_Sensor

acr2001

This is ABSOLUTELY WRONG. You are copying text from a MERCHANT website. It's a bunch of crap they wrote to try and get search engine hits / sales.

The knock sensor is a PASSIVE sensor. It is NOT damaged by the type of fuel you use. The knock sensor is just an ear listening to the engine from outside. It's not going to 'wear out' from excessive knock.

When you are at a loud construction site you have to wear ear protection, yes?
Do you also have to protect the microphone on your cell phone from damage? No.

Yasmin212

Okay whatever makes you sleep at night..Interesting how the technican at Silverstar Mercedes stated that this is indeed possible. Your comparing apples to oranges. Construction site noise to a car? and NO a knock sensor is technically not a microphone. the lower the octane rating of the fuel, the more unstable the fuel is under pressure, which means the fuel would ignite before the spark ignites it, causing the timing to be off and the Check Engine lite to come on and in some cases resulting in a knock sensor failure. If you want to add low octane fuel in your car you go right ahead im nobody to stop you. I just tried to be helpful thats what the forum is technically for. Exchanging information and trying to help people get a problem solved.

acr2001

Wow you really have no technical understanding whatsoever.

I have argued in the past that I would never use anything but premium fuel in this car because lower octane fuel isn't a great idea - just for the mileage loss alone it isn't worth using. Thank you for letting me know how knock works I certainly understand that better than you do, and it is not the topic that I brought into question.

Dealerships and their employees make things up constantly in order to easily explain things to gullible customers. If you stick around on this forum and read for a while you will realize that. The knock sensor uses similar technology to a microphone and functions in a very similar way. Obviously you couldn't sing into the damn thing. Please stop pushing this inaccurate info. You are only making it harder for others who want to learn the correct information. My construction site noise comparison does indeed make sense.

Can you even explain *how* it is that you've come to believe low octane fuel will cause harm to the knock sensor? You've already explained how it could cause the engine to knock, but that is not the argument. It seems to me that you think the additional knocking from the engine will somehow wear the knock sensor out. This is not the way it works. It isn't like a shock absorber or a brake pad.

Yasmin212

Acr im done arqueing with you over this issue. It is obvious you engineered the very first mercedes. Im just stating my point and you obviously have yours. Im not saying the moment you pour in regular gasoline its going to burst into flames. If im misinformed I apologize but ill stick to believing my little theory. Ill sleep better tonight.. The point i was trying to make is that low octane fuel throws off the knock sensor and causes the code P0327 to come up. Im not stupid i know the knock sensor has no contact with any form of liquid and its very rare for them to fail. Try it once put in 87 fuel and drive the car till you empty the gas tank then plug in ur OBD reader see what the car says.. Thank you im done now.. it was nice debating with you

acr2001

I have driven my car with a tank of 87. I have also driven our E class with a tank of 87. Driving with 87 octane fuel should not throw an error code in one of these cars unless something else is wrong. I still AGREE with you that it is a BAD idea.

If you have a lot of carbon in your engine just like the photos Glyn posted, then it will result in additional knock with low octane fuel. This would set off a code from the knock sensor. This means that the knock sensor is properly reporting the problem and that you should not be using 87 octane fuel. This DOES NOT harm the knock sensor itself. That's all I have said.

Summary:

Low octane fuel in our cars = stupid idea.
Damage to knock sensor due to low octane fuel = stupid idea (wont happen).
Dealerships lie through their teeth to get $ and then get you to go away.

I'm done now too

LILBENZ230

Sigh.. I've ran like 8 tanks of 87 recently. You know what an OBDII reader in my C230 says?

NO FAULT CODES STORED.

Stop being a moron. It's a piezo sensor, failure is rare, and a tank of 87 is not going to make a knock sensor fail. The G37 had a 3.7L V6 with a compression ratio of 11:1 (or 11.1?) and during a fuel shortage here it could only run on 87. Was it making the same 330hp? No, but I couldn't tell much of a difference in power or fuel economy and it sure as hell didn't affect the sensor.

I'm glad you're finished furthering misinformation and throwing immature tantrums.

Yasmin212

Moron, Throwing immature tantrums? okay lilbenz im arqueing my point and you consider that throwing a tantrum? Your something special i swear. If i said the things i wanted to i would most likely be banned so ill let you say what you need to and this way you might disappear.. later moron.

Yasmin212

And one more thing Acr i bought my car brand new and never did i put in Low octane 87 in my gas tank since i bought the car and one time i went to New Jersey and forgot to tell the gas station attendant what type of fuel i wanted. He assumed i required 87 and put it in. The reason im saying it might throw off the knock sensor is because my mechanic always plugged in the OBD reader every visit. Every time No codes stored came up. My next visit after the gas station situation code P0327 i dont know if this is a single situation or just a coincidence but thats the main reason i looked further into the situation and decided to post on here.

If i misinformed any one of you I apologize I just wanted to help any one of you avoid the similar problem i had.

acr2001

I understand how that coincidence might have caused you to associate the problems. Something must have been going wrong with your engine or your knock sensor. When you put the 87 octane fuel in, it finally pushed things far enough out of tolerance that the error code was thrown.

The reason you seem to be pissing everyone off is because you came in here with 39 posts and little knowledge, yet you refuse to give other members (who have a pretty decent track record of knowing these sorts of things) any credit whatsoever. LILBENZ also knows what he's talking about and I'm sure he doesn't appreciate it when he tries to offer you assistance and then gets **** on.